Dissertations / Theses on the topic 'Physisorbed'
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Griffiths, Paul Thomas. "Photodissociation of physisorbed molecules." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267768.
Full textPalmer, R. E. "Inelastic electron scattering by physisorbed molecules." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383837.
Full textPapadantonakis, Kimberly Marshall Okumura Mitchio Lewis Nathan Saul. "Exploration of physisorbed monolayers for molecular-scale surface patterning /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-07222008-144633.
Full textSrepusharawoot, Pornjuk. "Computational Studies of Hydrogen Storage Materials : Physisorbed and Chemisorbed Systems." Doctoral thesis, Uppsala universitet, Materialteori, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132875.
Full textFelaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 712
Guest, Richard James. "Spectroscopic studies of the structure and dynamics of physisorbed oxygen." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307039.
Full textKagan, Mark R. "Raman spectroscopy of organic molecules physisorbed onto graphitic carbon surfaces /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935958848054.
Full textGameson, I. "An X-ray study of gases on solids." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233976.
Full textPhillips, Tamsin Katie. "The influence of the carbonyl group in physisorbed monolayers on graphite." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609212.
Full textConner, Marilyn W. "Theory of solid physisorbed films within the Potts lattice gas model /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487266691096888.
Full textStocker, Matthias [Verfasser]. "Investigations of the role of physisorbed hydrogen in STM experiments / Matthias Stocker." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2015. http://d-nb.info/108056294X/34.
Full textFigueroa, Jhon J. "Immobilization and Characterization of Physisorbed Antibody Films Using Pneumatic Spray as Deposition Technique." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4889.
Full textBlock, Stephan [Verfasser]. "On surface forces and morphology of linear polyelectrolytes physisorbed onto oppositely charged surfaces / Stephan Block." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1010396889/34.
Full textMorton, Robert Simon. "The formation of positronium and its application to the study of two-dimensional physisorbed films." Thesis, Royal Holloway, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314166.
Full textKossler, Sarah [Verfasser], Peter A. [Akademischer Betreuer] Feulner, Wilfried [Akademischer Betreuer] Wurth, and Katharina [Akademischer Betreuer] Krischer. "Electronic properties of physisorbed helium / Sarah Kossler. Gutachter: Wilfried Wurth ; Katharina Krischer. Betreuer: Peter A. Feulner." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1019588926/34.
Full textBurns, Teresa Ellen. "Asymmetric Adsorbate and Substrate Interactions in Physisorbed Systems: N2 on Graphite and Dipolar Molecules on Ionic Substrates." DigitalCommons@USU, 1994. https://digitalcommons.usu.edu/etd/2090.
Full textMcGinty, Kathryn Mary. "Surface Modification of Poly(vinyl chloride) by Physisorbed Free Radical Initiation for Reduced Plasticizer Migration and Antimicrobial Properties." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226615844.
Full textMoine, Mohamed Moustapha. "Fonctionnalisation de surface d'une tôle de cuivre par greffage d'acides alkylphosphoniques auto-assemblés en vue d'améliorer ses propriétés en emboutissage." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2075.
Full textSheet metal forming processes are quickly evolving to meet new requirements of deep drawing such as: continuousminimization of dimensional tolerances intervals, cost efficiency at mass production, appearance of new materialstypes, environmental concern. The success of such operation is predominated by controlling friction at the contactbetween the metal sheet and forming tool in relative motion. In the present work, we propose to functionalize themetal sheet surface using grafting of self-assembled organic molecules by simple immersion in a solution containingthe reactive molecules. Consequently, thin film of alkylphosphonic acid (CnH2n+1PO(OH)2) was grafted on copperoxide substrate in order to establish a correlation between the physicochemical properties of the films andtribological behavior. Frictional response was studied by two experimental means of contact conditions (stripdrawing testing and ball-on-plane tribometer). The influence of three factors for the preparation of substrate wasconsidered. Firstly, the nature of its surface just before functionalization including the presence of an oxide orhydroxide layer was studied. Then, the ultrasonic surface cleaning after functionalization (removal physisorbedspecies) and finally, the alkyl chain length of the organophosphonic molecule (n = 4, 12 and 16). Although theformation of this functionalization is simple (made from a single molecule), the surface investigation techniques(PM- IRRAS , XPS, electrochemistry , SEM, .., etc.) show that self-assembled films consist of a bilayer with a goodgrafting quality and anticorrosion properties. The bilayer is composed of a first monolayer of molecules chemisorbedon the surface (or SAM) on which a second layer of physisorbed species is deposited. Furthermore, this study alsoshowed that the physisorbed species have a key role in the tribological behavior of self-assembled film (lower andstable friction coefficient and high resistance to galling)
Razafitianamaharavo, Angelina. "Étude structurale du film de cyclohexane physisorbé sur graphite : Étude thermodynamique et structurale du film mixte (krypton-cyclohexane) physisorbe sur graphite." Nancy 1, 1989. http://www.theses.fr/1989NAN10080.
