Dissertations / Theses on the topic 'Functionalized carbon'
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1
Vurur, O. F., and I. E. Serhatli. "Functionalized Multiwalled Carbon Nanotubes for UV Coating." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35294.
Full textAbstract:
We propose a strategy to enhance the photocurable properties of the multi walled carbon nanotube (Mwcnt) / binder films through control of the intermolecular interaction between the nanotube and the binder material. For this aim, photosensitive functionalized carbon nanotube was synthesized and by mixing binder, it was cured under UV-light. Epoxy acrylate resin was used as binder and reactive diluents such as HDDA, DPGDA were added as both crosslinker and viscosity extender.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35294
2
Rauf, Hendrik. "Metallic Ground State of Functionalized Carbon Nanotubes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1184153423397-79783.
Full textAbstract:
Single-wall carbon nanotubes (SWCNTs) are a fascinating material because they exhibit many outstanding properties. Due to their unique geometric structure, they are a paradigm for one-dimensional systems. Furthermore, depending on their chirality, they can be either metallic or semiconducting. The SWCNT are arranged in bundles of some ten nanotubes with a random distribution of semiconducting and metallic tubes. They are thus one-dimensional objects embedded in a three-dimensional arrangement, the bundles. In this thesis, the metallic ground state of one-dimensional (1D) and three-dimensional (3D) systems is investigated on the basis of SWCNTs, using angle-integrated photoemission spectroscopy. In particular, a transition from a 1D to a 3D metallic system, induced by a charge transfer, is studied on SWCNTs and C60 peapods. In general, the metallic ground state of materials is greatly influenced by correlation effects. In classical three-dimensional metals, electron-electron interaction mainly leads to a renormalization of the charge carrier properties (e.g. effective mass), as described in Landau's Fermi liquid theory. One-dimensional metals are influenced to a greater extent by interactions. In fact, the Landau-quasiparticle picture breaks down due to the Peierls instability. Instead, one-dimensional metals are described by Tomonaga-Luttinger liquid (TLL) theory which predicts unusual properties such as spin-charge separation and non-universal power laws in some physical properties such as the electronic density of states (DOS). Angle-integrated photoemission spectroscopy provides direct access to the DOS and as such directly addresses the power law renormalization of a TLL. It is first shown, that the bundles of single-wall carbon nanotubes indeed exhibit a power law scaling of the electronic density of states is observed as it is expected from TLL theory. The main part of the thesis is devoted to the investigation of the metallic ground state of SWCNTs upon functionalization. In general, functionalization is a controlled modification of the structural and/or electronic properties of SWCNT. It can be carried out e.g. by doping with electron donors or acceptors, by filling the nanospace inside the tubes with molecules or by substituting carbon atoms. First, the behavior of the SWCNT upon chemical doping was probed. The overall modification of the electronic band structure can be explained well by a rigid band shift model. The one-dimensional character of the metallic tubes in the bundle is retained at low doping, but when the semiconducting tubes in the sample are also rendered metallic by the charge transfer, a Fermi edge emerges out of the power law renormalization of the spectral weight, signifying a transition to a three-dimensional metallic behavior. This can be explained by an increased interaction between the tubes in the bundle. A crossover from a Tomonaga-Luttinger liquid to a Fermi liquid is observed. The filling of SWCNTs with C60 molecules leads to the formation of so-called peapods. It raises questions concerning the role of the additional bands originating from the C60 filling in the one-dimensional system. In the pristine state, the states of the C60 filling were found to have no influence on the metallic ground state. The TLL power law scaling of the density of states is observed. The overall interaction between the SWCNT host and the C60 filling is small. Upon doping however, the modified band structure leads to a qualitative change in the crossover from a TLL to a Fermi liquid. Upon doping, also states in the conduction band of the C60 are filled. The evolution of the power law scaling at intermediate doping can be interpreted as an opening of an additional conduction channel of one-dimensional metallic chains of C60 inside the tubes. This is in good agreement with transport experiments. Upon further doping, a Fermi edge similar to the highly doped SWCNTs is observed.
3
Penmatsa, Varun. "Functionalized Carbon Micro/Nanostructures for Biomolecular Detection." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/739.
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Advancements in the micro-and nano-scale fabrication techniques have opened up new avenues for the development of portable, scalable and easier-to-use biosensors. Over the last few years, electrodes made of carbon have been widely used as sensing units in biosensors due to their attractive physiochemical properties. The aim of this research is to investigate different strategies to develop functionalized high surface carbon micro/nano-structures for electrochemical and biosensing devices.
High aspect ratio three-dimensional carbon microarrays were fabricated via carbon microelectromechanical systems (C-MEMS) technique, which is based on pyrolyzing pre-patterned organic photoresist polymers. To further increase the surface area of the carbon microstructures, surface porosity was introduced by two strategies, i.e. (i) using F127 as porogen and (ii) oxygen reactive ion etch (RIE) treatment. Electrochemical characterization showed that porous carbon thin film electrodes prepared by using F127 as porogen had an effective surface area (Aeff 185%) compared to the conventional carbon electrode.
To achieve enhanced electrochemical sensitivity for C-MEMS based functional devices, graphene was conformally coated onto high aspect ratio three-dimensional (3D) carbon micropillar arrays using electrostatic spray deposition (ESD) technique. The amperometric response of graphene/carbon micropillar electrode arrays exhibited higher electrochemical activity, improved charge transfer and a linear response towards H2O2 detection between 250μM to 5.5mM.
Furthermore, carbon structures with dimensions from 50 nano-to micrometer level have been fabricated by pyrolyzing photo-nanoimprint lithography patterned organic resist polymer. Microstructure, elemental composition and resistivity characterization of the carbon nanostructures produced by this process were very similar to conventional photoresist derived carbon. Surface functionalization of the carbon nanostructures was performed using direct amination technique.
Considering the need for requisite functional groups to covalently attach bioreceptors on the carbon surface for biomolecule detection, different oxidation techniques were compared to study the types of carbon–oxygen groups formed on the surface and their percentages with respect to different oxidation pretreatment times.
Finally, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor oncoprotein detection on functionalized three-dimensional carbon microarrays platform was demonstrated. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5 pmol.
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Rauf, Hendrik. "Metallic Ground State of Functionalized Carbon Nanotubes." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A24959.
Full textAbstract:
Single-wall carbon nanotubes (SWCNTs) are a fascinating material because they exhibit many outstanding properties. Due to their unique geometric structure, they are a paradigm for one-dimensional systems. Furthermore, depending on their chirality, they can be either metallic or semiconducting. The SWCNT are arranged in bundles of some ten nanotubes with a random distribution of semiconducting and metallic tubes. They are thus one-dimensional objects embedded in a three-dimensional arrangement, the bundles. In this thesis, the metallic ground state of one-dimensional (1D) and three-dimensional (3D) systems is investigated on the basis of SWCNTs, using angle-integrated photoemission spectroscopy. In particular, a transition from a 1D to a 3D metallic system, induced by a charge transfer, is studied on SWCNTs and C60 peapods. In general, the metallic ground state of materials is greatly influenced by correlation effects. In classical three-dimensional metals, electron-electron interaction mainly leads to a renormalization of the charge carrier properties (e.g. effective mass), as described in Landau's Fermi liquid theory. One-dimensional metals are influenced to a greater extent by interactions. In fact, the Landau-quasiparticle picture breaks down due to the Peierls instability. Instead, one-dimensional metals are described by Tomonaga-Luttinger liquid (TLL) theory which predicts unusual properties such as spin-charge separation and non-universal power laws in some physical properties such as the electronic density of states (DOS). Angle-integrated photoemission spectroscopy provides direct access to the DOS and as such directly addresses the power law renormalization of a TLL. It is first shown, that the bundles of single-wall carbon nanotubes indeed exhibit a power law scaling of the electronic density of states is observed as it is expected from TLL theory. The main part of the thesis is devoted to the investigation of the metallic ground state of SWCNTs upon functionalization. In general, functionalization is a controlled modification of the structural and/or electronic properties of SWCNT. It can be carried out e.g. by doping with electron donors or acceptors, by filling the nanospace inside the tubes with molecules or by substituting carbon atoms. First, the behavior of the SWCNT upon chemical doping was probed. The overall modification of the electronic band structure can be explained well by a rigid band shift model. The one-dimensional character of the metallic tubes in the bundle is retained at low doping, but when the semiconducting tubes in the sample are also rendered metallic by the charge transfer, a Fermi edge emerges out of the power law renormalization of the spectral weight, signifying a transition to a three-dimensional metallic behavior. This can be explained by an increased interaction between the tubes in the bundle. A crossover from a Tomonaga-Luttinger liquid to a Fermi liquid is observed. The filling of SWCNTs with C60 molecules leads to the formation of so-called peapods. It raises questions concerning the role of the additional bands originating from the C60 filling in the one-dimensional system. In the pristine state, the states of the C60 filling were found to have no influence on the metallic ground state. The TLL power law scaling of the density of states is observed. The overall interaction between the SWCNT host and the C60 filling is small. Upon doping however, the modified band structure leads to a qualitative change in the crossover from a TLL to a Fermi liquid. Upon doping, also states in the conduction band of the C60 are filled. The evolution of the power law scaling at intermediate doping can be interpreted as an opening of an additional conduction channel of one-dimensional metallic chains of C60 inside the tubes. This is in good agreement with transport experiments. Upon further doping, a Fermi edge similar to the highly doped SWCNTs is observed.
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Pokhrel, Sewa. "FISCHER- TROPSCH SYNTHESIS ON FUNCTIONALIZED CARBON NANOTUBES." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1408.
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The aim of this research was to investigate the role of chemical functionalization on carbon nanotubes surfaces and its effect on FT catalysis. Multi walled carbon nanotubes (MWNT) were first treated with acid (HCl) to remove the residual metal particles and were then functionalized using H2O2 and HNO3 to introduce oxygen-containing groups to the MWNT surface. These treatments also add defects on MWNT surface. Morphological analyses were performed on the MWNT samples with TEM and it was found that the peroxide and acid treated MWNTs showed an increase oxygen functional groups and created additional surface defects on the MWNTs. Results of FT experiments showed enhanced CO conversion, FT activity and product selectivity towards liquid hydrocarbons due to functionalization. The liquid selectivity was found to be significantly high for H2O2 treated catalyst. HNO3 treated catalyst had highest activity although selectivity to methane and CO2 was found higher than the H2O2 treated catalyst. It was observed that the chemical treatments increase the carbon chain length of the produced hydrocarbons. While comparing hydrocarbon distribution of as-produced and H2O2 treated MWNT, it was found that carbon-chain length increases for peroxide treated catalyst. Along with as-produced and functionalized nanotube, FT experiments were also conducted using B-doped sponge, un-doped sponge and N-doped CNT catalyst. B-doped sponge showed enhanced CO conversion and FT activity as compared to un-doped sponge. Conversion and product selectivity were found to be affected by temperature when test was conducted with N-CNT. Operating conditions like temperature, syngas feed flow rate and syngas ratio were also to impact the FT performance.
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Yang, Lin. "Functionalized double-walled carbon nanotubes for integrated gas sensors." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30254/document.
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Nous proposons dans ce travail une méthode robuste et bas-coût afin de fabriquer des détecteurs de gaz à base de Nanotubes de Carbone bi-parois (DWCNTs) chimiquement fonctionnalisés. Ces nano-objets (DWCNTs) sont synthétisés par dépôt catalytique en phase vapeur (CCVD), puis purifiés avant d'être oxydés ou bien fonctionnalisés par des terminaisons fluorées ou aminées. Les dispositifs de détection électriques ont été fabriqués par lithographie douce en utilisant un pochoir de PDMS (Poly-DiMethyl Siloxane) et un dépôt en phase liquide à la pipette d'une suspension aqueuse contenant les nanotubes fonctionnalisés, rinçage puis séchage à l'azote sec. Chaque dispositif (1 cm X 2 cm) est équipé d'un jeu de 7 résistors à base de DWCNTs. Chaque résistor peut accueillir des nanotubes fonctionnalisés par une entité chimique différente afin de cibler un gaz spécifique, permettant ainsi une détection multiplexée. En raison de leur faible encombrement et la possibilité de les fabriquer sur tout type de substrat y compris des substrats souples, ces détecteurs pourraient être utilisés pour une large gamme d'applications et notamment les détecteurs de gaz portatifs et intégrés. La résistance électrique des résistors s'avère décroître avec la température suggérant une conduction électrique gouvernée par l'effet tunnel et les fluctuations au sein du tapis désordonné de nanotubes de carbone. Nous avons cependant montré dans ce travail que pour des applications réelles de détection de gaz, une régulation thermique des dispositifs n'est pas nécessaire car les variations de résistance engendrées par l'adsorption de molécules de gaz sont significativement plus grandes que les variations causées par de possibles fluctuations de température. Les dispositifs produits présentent un caractère métallique à température ambiante et pour des applications de détection de gaz nous avons sélectionné des dispositifs présentant des résistances inférieures à 100 kO. Le principe de base de la détection de gaz étant basé sur la mesure directe de la résistance électrique du dispositif, la consommation électrique de ces dispositifs reste faible (<1 µW). La réponse des dispositifs à base de nanotubes de carbone non fonctionnalisés aux analytes testés (éthanol, acétone, ammoniac et vapeur d'eau) est faible. Les nanotubes de carbone fonctionnalisés présentent quant à eux, une réponse modérée à la vapeur d'eau, à l'éthanol et à l'acétone mais montrent une sensibilité excellente à l'ammoniac. En particulier, les nanotubes de carbone oxydés se sont avérés capables de détecter des concentrations sub-ppm d'ammoniac en présence de vapeur d'eau en excès et à température ambiante et ont montré une grande stabilité dans le temps même pour des expositions de gaz répétées. Nous pensons que les groupes chimiques fonctionnels ancrés à la surface des nanotubes de carbone modifient les interactions entre les molécules de gaz et les nanotubes et que le transfert de charges induit provoque les modifications de la conductance électrique du systèmeWe have successfully fabricated gas sensors based on chemically functionalized double-wall carbon nanotubes (DWCNTs) using a robust and low cost process. The DWCNTs were synthesized by catalytic chemical vapor deposition (CCVD) method. They were then purified before functionalization (oxidation, amination, and fluorination). The sensor devices were fabricated by soft lithography using PDMS (Poly-DiMethylSiloxane) stencils and liquid phase pipetting of a suspension of chemically functionalized DWCNTs in deionized water, rinsing and finally drying in a nitrogen flow. Each device (1 cm x 2 cm) is equipped with a set of 7 DWCNT based resistors. Each resistor can accommodate a precise chemical functionalization for targeting a specific gas species, allowing a multiplexed (up to 7) detection. Due to their small size and the possibility to fabricate them on soft substrates, they could be used for many kinds of applications including wearable devices. The electrical resistance of the produced resistors turned out to decrease with temperature, suggesting fluctuations induced tunneling conduction through the disordered network of metallic nanotubes. However, we have shown in our work that for realistic applications, gas sensing can be achieved without any temperature regulation of our devices, because the variations of electrical conductance caused by gas molecules adsorption are significantly larger than those caused by possible temperature fluctuations. The as fabricated devices exhibit at room temperature a metallic conducting behavior. Devices with a resistance less than 100 kO were selected for gas detection. Because the sensing principle is based on the direct measurement of the resistance, our scheme ensures low power consumption (<1 µW). Raw (not functionalized) DWCNTs-based gas sensors exhibited a low sensitivity to the tested analytes, including ethanol, acetone, ammonia and water vapor. Functionalized DWCNTs-based gas sensors exhibited a moderate sensitivity to ethanol, acetone and water vapor but the response to ammonia, even in the presence of additional water vapor, was excellent. In particular, oxidized DWCNTs based gas sensors exhibited a high stability in the case of prolonged and repeated gas exposures. The oxidized DWCNTs gas sensors were also able to detect ammonia vapor at sub-ppm concentration in the presence of water vapor at high concentration
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Park, Hyoungki Lu Jianping. "Electronic and transport properties of functionalized carbon nanotubes." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,356.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics & Astronomy." Discipline: Physics and Astronomy; Department/School: Physics and Astronomy.
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Lim, Chee-Sern. "Fabrication of multifunctional nanocomposites using functionalized carbon nanofibers." Diss., Wichita State University, 2013. http://hdl.handle.net/10057/7026.
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In this work, several novel techniques to fabricate nano-engineered polymeric composites (or nanocomposites) containing functionalized carbon nanofibers (CNFs) were developed. The methodologies address current manufacturing issues of nano-engineered polymeric composites by effectively incorporating functionalized CNFs into polymer matrix and glass fiber layers. For polymeric nanocomposites, optical images of the nanocomposites revealed uniform distribution and alignment of the CNFs in the direction of the electric field. Due to the similarity in the alignment morphology, it was observed that alignment structure of the functionalized CNFs was independent of the functional groups grafted to the CNFs. Test results indicated that mechanical and electrical properties (measured parallel to the direction of the aligned CNFs) of nanocomposites containing aligned CNF network were improved in comparison to nanocomposites containing randomly distributed CNFs and neat epoxy sample. Discussion regarding the contribution of CNF type towards the mechanical and electrical properties is presented. In the first hierarchical composites study, functionalized CNFs were uniformly incorporated into glass fiber layers without inducing significant CNF agglomerate through a simple filtration process. Both in-plane and out-of-plane electrical conductivity of hierarchical composites were comparable to the conductivity of carbon fiber composites due to the formation of conductive path by CNFs. The second study presented the synthesis of functionalized CNF/glass fiber assembly demonstrating that functionalized CNF entangled network can be used to join glass fiber layers in the absence of polymer matrix. Test results showed that the peeling force required to separate the functionalized CNF/glass fiber assembly was significant due to the functionalized CNF entangled network. Possible explanations for both studies are provided in order to investigate the contribution of functionalized CNFs in each form of material.Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Kaufmann, Anika, David Kunhardt, Giuseppe Cirillo, Silke Hampel, and Bernd Schwenzer. "Functionalized carbon nanotubes as transporters for antisense oligodeoxynucleotides." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-156811.
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The use of DNA-based therapeutics requires efficient delivery systems to transport the DNA to their place of action within the cell. To accomplish this, we investigated multiwalled carbon nanotubes (pristine MWCNT, p-MWCNT) functionalized with hydroxyl groups via 1,3-dipolar cycloaddition. In this way, we have obtained MWCNT-f-OH with improved stability in aqueous dispersions which is an advantageous property for their use in cellular environments. Afterwards, a carrier strand oligodeoxynucleotide (CS-ODN) was adsorbed to MWCNT-f-OH followed by hybridization with a therapeutic antisense oligodeoxynucleotide (AS-ODN). The amount of adsorbed CS-ODN, as well as the complementary AS-ODN and a non-complementary oligodeoxynucleotide (NS-ODN) as reference, was directly measured by radionuclide labeling of ODNs. We show that subsequent release of AS-ODNs and NS-ODNs was possible for MWCNT-f-OH above the melting temperature of AS-ODNs at 80 °C and under physiological conditions at different pH values at 37 °C. We also show a very low influence of p-MWCNT and MWCNT-f-OH on the cell viability of the bladder carcinoma (BCa) cell line EJ28 and that both MWCNT types were internalized by EJ28. Therefore, MWCNT-f-OH represents a promising carrier able to transport and release AS-ODNs inside cells.
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Ryu, Janet (Janet Sun). "Work functions of functionalized singled-walled carbon nanotubes." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35056.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (leaves 39-40).
Introduction: Carbon nanotube (CNT) structures were discovered by Sumio Iijima in 1991 at NEC laboratories in Japan. Since their discovery, scientists and engineers have been fascinated by their electrical and mechanical properties. Their unique characteristics, in addition to their nanoscale size, have generated much excitement about the possible applications of this novel. material.
by Janet Ryu.
S.B.
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Pham, Van Dong. "STM characterization of functionalized carbon nanotubes and graphene." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC245.
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Dans cette thèse, nous avons étudié l'interaction entre des molécules organiques et des nanomatériaux de carbone. En utilisant un microscope à effet tunnel (STM) à basse température et sous ultra-vide, nous avons mesuré les propriétés de molécules de porphyrine physisorbées sur du graphène ou des nanotubes de carbone. Nous avons d'abord étudié l'injection d'électrons dans le graphène sur des défauts (joints de grains et atomes d'azote insérés). Une étude d'états image résonants nous a également permis de mettre en évidence une variation locale du travail de sorite dans le graphène dopé. Nous avons ensuite étudié les propriétés de molécules de porphyrine (H2TPP) adsorbées sur une surface Au(111). En utilisant la pointe du microscope nous avons induit des réactions de tautomérisation et de déshydrogénation et montré comment cela modifie les états moléculaires et l'interaction molécule-surface. Nous avons ensuite étudié l'interaction du graphène avec des molécules de porphyrine. Nous avons montré que le couplage électronique est faible entre les molécules et le graphène. Nous avons ensuite montré comment un atome d'azote inséré dans le réseau de carbone du graphène modifie l'interaction molécule-surface. Une diminution de l'énergie des états moléculaires au niveau des sites dopants révèle un transfert de charge partiel entre les sites d'azote et les molécules. Dans la dernière partie, nous avons étudié les propriétés de nanotubes de carbone monoparois fonctionnalisés par un polymère de porphyrine. Les mesures ont révélé que le polymère couvre partiellement les nanotubes. La spectroscopie locale a indiqué que la densité d'états locale est modifiée au niveau du polymèreIn this thesis we studied the interaction between organic molecules and carbon nanomaterials. Using scanning tunneling microscopy (STM) at low temperature and in ultra-high vacuum, we measured the properties of porphyrin molecules at the surface of graphene and single-walled carbon nanotubes. We first studied electron injection in graphene at defect sites (grain boundaries and nitrogen doping atoms). Using image-potential states, we evidenced the variation of local work function in doped graphene. Secondly, we investigated the properties of free-base porphyrin (H2TPP) molecules adsorbed on a Au(111) surface. We performed tip-induced tautomerization and dehydrogenation of the molecules, and revealed how these operations modify the molecular states and molecule-substrate interaction. Following these two preliminary studies, we studied the interaction of graphene with porphyrin molecules. We evidenced a weak electronic coupling between the molecules and graphene. We then showed how a nitrogen dopant on doped graphene can tune the molecule-surface interaction. The comparison between molecules adsorbed on nitrogen doping sites with those adsorbed on carbon sites clearly reveals a downshift of the energy of the molecular states at the doping sites. This downshift reveals a partial electron transfer from the nitrogen sites of graphene to the adsorbed molecules. In the last part of this thesis, we studied the properties of single-walled carbon nanotubes functionalized with a porphyrin polymer. The STM measurements revealed that the polymer is partially covering the nanotubes. Local spectroscopy indicated that the local density of states are modified at the polymer location
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Barman, Poulami. "The interaction of peptides with functionalized carbon nanotubes /." Online version of thesis, 2009. http://hdl.handle.net/1850/8688.
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Krause, Caitlin Joy. "Evaluating the toxicity of nitrogen-functionalized carbon nanotubes." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4667.
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Pacheco, Rodriguez Diana Marisol. "Aminosilane-functionalized cellulosic polymers for increased carbon dioxide sorption." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42722.
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Improvement of the efficiency of carbon dioxide (CO2) separation from flue gases has been identified as a high-priority research area to reduce the total energy cost of carbon capture and sequestration technologies in coal-fired power plants. Efficient CO2 removal from flue gases by adsorption systems requires the design of novel sorbents capable of capturing, concentrating and recovering CO2 on a cost-effective basis. The preparation of a novel aminosilane-functionalized cellulosic polymer sorbent by grafting of aminosilanes showed promising performance for CO2 separation and capture. A strategy for the introduction of N-(2-aminoethyl)-3-aminoisobutyldimethylmethoxysilane functionalities into cellulose acetate backbone by anhydrous grafting is described in this study. The dry sorption capacity of the aminosilane-functionalized cellulosic polymer reached 27 cc (STP) CO2/ cc sorbent at 1 atm and 39 cc (STP) CO2/ cc sorbent at 5 atm and 308 K. Exposure to water vapor slightly increased the sorption capacity of the sorbent, suggesting its potential for rapid cyclic adsorption processes under humid feed conditions. In addition, a strategy for the preparation of a cellulose acetate-titanium(IV)
oxide sorbent by the reaction of cellulose acetate with titanium tetrachloride is presented.
The organic-metal hybrid sorbent presented a sorption capacity of 14 cc (STP) CO2/ cc sorbent at 1 atm and 49 cc (STP) CO2/ cc sorbent at 5 atm and 308 K. The novel CO2 sorbents were characterized in terms of chemical composition, density changes, molecular structure, thermal stability, and surface morphology.
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Sreeramoju, Mahendra K. "PREPARATION, CHARACTERIZATION AND APPLICATIONS OF FUNCTIONALIZED CARBON NANO-ONIONS." UKnowledge, 2013. http://uknowledge.uky.edu/chemistry_etds/20.
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Carbon nano-onions (CNOs) discovered by Ugarte in 1992 are multi-layered fullerenes that are spherical analogs of multi-walled carbon nanotubes with diameters varying from 6 nm to 30 nm. Among the various methods of synthesis, CNOs prepared by graphitization of nanodiamonds (N-CNOs) and underwater electric arc of graphite rods (A-CNOs) are the subject of our research. N-CNOs are considered as more reactive than A-CNOs due to their smaller size, high curvature and surface defects.
This dissertation focuses on structural analysis and surface functionalization of N- CNOs with diameters ranging from 6—10 nm. Synthetic approaches such as oleum- assisted oxidation, Freidel-Crafts acylation and Billups reductive alkylation were used to functionalize N-CNOs to improve their dispersion properties in aqueous and organic solvents. Functionalized N-CNOs were characterized using various techniques such as TGA, TG-MS, Raman spectroscopy and pH-titrimetry. We designed an experimental method to isolate polycyclic aromatic adsorbates formed on the surface of oleum oxidized N-CNOs (ON-CNOs) and characterized them.
A-CNOs, on the other hand are bigger than N-CNOs with diameters ranging from 20—40 nm. In this dissertation, we discuss the preparation of graphene structures by unzipping of A-CNOs using KMnO4 as oxidizing agent. These graphene structures were characterized using powder X-ray diffraction, TGA, BET nitrogen adsorption/desorption studies and compressed powder conductivity.
This dissertation also focuses on lithiation/delithiation studies of N-CNOs, A- CNOs and A-CNO-derived graphene structures to use them as negative electrode materials in lithium-ion batteries. The cycling performances of these materials at a charge/discharge rate of C/10 were discussed. The cycling performance of N-CNOs was tested at faster charge/discharge rate of C.
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Venturelli, Enrica. "Antibody-functionalized carbon nanotubes towards a targeted anticancer therapy." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/VENTURELLI_Enrica_2011_ED222.pdf.
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Récemment les nanotubes de carbone sont apparus comme un matériau unique dans le domaine des nanotechnologies et des nanosciences, en particulier en nanomédecine comme vecteurs pour la délivrance de médicaments. Durant ma thèse, j’ai développé des conjugués à base de nanotubes et d’anticorps pour développer une nouvelle stratégie ciblée de thérapie anti-cancéreuse. Actuellement, les anticorps ne peuvent pas être utilisés contre des cibles intracellulaires à cause de leur faible aptitude à traverser la membrane plasmique. Par contre, il a été montré que les nanotubes ont la capacité de traverser la membrane cellulaire via différents mécanismes (endocytose ou diffusion passive). Dans ce contexte, j’ai utilisé les nanotubes comme vecteurs pour la délivrance de molécules biologiquement actives à l’intérieur des cellules tumorales ciblées par l’anticorps. Nous avons démontré la possibilité de fonctionnaliser soit la paroi, soit les pointes des nanotubes avec deux types d’anticorps : un anticorps de ciblage de cellules tumorales ou un anticorps thérapeutique. Une fois liés aux nanotubes, les anticorps conservent leur activité de reconnaissance de l’antigène. Afin d’utiliser ces conjugués à des fins biomédicales, nous avons évalué leur profils pharmacocinétiques et toxicologiques. Ces études ont montré que les conjugués sont biocompatibles et ont tendance à être répartis dans différents organes (fois, rate et poumons). Les résultats obtenus sont encourageants quant à l’utilisation des nanotubes fonctionnalisés comme nouveau système de vectorisation de molécules biologiquement activesRecently, carbon nanotubes (CNTs) have emerged as new and promising materials for applications in different research fields such as nanotechnology and materials science. Recent studies on the ability of CNTs to form supramolecular complexes with nucleic acids or proteins triggered their applications in the biomedical domain, for example as drug delivery system. In this thesis, I focused my interest on the design and synthesis of antibody-CNT conjugates for targeted cancer therapy. The nanotubes are used as delivery system whereas the antibody is the targeting moiety for cancer cells. Nowadays antibodies represent a promising anticancer therapy, however they have not been utilized against intracellular targets because of their low aptitude to traverse the plasma membrane. On the contrary, CNTs have shown the ability to easily cross cell membrane via two mechanisms (endocytosis or passive diffusion). Results confirmed the possibility to covalently functionalize carbon nanotubes either with a targeting antibody or a therapeutic immunoglobulin. Once bound onto the surface of CNTs (sidewall or tips), surface plasmon resonance results displayed the conservation of the ability of the antibody to recognize the antigen. Important aspects related to the biomedical applications of these constructs are the evaluation of their potential toxicity and biodistribution profiles. Results indicated that the conjugates are biocompatible and they distribute mainly in liver, spleen and lungs. This work shows great promise for the use of functionalized carbon nanotubes as novel delivery system for drugs or bioactive molecules
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Ojo, Kolade Omoniyi. "Mesoporous Functionalized Materials for Post-Combustion Carbon Dioxide Capture." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1378.
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Novel highly functionalized hybrid organic-inorganic materials were synthesized by polycondensation of bis[3-(trimethoxysilyl)propyl]amine in presence of cationic and anionic surfactants. Reaction media strongly affected gelation time. Thus, in basic media gelation occurred immediately while acid increased gelation time. Material structures were studied by IR spectroscopy, porosimetry, XRD, and SAXS methods. In spite of the absence of an inorganic linker, obtained bridged silsesquioxanes had mesoporous structure. A material prepared in the presence of dodecylamine as a template had higher surface area and narrow pore size distribution while the use of sodium dodecylbenzene sulfate resulted in formation of mesopores with wide size ranges. Accessibility of surface amine groups in silsesquioxanes was studied for molecules of acidic nature and different sizes: HCl, CO2 and picric acid. High contents of accessible amine groups in these materials make them prospective adsorbents for post-combustion CO2 capture.
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Liu, Jiayi. "Functionalized Octatetrayne as Novel Carbon Media for Capillary Liquid Chromatography." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428922624.
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Ziem, Benjamin [Verfasser]. "Polyvalent Virus Inhibitors Based on Functionalized Carbon Nanoarchitectures / Benjamin Ziem." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1130656705/34.
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Zhou, Zheng. "The Investigation of Functionalized Carbon Nanotubes for the Carbon Dioxide Capture and Ethane Oxidative Dehyrogenation Catalysts." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8417.
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Carbon nanotubes (CNT) have gained interest for wide use as both support and catalyst due to the ease of uniquely tunable surface chemistry. Increasingly severe greenhouse effects have attracted attention to novel materials and technologies capable of capturing carbon dioxide (CO2). In this context, we develop a CNT based solid state amine for the CO2 capture. CNT are functionalized under various methods as a support for polymeric amines. Polyethyleneimine are physically adsorbed on CNT and are further characterized and studied for reversible CO2 capture. We obtain a high CO2 capture capacity (6.78 mmol∙g-1) for linear polyethyleneimine (LPEI) and 6.18 mmol∙g-1 for branched polyethyleneimine (BPEI). Based on the study of pore structure, we also demonstrate that in a steam post-combustion environment, supported polymeric amines on CNT show higher stability than traditional metal oxides. Besides the increased stability of the support in steam, we also improve the stability of amines under steam conditions by developing a covalent modification method. The CO2 capture capacity of the covalent bonded materials under steam conditions improved by 14% compared to dry conditions. In addition, the loading, chemical properties of PEI, and the surface chemistry of CNT remained stable under steam conditions compared to physically adsorbed PEI on CNT. These results suggest that covalent bonded PEI on CNT can be more suitable for CO2 capture in post-combustion processes. A different CNT application is as a catalyst for oxidative dehydrogenation (ODH) of ethane, and herein we develop a new processing technique for tuning the surface chemistry of the CNT-based catalyst. A one-step, gas-phase hydrogen (H2) surface modification is used to reduce carboxylic groups to phenolic groups on carbon nanotube (CNT) materials. This technique is greener and more facile for large-scale industrial catalysts than what has previously been reported. This method uses fundamental principles of CNT surface chemistry to efficiently reduce the unselective oxidation sites and enhances the active sites used for alkane oxidative dehydrogenation. The resulting catalyst improves the ethylene selectivity and yield by at most 81% and 28% respectively compared to the non-modified catalyst. A clear linear correlation between the functional groups and catalytic activity reveals the effect of specific oxygen species on performance. As the catalyst surface area increases, pretreatments generate more selective active sites instead of over-oxidation sites, providing a guideline for catalyst optimization. We suggest that the gas-phase H2 method is general for reducing carbon catalysts to increase selective oxidation sites for gas phase reactions.
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Chan, Wai-Fong. "Functionalized carbon nanotube thin-film nanocomposite membranes for water desalination applications." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/64372.
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Cost-effective purification and desalination of water is a global challenge. Reverse osmosis (RO), the current method of choice, requires high pressure drops across the membranes in order to achieve acceptably high flow rates. Conventional polymer membranes are limited in their performance by a trade-off between water permeability and water/salt selectivity. Biofilm fouling is another critical problem in RO applications. Recent simulations and experiments suggest that properly functionalized carbon nanotubes (CNTs) can be used to construct RO membranes that have high permeation flux as well as complete ion rejection, and that are resistant to biofilm formation.
The objective of this research was to combine zwitterion-functionalized carbon nanotubes with traditional thin film polyamide (PA) to fabricate a novel desalination membrane which has both high permeability as well as selectivity. Zwitterion functional groups in CNTs act as molecular gatekeepers at the entrance of the nanotubes to enhance blockage for salt ions. Functionalized CNTs were oriented on a membrane support by high vacuum filtration. These oriented CNTs were sealed by a polyamide film via interfacial polymerization. Cross-sectional image of the nanocomposite membrane taken by scanning electron microscopy (SEM) showed semi-aligned zwitterion-CNTs on top of a porous support covered by a thin PA film with an overall thickness of approximately 250 nm.
When the concentration of zwitterion-CNTs in the membrane increased, the nanocomposite membranes experienced significant improvement in permeation flux while the ion rejection increases slightly or remains unchanged. This indicated that the increased water flux is not due to an increase in nonspecific pores in the membrane, but rather due to an additional transport mechanism resulting from the presence of the functionalized CNTs. Significant increase of flux was also observed in separating cations other than sodium. The separation of the PA skin layer dominated the ion rejection mechanism by size exclusion even when the carbon nanotubes were introduced into the polyamide coating.
The zwitterion functional groups exposed at the membrane surface also interacted with the feed water to form a strong hydration layer, which results in improved surface biofouling resistance. The adsorption rate of protein foulants on the nanocomposite membrane surface was significantly reduced compared to the control membrane without CNTs, and the adsorbed fouling layer could be easily removed by flushing with water. After washing, the nanocomposite membrane recovered 100% of the decreased water flux whereas the control membrane only recovered 10% of the decreased flux resulting in a permanent loss of 30% in water permeation. We have therefore demonstrated that advanced materials like CNTs can be synthesized with desired functional groups, and can be embedded into traditional RO membranes to simultaneously resolve the challenge of low flux and surface fouling in the current desalination process.Ph. D.
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Wiredu, Bernard. "A novel classical synthetic approach to carbon nanotubes and their functionalized derivatives." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1706.
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Tran, Huy Nam. "Raman scattering and optical spectroscopies of individual pristine and functionalized carbon nanotubes." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS150/document.
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Ce travail, qui concerne l’étude des nanotubes de carbone mono- et double parois, comporte deux volets distincts: (i) une compréhension des propriétés optiques et phononiques intrinsèques des nanotubes de carbone individuels, (ii) une approche expérimentale originale des propriétés des nanotubes de carbone double-parois fonctionnalisés de manières covalente et non-covalente. Concernant l’étude des propriétés intrinsèques des nanotubes de carbone individuels, des informations originales ont été obtenues en couplant des résultats de spectroscopie Raman, incluant la mesure des profils d’excitation des différents modes, avec des données d’absorption optique et de diffraction électronique. De manière générale, l’approche que nous avons développée a mis en avant la complémentarité de la spectroscopie Raman et de la diffraction électronique pour l’identification « la plus probable » de la structure de chaque tube. Parmi les résultats obtenus sur les tubes mono-paroi (SWNTs) individuels, on peut souligner la confirmation originale du caractère excitonique des transitions optiques obtenue en combinant des données d’absorption et de profils d’excitation Raman, ainsi que la mise en évidence d’un comportement inattendu des rapports d’intensité des composantes LO et TO des modes G. L’étude des nanotubes de carbone double-parois (DWNTs) individuels de structures clairement identifiées a permis de comprendre le rôle de la distance inter-tubes dans les déplacements en fréquence des modes Raman (modes de respiration (RBLM) et modes G), en associant à une distance inter-tube donnée une pression interne négative (positive) quand cette distance est supérieure (inférieure) à 0.34 nm. D’autre part, le rôle des effets d’interférences quantiques dans l’évolution avec l’énergie d’excitation des intensités des composantes LO et TO des modes G a été clairement identifié. Enfin, une attribution de l’origine des transitions optiques, mesurées par spectroscopie d’absorption, de différents DWNTs a été proposée.L’étude des propriétés de DWNTs fonctionnalisés a été réalisée en couplant des expériences de spectroscopie Raman, d’absorption UV-visible-NIR et de photoluminescence (PL), incluant les cartes d’excitation de la photoluminescence (PLE), sur des suspensions de DWNTs avant et après fonctionnalisation, (i) covalente via un groupement diazonium, (ii) covalente et non-covalente (pi-stacking) par un colorant. Ce travail présente une contribution au débat sur une question essentielle pour l’utilisation des DWNTs dans des dispositifs opto-électroniques, à savoir : « les DWNTs luminescent-ils ? Et si oui, quelle est l’origine de la luminescence ? ». La présence de photoluminescence dans nos échantillons de DWNTs est établie, et l’étude de son évolution avec différents types et degrés de fonctionnalisation démontre qu’elle ne peut provenir que des tubes internes des DWNTs (PL intrinsèque aux DWNTs), ou de SWNTs générés par l’extrusion des tubes internes de DWNTs durant la préparation des suspensions. D’autre part, on peut souligner la mise en évidence d’un transfert d’énergie du colorant vers le tube interne quand le colorant est greffé de manière covalente sur la tube externeThis work concerns the study of mono- and double-walled carbon nanotubes. It contains two distinct parts: (i) the first part is devoted to the understanding of the intrinsic optical and phonon properties of individual carbon nanotubes; (ii) the second part reports an experimental investigation of the properties of covalently and non-covalently functionalized double-walled carbon nanotubes. Concerning the study of the intrinsic properties of the individual carbon nanotubes, new information was obtained by coupling Raman spectroscopy data, including the measurement of the excitation profiles of different Raman-active modes, with optical absorption and electronic diffraction data. From a general point of view, our approach put in evidence the complementarity of the Raman spectroscopy and electronic diffraction for “the most probable” assignment of the structure of the nanotubes.Among the results obtained on individual single-walled carbon nanotubes (SWNTs), one can underline the confirmation of the excitonic character of the optical transitions by combining optical absorption and Raman excitation profiles on the same nanotubes, and the evidence of an unexpected behavior of the relative intensities of the LO and TO components of the G-modes. The study of the index-identified individual double-walled carbon nanotubes has permitted to understand the role of the inter-walls distance in the frequency shifts of the radial breathing-like modes (RBLM) and G-modes, by associating a given inter-walls distance to a negative (positive) internal pressure when this distance is larger (smaller) than 0.34 nm. On the other hand, the role of quantum interferences in the evolution with the excitation energy of the intensities of the LO and TO components of the G-modes was clearly identified. Finally, the assignment of the optical transitions, measured by absorption spectroscopy, of index-identified DWNTs was proposed.The study of the properties of functionalized DWNTs was performed by combining Raman spectroscopy, UV-visible-NIR absorption and photoluminescence (PL), including maps of photoluminescence excitation (PLE), on suspensions of DWNTs before and after functionalization: (i) covalently by using diazonium, (ii) covalently and non-covalently (pi-stacking) by using dye molecules. This work is a contribution to the debate on an essential question for the use of the DWNTs in opto-electronic devices, namely: “Do the DWNTs they luminesce? And if yes, what is the origin of the luminescence?". The presence of photoluminescence in our samples of DWNTs was established, and the study of its evolution with various kinds and degrees of functionalization states that PL can only result from inner tubes (intrinsic PL of DWNTs), or from SWNTs generated by the extrusion of the internal tubes of DWNTs during the preparation of the suspensions. On the other hand, one must emphasize the evidence of an energy transfer from the dye molecules towards the internal tube when such molecules are covalently grafted on the outer tube
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Nebipasagil, Ali. "Chemically and Photochemically Crosslinked Networks and Acid-Functionalized Mwcnt Composites." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/42703.
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PTMO-urethane and urea diacrylates (UtDA, UrDA) were synthesized from a two-step reactions of bis (4-isocyanatocyclohexyl) methane (HMDI) with either α,Ï -hydroxy-terminated poly (tetramethylene oxide) (PTMO Mn 250, 1000, 2000 and 2900 g/mol) or α,Ï -aminopropyl-terminated PTMO and 2-hydroxyethyl acrylate (HEA). PTMO-based ester precursors (EtDA) were also synthesized from α,Ï -hydroxy-terminated PTMO (Mn 1000 and 2000 g/mol). Two bis acetoacetates were synthesized from acetoacetylation of 1,4-butanediol and 250 g/mol hydroxy-terminated PTMO with tert-butyl acetoacetate. 1H NMR spectroscopy confirmed the structure and average molecular weights (Mn)of diacrylates. Mn of these precursors were in the range of 950 to 3670 g/mol by 1H NMR. The rheological properties of diacrylates were studied and activation energies for flow were calculated. Activation energies increased with increasing Mn and hydrogen-bond segment content. Michael carbon addition was employed to covalently crosslink the precursors resulting in networks with gel fractions better than 90%. DSC and DMA experiments revealed that networks had a broad distribution of glass transition temperatures depending on Mn and degree of hydrogen bonding present in the diacrylates. Their Tgâ s varied from -61 ºC to 63 ºC depending on the crosslinking density and hydrogen-bonding segment content. TGA revealed that UtDA and UrDA networks had an improved thermal stability compared to their EtDA counterparts. Tensile properties showed a variation depending on the structure and Mn of diacrylate and BisAcAc precursors. The storage moduli of networks precursor change from 25.3 MPa to 2.0 MPa with increasing Mn of the urethane diacrylate Elongation at break increased from 255% to 755 % for the same networks. The Youngâ s moduli increased from 3.27 MPa for EtDA 2000 to 311.1 MPa for UrDA 2000 which was attributed to increasing degree of hydrogen-bonding.
Acid functionalization of C70 P Baytubes multiwalled carbon nanotubes (MWCNT) generated acid-functionalized nanotubes (MWCNT-COOH). Suspension of MWCNT-COOH in organic solvents (chloroform, toluene, THF, DMF and 2-propanol) were prepared. DLS indicated average particle diameters of MWCNT-COOH in DMF and in 2-propanol were 139 nm and 162 nm respectively. FESEM of suspensions revealed aggregate free dispersion of MWCNT-COOH in DMF and 2-propanol. MWCNT-COOH containing composite networks were prepared. FESEM images of fracture surfaces of UtDA showed MWCNT-COOH were well-dispersed in the composites. DMA showed an increase in the rubbery plateau modulus which correlated with the MWCNT-COOH content in the networks. Tensile testing also revealed a relationship between MWCNT-COOH content and youngâ s moduli and strain at break of networks. Storage moduli of networks increased from 25 MPa to 211 MPa with increasing MWCNT-COOH content whereas elongation at break decreased from 255 % to 146 %.
UtDAs and pentaerythritol tetraacrylate (PETA) were crosslinked under UV radiation (6 passes, 1.42 ± 0.05 W.cm2 for each pass) in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPA) (1 wt. % of the mixture) UV initiator. DMA demonstrated the presence of broad glass transition regions with a range of Tgâ s which varied from -60 °C to -30°C. Tensile testing also revealed the relationship between Youngâ s moduli, strain at break and the molecular weight of the diacrylates. The increasing molecular weight of urethane diacrylate precursors caused a drop in the storage moduli of networks from 15.8 MPa to 1.4 MPa and an increase in elongation at break from 76 % to 132 %.Master of Science
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Nitschke, Annika. "Investigation of Polymer-Filler Interactions Using Functionalized Nanoparticles." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1363-6.
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Kurkina, Tetiana [Verfasser]. "Label-free electrical biosensing based on electrochemically functionalized carbon nanostructures / Tetiana Kurkina." Gießen : Universitätsbibliothek, 2012. http://d-nb.info/1064173438/34.
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Liu, Jiayi. "Development and Applications of Functionalized Octatetrayne as Novel Carbon Media in Chromatography." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1519322396476316.
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Heister, Elena. "Functionalized carbon nanotubes as a multimodal drug delivery system for target cancer therapy." Thesis, University of Surrey, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529424.
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Surapathi, Anil Kumar. "Functionalized Single Walled Carbon Nanotube/Polymer Nanocomposite Membranes for Gas Separation and Desalination." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/40297.
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Polymeric membranes for gas separation are limited in their performance by a trade-off between permeability and selectivity. New methods of design are necessary in making membranes, which can show both high permeability and selectivity. A mixed matrix membrane is one such particular design, which brings in the superior gas separation performance of inorganic membranes together with the easy processability and price of the polymers. In a mixed matrix membrane, the inorganic phase is dispersed in the polymeric continuous phase. Nanocomposite membranes have a more sophisticated design with a thin separation layer on top of a porous support.
The objective of this research was to fabricate thin SWNT nanocomposite membranes for gas separation, which have both high permeability and selectivity. SWNT/polyacrylic nanocomposite membranes were fabricated by orienting the SWNTs by high vacuum filtration. The orientation of SWNTs on top of the porous support was sealed by UV polymerization. For making these membranes, the CNTs were purified and cut into small open tubes simultaneously functionalizing them with COOH groups. Gas sorption of CO2 in COOH functionalized SWNTs was lower than in purified SWNTs. Permeabilities in etched membrane were higher than Knudsen permeabilities by a factor of 8, and selectivities were similar to Knudsen selectivities.
In order to increase the selectivities, SWNTs were functionalized with zwitterionic functional groups. Gas sorption in zwitterion functionalized SWNTs was very low compared to in COOH functionalized SWNTs. This result showed that the zwitterionic functional groups are kinetically blocking the gas molecules from entering the pore of the CNT. SWNT/polyamide nanocomposite membranes were fabricated using the zwitterion functionalized SWNTs by interfacial polymerization. The thickness of the separation layer was around 500nm. Gas permeabilities in the CNT membranes increased with increasing weight percentage of the SWNTs. Gas permeabilities were higher in COOH SWNT membrane than in zwitterion SWNT membrane. Gas selectivities were similar to the Knudsen selectivities, and also to the intrinsic selectivities in the pure polyamide membrane.
The water flux in SWNT-polyamide membranes increased with increasing weight percentage of zwitterion functionalized SWNTs, along with a slight increase in the salt rejection. Membranes exhibited less than 1% variability in its performance over three days.Ph. D.
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Olevik, David. "Laser induced effects in carbon nanotubes : implications for Raman characterization of functionalized systems." Licentiate thesis, Luleå : Luleå University of Technology, 2009. http://pure.ltu.se/ws/fbspretrieve/2724954.
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Gupta, Ashim. "Evaluation of Non-functionalized Single Walled Carbon Nanotubes Composites for Bone Tissue Engineering." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/dissertations/819.
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Introduction: Bone defects and non-unions caused by trauma, tumor resection, pathological degeneration, or congenital deformity pose a great challenge in the field of orthopedics. Traditionally, these defects have been repaired by using autografts and allografts. Autografts have set the gold standard for clinical bone repair because of their osteoconductivity, osteoinductivity and osteogenicity. Nevertheless, the application of autografts is limited because of donor availability and donor site morbidity. Allografts have the advantage that the tissues are readily available and can be easily applied, especially when large segments of bone are to be reconstructed. However, their use is also limited by the risk of disease transfer and immune rejection. To circumvent these limitations tissue engineering has evolved as a means to develop viable bone grafts. An ideal bone graft should be both osteoconductive and osteoinductive, biomechanically strong, minimally antigenic, and eliminates donor site morbidity and quantity issues. The biodegradable polymer, Poly lactic-co-glycolic acid (PLAGA) was chosen because of its commercial availability, biocompatibility, non-immunogenicity, controlled degradation rate, and its ability to promote optimal cell growth. To improve the mechanical properties of PLAGA, Single Walled Carbon Nanotubes (SWCNT) were used as a reinforcing material to fabricate composite scaffolds. The overall goal of this project is to develop a Single Walled Carbon Nanotube composite (SWCNT/PLAGA) for bone regeneration and to examine the interaction of MC3T3-E1 cells (mouse fibroblasts) and hBMSCs (human bone marrow derived stem cells) with the SWCNT/PLAGA composite via focusing on extracellular matrix production and mineralization; and to evaluate its toxicity and bio-compatibility in-vivo in a rat subcutaneous implant model. We hypothesize that reinforcement of PLAGA with SWCNT to fabricate SWCNT/PLAGA composites increases both the mechanical strength of the composites as well as the cell proliferation rate on the surface of the composites while expressing osteoblasts phenotypic, differentiation and mineralization markers; and SWCNT/PLAGA composites are biocompatible and non-toxic, and are ideal candidates for bone tissue engineering. Methods: PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40 and 100mg), characterized and degradation studies were performed. PLAGA (poly lactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated; characterized and mechanical testing was performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Sprague-Dawley rats were implanted subcutaneously with Sham, poly lactic-co-glycolic acid (PLAGA) and SWCNT/PLAGA composites, and sacrificed at 2, 4, 8 and 12 week post-implantation. The animals were observed for signs of morbidity, overt toxicity, weight gain, food consumption, hematological and urinalysis parameters, and histopathology. Results: Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Composites with 10mg SWCNT resulted in highest rate of cell proliferation (p<0.05) among all composites. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of 10mg SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, non-stressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared to PLAGA. No mortality and clinical signs were observed. All the groups showed consistent weight gain and rate-of-gain for each group was similar. All the groups exhibited similar pattern for food consumption. No difference in urinalysis parameters, hematological parameters; and absolute and relative organ weight was observed. A mild to moderate summary toxicity (sumtox) score was observed for animals treated with the PLAGA and SWCNT/PLAGA whereas the sham animals did not show any response. At all the time intervals both PLAGA and SWCNT/PLAGA showed a significantly higher sumtox score compared to the Sham group. However, there was no significant difference between PLAGA and SWCNT/PLAGA groups. Conclusion: Our SWCNT/PLAGA composites, which possess high mechanical strength and mimic the microstructure of human trabecular bone, displayed tissue compatibility similar to PLAGA, a well known biocompatible polymer over the 12 week study. Thus, the results obtained demonstrate the potential of SWCNT/PLAGA composites for application in BTE and musculoskeletal regeneration. Future studies will be designed to evaluate the efficacy of SWCNT/PLAGA composites in bone regeneration in a non-union ulnar bone defect rabbit model. As interest in carbon nanotube technology increases, studies must be performed to fully evaluate these novel materials at a nonclinical level to assess their safety. The ability to produce composites capable of promoting bone growth will have a significant impact on tissue regeneration and will allow greater functional recovery in injured patients.
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Clément, Pierrick. "Functionalized carbon nanotubes for detecting traces of benzene vapours employing screen-printed resistive and resonant transducers." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/364789.
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Capes de nanotubs de carboni de múltiples parets (MWCNTs) s'han dipositat sobre diferents substrats transductors per a aplicacions de detecció de gasos. MWCNTs tractats amb plasma d'oxigen, anomenats O-MWCNTs, han estat un element fonamental per al desenvolupament de nanomaterials sensibles a diferents gasos. Inicialment, els O-MWCNTs es van estudiar com a element sensible en dispositius sensors de gasos de tipus resistiu. Els compostos orgànics volàtils (COV) com ara benzè, toluè, etanol, metanol i acetona es van utilitzar per a caracteritzar aquesta capa sensible. Els sensors van mostrar bona sensibilitat i excel·lent recuperació de la línia de base en presència de vapors de benzè o toluè en comparació amb els altres VOCs estudiats. També, els O-MWCNTs es van estudiar com a nanomaterials adsorbents dipositats en micropalanques ressonants piezoelèctriques PZT fabricades per serigrafia. En un segon pas, es va modificar l'elèctrode superior per convertir-lo en interdigitat amb la finalitat d'obtenir un transductor que permetir emprar dos mecanismes de transducció. Aquesta configuració ens va permetre mesurar, per a un sol dispositiu, el canvi de resistència de la pel·lícula de nanotubs de carboni i el canvi de freqüència de ressonància de la micropalanca PZT després de l'exposició a compostos orgànics volàtils. Les propietats de detecció de tals sistemes han estat estudiades per contaminants com el benzè, CO i NO2. Canvis positius i negatius de la freqüència de ressonància s'observen en baixes i altes concentracions de gas, respectivament. Aquests s'atribueixen a que l'estrès o els efectes de massa es fa dominant en nivells baixos o alts de concentració de gas. Mitjançant el signe del canvi de la resistència de la pel·lícula de O-MWCNT es poden discriminar els gasos o vapors d'acord al seu caràcter oxidant o reductor. L'interès de la doble transducció s'ha demostrat en la detecció de CO. Finalment, al davant de la dificultat per detectar benzè en concentracions baixes, s'ha seguit un enfocament diferent, basat en reconeixement molecular hoste-amfitrió. Per promoure la interacció específica cap al benzè, s'ha emprat un cavitant (quinoxalina) per funcionalitzar els O- MWCNTs. La detecció de 2,5 ppb de benzè en l'aire sec es demostra com a possible i el límit de detecció (LOD), es troba prop de 600 ppm.Capas sensibles basadas en nanotubos de carbono multi pared (MWCNTs) han sido depositadas sobre diferentes sustratos de transductores para su aplicación en sensores de gases. MWCNTs tratados con plasma de oxígeno, llamados O-MWCNTs, han sido el compuesto básico para el desarrollo de otros nanomateriales sensibles a gases. Primero, O-MWCNTs fueron estudiados como sensores de gas resistivos. Compuestos orgánicos volátiles (COVs) como benceno, tolueno, etanol, y acetona fueron usados para caracterizar esta capa sensible. Los sensores muestran una buena sensibilidad y una recuperación excelente de la línea de base en presencia de vapores de benceno o tolueno en comparación a otros COVs probados. O-MWCNTs fueron estudiados como nanomateriales adsorbentes depositados sobre micropalancas resonantes piezoeléctricas de PZT fabricadas por serigrafía multi-capa. En segundo término, una modificación del electrodo superior en forma de dos electrodos interdigitados fue implementada con el objetivo de obtener un elemento transductor capaz de implementar dos mecanismo de transducción. Esta configuración nos ha permitido medir, con un solo dispositivo, el cambio en la resistencia de la capa de los nanotubos de carbono y el desplazamiento de la frecuencia de resonancia de la micropalanca PZT bajo exposicion a los COVs. Las propiedades de detección de estos sistemas han sido estudiadas para los contaminantes benceno, CO y NO2. Desplazamientos positivos y negativos de la frecuencia de resonancia son observados a bajas y altas concentraciones, respectivamente. Esto es atribuido a los efectos de estrés y de masa convirtiéndose en dominantes a bajos o altos niveles de concentración. Monitorizando la resistencia de la capa de los O-MWCNTs de tipo-p ayuda a discriminar los gases/vapores en acuerdo con sus caracteres oxidante o reductor. El interés de la doble transducción ha sido demostrado con la detección de CO. Finalmente, frente a la dificultad de detectar benceno a baja concentración, un enfoque diferente basado en el reconocimiento molecular "host-guest" es propuesto. Para promover interacciones especificas hacia el benceno, los MWCNTS funcionalizados con un cavitando de tipo quinoxalina fueron empleados. Una detección de 2.5 ppb de benceno en aire seco es demostrado con un límite de detección (LOD) cerca de 600 ppt.
Multiwall carbon nanotubes (MWCNTs) base sensitive layers have been deposited onto different transducer substrates for gas sensing application. Oxygen plasma treated MWCNTs, so-called O-MWCNTs, have been a building block for developing other gas sensitive nanomaterials. At first, O-MWCNTs were studied as resistive gas sensors. Volatile organic compounds (VOCs) such as benzene, toluene, ethanol, methanol and acetone were used to characterize this sensitive layer. The sensors showed good sensitivity and excellent baseline recovery in the presence of benzene or toluene vapors compared to the others tested VOCs. O-MWCNTs were studied as adsorbent nanomaterials deposited on PZT piezoelectric resonant cantilevers fabricated by multilayer screen-printing. In the second step, a modification of the top electrode to become an interdigitated electrode was implemented in order to have a sensor transducer employing two transduction mechanisms. This configuration allowed us to measure, for a single device, the resistance change of the carbon nanotube film and the resonance frequency shift of the PZT cantilever upon exposure to VOCs. The sensing properties of such systems have been studied for benzene, CO, and NO2 contaminants. Positive and negative shifts of the resonance frequency are observed at low and high gas concentrations, respectively. These are attributed to stress or to mass effects becoming dominant at low or high gas concentration levels. Monitoring the resistance of the p-type O-MWCNT film helps discriminating gases/ vapours according to their oxidizing or reducing character. The interest of the double transduction has been demonstrated in the detection of CO. Finally, in front of the difficulty to detect benzene at low concentrations, a different approach based on the host-guest molecular recognition is proposed. To promote specific interaction toward benzene, quinoxaline-walled thioether-legged deep cavitand functionalized MWCNTs are used. The detection of 2.5 ppb of benzene in dry air is demonstrated with a limit of detection (LOD) near 600 ppt.
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Solares, Rivera Santiago de Jesus Goddard William A. "Multi-scale simulations of single-walled carbon nanotube atomic force microscopy and density functional theory characterization of functionalized and non-functionalized silicon surfaces /." Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-05122006-102528.
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Kong, Na. "Carbohydrate-Functionalized Nanomaterials : Synthesis, Characterization and Biorecognition Studies." Doctoral thesis, KTH, Organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172990.
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This thesis focuses on the development of carbohydrate coupling chemistry on nanomaterials and their biological activity studies. It is divided into two parts: In part one, two carbohydrate immobilization approaches, based on perfluorophenyl azide (PFPA)-functionalized silica nanoparticles (SNPs), are presented, where the binding affinity of the glyconanoparticles was evaluated through carbohydrate-lectin interaction. In the first approach, PFPAfunctionalized SNPs were treated with propargylated glycosides and functionalized under copper-catalyzed azide-alkyne cycloaddition (CuAAC) conditions to give glyconanoparticles. For the second approach, a metal-free coupling chemistry based on perfluorophenyl azide-aldehyde-amine cycloaddition (AAAC) was developed for carbohydrate immobilization on PFPA-functionalized SNPs using glycosyl amine and phenylacetaldehyde. Subsequently, a quantitative fluorine nuclear magnetic resonance (19F qNMR) technique was developed to determine the carbohydrate density on the glyconanoparticles. The addition of an internal standard allowed the accurate determination of carbohydrate density, which was then used to calculate the apparent dissociation constant (Kd ) of the glyconanoparticles with lectin by a ligand competition assay. The developed approaches proved general and versatile, and the carbohydrate-presenting nanoplatforms showed high binding specificity in lectin binding. In part two, microwave irradiation was used to functionalize carbon nanomaterials with PFPA followed by carbohydrate conjugation. The microwave-assisted method proved efficient for a number of carbon nanomaterials including carbon nanotubes (CNTs), graphene and fullerene. The carbohydrates on the glyconanomaterials retained their binding patterns towards cognate lectins.QC 20150907
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Bernhardt, Sebastian. "Magnesium halide-mediated addition of functionalized organozinc reagents to aldehydes, ketones and carbon dioxide." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-147538.
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Burns, Daniel James. "On single-molecule DNA sequencing with atomic force microscopy using functionalized carbon nanotube probes." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32520.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 91-103).
A novel DNA sequencing method is proposed based on the specific binding nature of nucleotides and measured by an atomic force microscope (AFM). A single molecule of DNA is denatured and immobilized on an atomically fiat surface, and a force probe functionalized with a nucleotide is scanned along the molecule to detect locations of the probe nucleotide's complement. To increase the spatial resolution of the atomic force microscope so that individual bases can be distinguished, a single-walled carbon nanotube is grown from the AFM probe and functionalized with a single nucleotide. The carbon nanotube diameter is of the order as the nucleotide base spacing--providing the necessary spatial resolution for single molecule sequencing. The absolute force detection limit of the microscope is thermal noise-limited and derived herein from the equipartition theorem. The calculated minimum detectable force is less than experimentally obtained nucleotide binding forces, indicating that the AFM is capable of directly measuring single nucleotide interactions. A model of the oscillating AFM probe dynamics is developed, allowing a methodical approach to determining attractive forces with a chemically-specific sensor. This attractive force detection is performed by measuring the phase lag of the oscillating probe near the sample surface as compared to the resonating probe in free air. As grown, the carbon nanotubes are too long to be used as reliable force probes, therefore a method for shortening carbon nanotubes is presented utilizing high voltages to remove material. Measuring the length of the nanotube is performed with a novel technique that exploits the nanotube's unique elastic buckling property.
(cont.) This measurement technique characterizes the length of the nanotube while the probe is still mounted on the AFM and alleviates the need for a secondary microscope. The shortening procedure developed is performed in conjunction with the nucleotide functionalization, creating a precise and chemically-specific force probe. Experiments are performed on synthetic DNA of a known sequence to validate the proposed approach. A functionalized carbon nanotube force probe is scanned along single molecules of synthetic DNA to determine locations of target bases.
by Daniel J. Burns.
S.M.
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White, Madeleine Michael Isabella. "Optimization and Longevity of Functionalized Multi-Walled Carbon Nanotube-Enabled Membranes for Water Treatment." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2174.
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Water scarcity is a growing concern at the global scale. Large scale water reuse is growing both in necessity and popularity. Before water reuse can be performed efficiently on a large scale or be used for potable supply, even indirectly, contaminants of emerging concern (CECs) will need to be treated at the full scale. Advanced oxidation processes (AOPs) are a form of advanced water treatment capable of treating a wide range of CECs. This study contributes to the growing field of AOPs and more specifically AOPs using ozone combined with functionalized multi-walled carbon nanotubes (MWCNTs). Ozonation of MWCNTs has been found to increase hydroxyl radical production and improve AOP treatment. Novel MWCNT-enabled membranes were used as catalysts for ozonation to degrade the CEC Atrazine. Atrazine is an ozone recalcitrant CEC that is commonly found in herbicides. Atrazine removal results, found using a high-performance liquid chromatograph (HPLC), were inconsistent between membranes constructed using identical procedures. Further analysis using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopes (SEM), and UV-Vis spectrophotometry was conducted to explore inconsistencies in construction of the membranes which might explain removal inconsistencies and predict membrane longevity. Removal was found to be influenced by filtration time and ozone exposure. Ozone exposure and filtration time influence percent removal because they both affect hydroxyl formation. The membrane test filtration duration, for equal filtered volumes, ranged from under 5 minutes to nearly an hour. It is believed that filtration time inconsistency was due to inconsistent MWCNT loading on the surface of the membranes. Extended exposure to ozone might change the surface chemistry of the MWCNTs on the membrane surface, affecting hydroxyl radical production. Additionally, repeated use of the membrane created surface defects that might reduce the membrane strength. This study found that the lifetime of the membrane is far past what was simulated in lab and further testing must be performed.
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Clément, Pierrick. "Functionalized carbon nanotubes for detecting traces of benzene vapors employing screen-printed resistive and resonant transducers." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0127/document.
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Ce travail de thèse porte sur l’optimisation des propriétés de nanotubes de carbone pour la détection de gaz.Pour cette application, les nanotubes de carbone ont été déposés sur deux types de transducteur sérigraphiés, résistif et résonant. Les nanotubes de carbone à multi-parois traités par plasma d’oxygène (O-MWCNTs) ont été le point de départ de ces travaux. Les performances de ces nanomatériaux déposés par air-brushing sur le transducteur de type résistif comportant deux électrodes de platine interdigitées préalablement déposées sur un substrat d’alumine ont été étudiées en présence de composés organiques volatils (COVs). Par comparaison aux réponses obtenues sous éthanol et acétone,une meilleure sensibilité et un meilleur temps de recouvrement ont été observés en présence de benzène et de toluène. Les nanotubes de carbone O-MWCNTs ont été ensuite déposés sur une micropoutre piézoélectrique sérigraphiée. Cette dernière, à base de PZT placé entre 2 électrodes, permet simultanément l’actionnement et la mesure de sa fréquence de résonance. De plus, le remplacement de l’électrode supérieure de géométrie rectangulaire par deux électrodes interdigitées a permis la mesure simultanée de la résistance des nanotubes de carbone et de la fréquence de résonance. Grâce à cette nouvelle génération de transducteur, la variation de résistance de la couche de nanotubes de carbone et la variation de masse ont pu être mesurés en présence de COVs mais aussi de monoxyde de carbone et de dioxyde d’azote. Sous forte concentration de vapeurs/gaz, la prise de masse de la couche sensible entraîne des variations de fréquence négatives. En revanche, à plus faible concentration, des variations de fréquence positives ont été observées. Ce phénomène est attribué à une modification de la rigidité de la poutre résonante suite à l’adsorption sur la poutre de l’espèce à détecter enfaible quantité. La mesure simultanée de la résistance des OMWCNTs de type-p a de plus permis la discrimination du caractère oxydant ou réducteur des gaz/vapeurs. Finalement,face à la difficulté de détecter le benzène à faible concentration, une approche basée sur la reconnaissance moléculaire « host-guest » a été proposée. Afin de promouvoir des interactions spécifiques avec le benzène, les MWCNTs ont été fonctionnalisés avec une molécule de type quinoxaléine en conformation de cavité. Ainsi, la mesure de la résistance de ce nanomatériau hybride a permis la détection de 2,5 ppb de benzène sous air sec avec une limite de détection (LOD) proche de 600 ppt. Ces résultats remarquables démontrent les potentialités des nanotubes de carbone fonctionnalisés pour la détection de faibles traces de composés aromatiquesMultiwall carbon nanotubes (MWCNTs) base sensitive layers have been deposited onto different transducer substrates for gas sensing application. Oxygen plasma treated MWCNTs, so-called O-MWCNTs, have been a building blockfor developing other gas sensitive nanomaterials. At first, OMWCNTs have been studied as resistive gas sensors. Volatile organic compounds (VOCs) such as benzene, toluene, ethanol, methanol and acetone have been used to characterize this sensitive layer. The sensors show good sensitivity and excellent baseline recovery in the presence of benzene or toluene vapors compared to the others tested VOCs. OMWCNTs have been studied as adsorbent nanomaterials deposited on PZT piezoelectric resonant cantilevers fabricated by multilayer screen-printing. In the second step, a modification of the rectangular top electrode to become an interdigitated electrode was implemented in order to have a sensor transducer employing two transduction mechanisms. This configuration allowed us to measure, for a single device, the resistance change of the carbon nanotube film and the resonance frequency shift of the PZT cantilever up on exposure to VOCs. The sensing properties of such systems have been studied for benzene, CO, and NO2 contaminants. Positive and negative shifts of the resonance frequency are observed at lowand high gas concentrations, respectively. These are attributed to stress or to mass effects becoming dominant at low or high gas concentration levels. Monitoring the resistance of the p type O-MWCNT film helps discriminating gases/ vapours according to their oxidizing or reducing character. The interest of the double transduction has been demonstrated in the detection of CO. Finally, in front of the difficulty to detect benzene at low concentrations, a different approach based on the host-guest molecular recognition is proposed. To promote specific interaction toward benzene, quinoxaline-walled thioether-legged deep cavit and functionalized MWCNTs are used. The detection of 2.5 ppb of benzene in dry air is demonstrated with a limit of detection (LOD) near 600 ppt.These remarkable results show the potentiality of functionalized carbon nanotubes in aromatic vapor sensing at traces level
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Jasim, Nuralhuda Aladdin. "THE PROPERTIES OF NATURAL ORGANIC MATTER (NOM) AFFECT THE IMPACT OF NON-FUNCTIONALIZED AND FUNCTIONALIZED MULTI-WALLED CARBON NANOTUBES (MWCNTS) ON TOMATO PLANTS (SOLANUM LYCOPERSICUM)." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1299.
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Due to the high specific surface area and aspect ratio (length to diameter ratio, or L/D) of carbon nanotubes, they tend to bind strongly through the van der Waals interactions prevailing among tubes. Thus, they agglomerate and settle in water to form large conglomerates. The adsorption of natural organic matter (NOM) or surfactants onto raw multi-walled carbon nanotubes (MWCNTs) was shown to effectively enhance the dispersibility and stabilization of MWCNTs. The two kinds of dispersants used were humic acid and peptone. Also, two functionalized MWCNTs (-OH and -COOH functional groups) were also dispersed in humic acid (HA) to evaluate the effect of surface property on CNT biological interactions. Based on the dynamic light scattering (DLS) analyses, the use of surfactants increased the steric hindrance as well as the charge repulsion between adjacent CNT particles, thereby enhancing their suspension. HA and peptone sorption onto the surface of MWCNTs can cover their hydrophobic surfaces and help stabilize CNTs. Furthermore, hydroxyl modification of MWCNTs resulted in stable dispersions in water containing HA at 10 and 1000mg/L, while COOH-MWCNT suspensions displayed stable dispersion with lower negative surface charges solely at 100g/L. While, TEM images agreed with the DSL analysis that HA-stabilized MWCNTs were well-dispersed compared to pep-stabilized MWCNTs. Both f-MWCNT types showed a significant reduction in agglomerates as compared to the non-functionalized one. It was noted that the dispersion state as well as the surface properties of both MWCNTs and f-MWCNTs plays an effective role in the potential toxic effects of CNTs. Decreases in the growth rate, chlorophyll index, water uptake, dry weight, and root elongation rate along with a rise in mortality were detected as an indication of phyto-toxicity in both the pep-MWCNT suspensions at 1000mg/L and the peptone control seedlings in contrast to the seedlings treated with pep-MWCNTs at 10 and 100mg/L doses . This was an indicator for the presence of suspended MWCNTs as well as their unstable dispersion in the water column. However, the interaction between the HA-CNTs and the plants improved development in terms of water uptake, growth rate, chlorophyll index, dry weight and root elongation rate due to their well- dispersed stability in water. There were no differences among the f-MWCNT, MWCNT and HA plant groups in terms of their quantum yield and chlorophyll content. While the f-MWCNTs significantly enhanced the plants' growth, water transpiration, and dry root and shoot weight as compared to the non-functionalized MWCNTs. It appeared that exposure to OH-MWCNTs improved the development of tomatoes in terms of water uptake, root elongation rate, and growth rate as well as light- and dark-adaptation, whereas COOH-MWCNTs and non-functionalized MWCNTs were apparently toxic in terms of root leakage and dark-adaptation. Overall, our results suggest that the surface properties of CNTs associated with their dispersion stability specify their influence on the growth of tomato plants. Moreover, the nature of the dispersant agent itself plays an active role in the toxicity of MWCNTs on tomatoes. Our investigation indicated that there is a significant correlation between the toxicity of unfunctionalized MWCNTs and f-MWCNTs and the toxicity of the dispersant agent.
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Kenney, Floyd E. "Biosensor Production By Conjugation Of HSA-Specific Peptide To Functionalized Nanotube Fiber." Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1525360589515967.
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Van, den Hoven Bernard G. "New innovations in rhodium catalyzed transformation of alpha-functionalized alkynes utilizing carbon monoxide and hydrogen." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6322.
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Identifying the important roles that functional groups play when substituted alkynes are placed under hydroformylation conditions (reactions incorporating carbon monoxide and hydrogen gas with catalytic amounts of a rhodium complex) is a valuable tool for organic synthesis. Novel and unexpected chemistry have resulted from establishing the primary and secondary roles of certain functional groups. The primary role is the ability to direct a rhodium complex to add to a triple bond, and the secondary role involves directing the type of chemistry that will take place after the addition. The following examples demonstrate this dual relationship resulting in the preparation of alpha,beta-unsaturated aldehydes, N-heterocyclec enols, and important ring systems with potential biological activity. The selected 5-membered heterocycles generated are important materials in treating inflammatory diseases, cancer and heart disease, as well as allowing for the inhibition of HIV protease. The reaction of aliphatic 1-en-3-ynes with synthesis gas in the presence of the zwitterionic rhodium complex, (eta6-C6H 5BPh3)-Rh+(1,5-COD) and triphenyl phosphite afford formyl-dienes in high regioselectivity, and in 50 to 70% isolated yields. As well, the hydroformylation of 2-acetylenic thiophenes afford, as the major product, the alpha,beta-unsaturated aldehyde with the aldehyde and thiophene attached to the same olefin carbon atom. Excellent regioselectivities of 64 to 100% and additive yields of 65 to 97% were obtained when the acetylenic unit is a propargyl ether or ester, phenylacetylene, or an enyne. alpha-Keto alkynes react with CO/H2 in the presence of catalytic quantities of the zwitterionic rhodium complex and triphenyl phosphite to form either the 2-, 2(3H)- or 2(5H)-furanones in 61--93% yields. In addition, the tandem cyclohydrocarbonylative/CO insertion of alpha-imino alkynes afford aldehyde substituted pyrrolinones in 67 to 82% yields. Hydrocarbonylative enolation of 2-acetylenic thiazoles in the presence of CO, H2 and catalytic quantities of the zwitterionic rhodium complex and triphenyl phosphite afford (Z)-2-thiazol-2-ylalk-1en-1ols in 61 to 90% yields. The extension of the hydrocarbonylative enolation to 2-acetylenic benzoxazoles give (Z)-2-benzoxazol-2-ylalk-1-en-1-ols in 37 to 87% yields.
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Twomey, John Ryan. "Characterization of nanocomposite scaffolds composed of collagen and functionalized carbon nanotubes for tissue engineering applications." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447691.
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Su, Xin. "NOVEL DESIGN OF FUNCTIONALIZED CARBON NANOTUBE ELECTRODES AND MEMBRANES FOR FUEL CELLS AND ENERGY STORAGE." UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/5.
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A novel electrochemical method to generate nm-scale bubbles at the tips of CNTs can temporarily block the membrane. A 92% blocking efficiency is achieved when the bubbles are stabilized in 30-60 nm diameter „wells‟ at the tips of CNTs. This well is formed by the electrochemical oxidation of the conductive CNTs partially into the polymer matrix of the membrane. Meanwhile, the nanoscale bubbles can be removed with 0.004 atm pressure to recover the transport through the CNT membrane. The CNT membrane with nanoscale bubble valve system was used to demonstrate electrochemical energy storage.
Uniform ultrathin Pt films were electrodeposited onto an aligned array of carbon nanotubes (CNTs) for high-area chemically stable methanol fuel cell anodes. Electrochemical treatment of the graphitic CNT surfaces by diazonium benzoic acid allowed for uniform Pt electroplating. The mass activity of the Pt thin film can reach 400 A/g at a scan rate of 20 mV/s and in a solution of 1 M CH3OH/0.5 M H2SO4. A novel programmed pulse potential at 0 V was also seen to nearly eliminate the effects of carbon monoxide poisoning on catalyst Pt. Furthermore, the Pt monolayer was deposited on buckypaper by replacing the precursor Cu monolayer coated on CNTs by the underpotential deposition. The electrochemical surface modification of graphite CNTs by fluorinated benzoic acid was critical to coordinate Cu ions for monolayer formation. The mass activity of the monolayer can be improved to the record value of 2711 A/g. This is about 13 times higher than that of the ~10 nm thick Pt film coated on MWCNTs. Besides the high mass activity, the Pt monolayer coated on buckypaper can be used as catalyst for fuel cells with several advantages such as low cost, high surface area, flexibility, mechanical robustness and enhanced pressure flow.
Finally, a new strategy has been developed toward electrochemical water oxidation with Ir complexes catalyst, which was grafted on buckypaper by direct binding to enhance catalyst activity. The TOF (turn over frequency) of the Ir catalyst for water splitting was 7.9 s-1 at the constant potential of 1.4 V vs Ag/AgCl.
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Zhou, Zhengping. "Synthesis and Characterization of Novel Hierarchically Functionalized Carbon Nanofibers for Energy Conversion and Storage Applications." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27241.
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Among various energy conversion and storage devices available in the market, supercapacitors are deemed as an effective, competitive solution to the increasing demand for high-power density energy-storage devices. Yet, supercapacitors usually carry relatively low energy density compared to batteries. Nanostructured electrode materials are expected being able to greatly enhance the electrochemical performance of supercapacitors. This research aims at rational synthesis and electrochemical characterization of novel hierarchically functionalized carbon nanofibers (CNFs) for use as advanced electrode materials of supercapacitors. These novel CNFs [(i.e., graphene-beaded CNFs (G/CNFs) and carbon nanotube (CNT)-grown CNFs (CNT/CNFs)] were successfully synthesized. The unique synthesis routes consist of electrospinning the precursor polymer nanofibers, followed by controlled carbonization, chemical vapor deposition (CVD) for CNT growth, and in situ polymerization for coating nanostructured conducting polymer. These new electrode materials carry the advantages of G/CNFs and CNT/CNFs (e.g., unique nanostructural continuity, large specific surface area, low intrinsic contact electric resistance, etc.) and conducting polymers (e.g., high pseudocapacitance), and therefore show excellent electrochemical performance including high specific capacitance, superior energy and power densities, and excellent cyclability. In addition, this work also provides the experimental study on parameter dependency of conic angle in electrospinning and scalable fabrication of core-shell nanofibers via needleless emulsion electrospinning.DOE EPSCoR IIP Program - Sustainable Energy Seed Grants Initiative (SUNRISE); National Science Foundation (NSF); North Dakota NASA EPSCoR; North Dakota Soybean Council; ND EPSCoR Doctoral Dissertation Fellowship
National Science Foundation (NSF)
DOE EPSCoR
ND NASA EPSCoR
North Dakota Soybean Council
ND EPSCoR Doctoral Dissertation Fellowship
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Requardt, Hendrik [Verfasser]. "Polyethylene Glycol functionalized Multi Walled Carbon Nanotubes for Nanomedical application as Drug Carriers / Hendrik Requardt." Hannover : Bibliothek der Tierärztlichen Hochschule Hannover, 2017. http://d-nb.info/115034105X/34.
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Yamamoto, Hiroki. "Syntheses, Structures, and Applications of Inorganic Materials Functionalized by Fluorine." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263756.
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Riaz, Ali 1981. "Functionalized polyhedral oligomeric silsesquioxane (POSS) for incorporation of chemically pendant chains = Utilização de silsesquioxanos oligoméricos poliédricos funcionalizados (POSS) no ancoramento de cadeias orgânicas à superfície." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250644.
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Orientador: José de Alencar SimoniTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Este trabalho apresenta a síntese e caracterização de compostos silsesquioxanos gaiola cúbica (POSS) com cadeias orgânicas pendentes. O projeto foi iniciado com a idéia de sintetizar os silsesquioxanos cúbicos com cadeias organofuncionalizadas ancoradas, capazes de capturar os metais pesados, corantes e CO2. Mas foram enfrentadas algumas dificuldades como baixo rendimento (30-37%) e longo tempo de reação (5-35 dias). As reações foram investigadas para melhorar o rendimento, bem como para reduzir o tempo de reação. Algumas modificações em rotas de reação foram introduzidas, o que trouxe melhorias notáveis nos resultados, onde o rendimento aumentou cerca de 64 % e o tempo de reação foi reduzido para 24 horas em média. Na sequência, os produtos sintetizados foram caracterizados para elucidar suas estruturas, utilizando diferentes técnicas físicas tais como FTIR, CHN, XRD, MEV, TGA, 13CNMR e 29SiNMR no estado sólido, onde as gaiolas Si-O de todos os compostos foram evidenciadas por meio de 29SiRMN e dos seus espectros de FTIR, enquanto as cadeias ancorados às gaiolas de POSS foram confirmadas utilizando os resultados de 13CRMN, juntamente com seus respectivos espectros de FTIR. Os compostos sintetizados também foram testados quanto à sua estabilidade térmica utilizando a técnica de TGA. Após a otimização da síntese de silsesquioxanos cúbicos, os híbridos PAA-13-3, PAA-MTC e PAA-Ph foram avaliados por suas habilidades de captação de cátions bivalentes, tais como Cu2+, Cd2+ e Pb2+ de suas soluções aquosas, sendo que o Cu2+ apresentou maior afinidade de sorção em relação aos dois metais. Estes sistemas de sorção foram analisados através ICP-OES. Para explicar o comportamento de sorção destas amostras alguns modelos estatísticos como Langmuir, Freundlich, Temkin e Redlich-Peterson foram aplicadas, onde os dados de sorção de Cu2+ em PAA-13-3 foram melhor ajustados pelo modelo Langmuir, mostrando ser uma sorção monocamada, enquanto que no caso do PAA-MTC e PAA-Ph modelo de melhor ajuste foi o Freundlich, confirmando a sorção de múlti camadas. Um dos materiais sintetizados (PAA-13-3) foi avaliado quanto à sua capacidade de adsorver CO2 gasoso, mostrando-se promissor na remoção de CO2, mesmo a baixas pressões (máx. 100 mm Hg). A adsorção de CO2 no material também foi estudada por calorimetria de adsorção gás-sólido, em um calorímetro especialmente desenvolvido para tal, observando-se valores de entalpia de adsorção entre -36 e -7 kJ mol-1
Abstract: This report presents the synthesis and characterization of POSS compounds having cubic silsesquioxane cage to which the organic pendant chains are anchored. The project was started with the idea to synthesize the cubic silsesquioxanes with organofunctionalized pendant chains, which are able to capture heavy metals, dyes and some acids like CO2. But in the beginning the hurdles like low % yields (30-37 %) and long reaction times (5-35 days) were to be faced. The reactions were worked out to enhance the % yields as well as to reduce the reaction time. Some modifications in reaction routes have been introduced, which brought up remarkable improvements in the results, where yield was increased upto 64 % and reaction time was reduced to 1 day. All the synthesized products were then characterized for their structure elucidations using different physical techniques like FTIR, CHN, TGA, 13CNMR & 29SiNMR in solid state, where Si¿O cages of all compounds were elaborated through 29Si-NMR in solid state as well as through their respective FTIR patterns, while the pendant chains anchored to the POSS cages were confirmed using 13C-NMR results along with their respective FTIR spectra. The synthesized compounds were then tested for their thermal stability using the TGA technique. After optimizing the synthesis of cubic silsesquioxanes, hybrids PAA-13-3, PAA-MTC and PAA-Ph were worked out for their abilities of capturing divalent cations like Cu2+, Cd2+ and Pb2+ from their aqueous solutions, where Cu2+ showed higher affinity of sorption than other two bivalent metals. These sorption systems were analyzed using the ICP-OES. To explain the sorption behaviour of these samples some statistical models like Langmuir, Freundlich, Sips, Temkin and Redlich-Peterson were applied to the sorption data, where the data for Cu2+ on to PAA-13-3 was best fitted by Langmuir adsorption isotherm model showing the sorption to be monolayer, while in case of PAA-MTC and PAA-Ph Freundlich model was found to be a best fit, confirming multilayer sorption. One of the synthesized materials (PAA-13-3) was also evaluated for its ability to adsorb gaseous CO2 and was proved to be promising in removing CO2, even at low pressures (max. 100 mmHg). The adsorption of CO2 in the material is also studied by solid-gas adsorption calorimetry through a calorimeter especially developed for this system, where enthalpy of adsorption values were found to be between -7 and -36 kJ mol-1
Doutorado
Quimica Inorganica
Doutor em Ciências
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Adhikari, Kamal. "Effects of functionalized single walled carbon nanotubes on the processing and mechanical properties of laminated composites." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99617.
Full textAbstract:
Carbon Nanotubes are thought to have tremendous potential as reinforcements for the next generation of composite materials. In the past decade, the enhancing effects of the nanotubes on the mechanical, electrical as well as multi-functional properties of polymer composites have been reported. However, the same nanotubes/polymer composites investigated by different research groups, in many cases, do not show a good agreement with one another. The root cause of this variability is believed to lie in the processing methodology employed to prepare the composites. Before one can propose an ideal and systematic processing condition, it is imperative to have a fundamental understanding of the effect of these nanotubes on the processing of the nanotube-based composites. In this study, the effect of 0.2wt.% functionalized single walled carbon nanotubes on the various thermo mechanical and thermo chemical properties of aerospace grade epoxy was investigated. Namely, the thermal degradation, rheological behavior, cure kinetics as well as the thermal expansion behavior of the epoxy were addressed. In addition, the effect of the application small quantity of nanotube/epoxy composite film on the interlaminar shear strength (ILSS) of a conventional laminated carbon fibre/epoxy prepregs was also investigated. The characterization results show that the presence of the nanotubes has a very significant effect on some of the inherent physical and chemical properties of the epoxy. The presence of these nanotubes leads to a delay in the degradation temperature of the epoxy. The viscosity sees a seven-fold increase at room temperature and the resin also gels at a lower temperature in the presence of the nanotubes. At the same time, the total heat of reaction is also lowered on addition of the nanotubes. The mechanical test, however, shows that the addition of the nanotube/epoxy film does not affect the ILSS of the laminated carbon fibre/epoxy composite. This ILSS value is also found to be dependant on the controlled alignment of the nanotubes and the method of application of the film at the interfaces of the laminates. Finally, it was observed that the nanotubes, when used in such low contents, also had no effect on the thermo mechanical properties of the epoxy.Les nanotubes de carbone sont considérés comme ayant un potentielénorme pour assurer le rôle de renforts dans la prochaine génération de matériauxcomposites. Dans les décennies précédentes, les effets des nanotubes surl'amélioration des propriétés mécaniques, électriques et multi-fonctionnelles despolymères ont été révélés. Par contre, dans la plupart des cas, les études réaliséespar différents groupes de recherche et portant sur les mêmes composites faits depolymère renforcé de nanotubes ne présentent pas toutes des résultatscomparables. La cause majeure de cette variabilité est la méthodologie utiliséelors du procédé de fabrication de ces composites. Avant que quiconque ne suggèreune méthodologie idéale et systématique, il est impératif de comprendre les basesfondamentales de l'effet des nanotubes sur le procédé de fabrication. Dans cetterecherche, les effets des nanotubes de carbone à paroi simple sur les propriétésthermo mécaniques et thermo chimiques d'une résine époxy de gradeaéronautique ont été investigués. Les caractéristiques étudiées comprennent ladégradation thermique, le comportement rhéologique, la cinétique depolymérisation, ainsi que l'expansion thermique. L'effet de l'application d'unfilm de nanotube/époxy sur la résistance interlaminaire au cisaillement aégalement été étudié avec un préimprégné conventionel de fibre de carbone etd'époxy. Les résultats de caractérisation montrent que les nanotubes ont un effetsignificatif sur certaines propriétés physiques et chimiques inhérentes à l'époxy.La présence des nanotubes crée un délai dans la température de dégradation del'époxy. La viscosité de la résine est 7 fois plus élevée à la température de la pièceet sa température de gélification est inférieure. De plus, la chaleur totale deréaction est diminuée. Par contre, les tests mécaniques montrent que l'applicationd'un film de nanotube/époxy ne cause pas de changement dans la résistanceinterlaminaire au cisaillement d'un préimprégné de fibre de carbone et d'époxy.Par ailleurs, cette valeur de résistance est dépendante de l'alignement desnanotubes et de la méthode d'application du film sur les interfaces du laminé.Finalement, il a été observé que les nanotubes n'ont aucun effet sur les propriétésthermo mécaniques.
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Ferreira, Rúben Rodrigues. "Flavylium-Functionalized Carbon Quantum Dots." Master's thesis, 2016. http://hdl.handle.net/10362/20621.
Full textAbstract:
The goal of this master thesis was the functionalization of carbon quantum dots (CQDs) with flavylium salts. CQDs were synthesized through the hydro-thermal method using citric acid as a carbon precursor and ethylenediamine as a basic catalyst and passivation agent. Since these CQDs are known to bear pri-mary amines groups at their surface, flavylium derivatives with tails containing carboxyl groups were synthesized, 7-hydroxy-4’-methylcarboxyflavylium and 7-hydroxy-4’-methylcarboxy-4-phenylflavylium, in order to functionalize the CQDs with these kind of molecules, using EDC as coupling agent.
CQDs were successfully functionalized with these two flavylium, however, the focus of this thesis was the study of CQDs functionalized with 7-hydroxy-4’-methylcarboxy-4-phenylflavylium, due to its simplest equilibrium between AH+ and A. CQDs were characterized by UV-Vis and steady-state fluorescence spec-troscopy.
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"Polyethyleneimine functionalized nano-carbons for the absorption of carbon dioxide." Thesis, 2012. http://hdl.handle.net/1911/70229.
Full textAbstract:
The evolution of nanotechnology over the past 20 years has allowed researchers to use a wide variety of techniques and instruments to synthesize and characterize new materials on the nano scale. Due to their size, these nano materials have a wide variety of interesting properties, including, high tensile strength, novel electronic and optical properties and high surface areas. In any absorption system, a high surface areas is desirable, making carbon nano materials ideal candidates for use in absorption systems. To that end, we have prepared a variety of nano carbons, single walled carbon nanotubes, multi walled carbon nanotubes, graphite intercalation compounds, graphite oxide, phenylalanine modified graphite and fullerenes, for the absorption of carbon dioxide. These nano carbons are functionalized with the polymer, polyethyleneimine, and fully characterized using Raman spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, solid state 13 C NMR, and thermogravimetric analysis. The carbon dioxide absorption potential of the PEI-nano carbons was evaluated using thermogravimetric analysis at standard room temperature and pressure. We have demonstrated the high gravimetric capacity of carbon dioxide capture on these materials with extremely high capacities for PEI-C 60 .