Full textCafe, Peter F. "Towards reliable contacts of molecular electronic devices to gold electrodes." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3870.
Full textCafe, Peter F. "Towards reliable contacts of molecular electronic devices to gold electrodes." University of Sydney, 2008. http://hdl.handle.net/2123/3870.
Full textSYNOPSIS OF THIS THESIS The aim of this thesis is to more fully understand and explain the binding mechanism of organic molecules to the Au(111) surface and to explore the conduction of such molecules. It consists of five discreet chapters connected to each other by the central theme of “The Single Molecule Device: Conductance and Binding”. There is a deliberate concentration on azine linkers, in particular those with a 1,10-phenanthroline-type bidentate configuration at each end. This linker unit is called a “molecular alligator clip” and is investigated as an alternative to the thiol linker unit more commonly used. Chapter 1 places the work in the broad context of Molecular Electronics and establishes the need for this research. In Chapter 2 the multiple break-junction technique (using a Scanning Tunnelling Microscope or similar device) was used to investigate the conductance of various molecules with azine linkers. A major finding of those experiments is that solvent interactions are a key factor in the conductance signal of particular molecules. Some solvents interfere with the molecule’s interaction with and attachment to the gold electrodes. One indicator of the degree of this interference is the extent of the enhancement or otherwise of the gold quantized conduction peak at 1.0 G0. Below 1.0 G0 a broad range for which the molecule enhances conduction indicates that solvent interactions contribute to a variety of structures which could bridge the electrodes, each with their own specific conductance value. The use of histograms with a Log10 scale for conductance proved useful for observing broad range features. vi Another factor which affects the conductance signal is the geometric alignment of the molecule (or the molecule-solvent structure) to the gold electrode, and the molecular alignment is explored in Chapters 3 for 1,10-phenanthroline (PHEN) and Chapter 4 for thiols. In Chapter 3 STM images, electrochemistry, and Density Functional Theory (DFT) are used to determine 1,10-phenanthroline (PHEN) structures on the Au(111) surface. It is established that PHEN binds in two modes, a physisorbed state and a chemisorbed state. The chemisorbed state is more stable and involves the extraction of gold from the bulk to form adatom-PHEN entities which are highly mobile on the gold surface. Surface pitting is viewed as evidential of the formation of the adatom-molecule entities. DFT calculations in this chapter were performed by Ante Bilic and Jeffery Reimers. The conclusions to Chapter 3 implicate the adatom as a binding mode of thiols to gold and this is explored in Chapter 4 by a timely review of nascent research in the field. The adatom motif is identified as the major binding structure for thiol terminated molecules to gold, using the explanation of surface pitting in Chapter 3 as major evidence and substantiated by emergent literature, both experimental and theoretical. Furthermore, the effect of this binding mode on conductance is explored and structures relevant to the break-junction experiment of Chapter 2 are identified and their conductance values compared. Finally, as a result of researching extensive reports of molecular conductance values, and having attempted the same, a simple method for predicting the conductance of single molecules is presented based upon the tunneling conductance formula.
VENKATAPEN, VERONIQUE. "Simulation de melanges de gaz rares physisorbes sur graphite en monocouche." Paris 7, 1992. http://www.theses.fr/1992PA077205.
Full textMakoudi, Younes. "Etudes par microscopie STM de molécules organiques physisorbées sur semi-conducteurs." Phd thesis, Université de Franche-Comté, 2009. http://tel.archives-ouvertes.fr/tel-00463079.
Full textMakoudi, Younes. "Etude par microscope STM de molécules organiques physisorbées sur semi-conducteurs." Besançon, 2009. http://www.theses.fr/2009BESA2020.
Full textMy project dealt with achievement and study of isolated molecules on boron silicon surface (OD system), molecular self-alignment on samarium/silicon interface (1D system) and 2 dimensionnel molecular self-assembly on Si(111)-7x7 and Si(111)-B surfaces (2D system). In order to circumvent the problem of traditional silicon surface reactivity with TT-conjugated molecules, we use the Si(111 )-B surface. This surface has the unique particularity to exhibit depopulated dangling bonds due to the presence 01 boron atoms under the top silicon layer. Consequently, TT-conjugated organic molecules can interact weakly with the pz depopulated dangling orbitals of the surface. To achieve self-alignment of organic molecules, we used an innovative concept based on the template effect of the pre-structured semi- conductive SmSi(111) interface. This substrate was selected because Sm deposition in the submonolayer range leads to a 8x2- reconstruction, which is a well-defined one-dimensional semi-metallic structure. Adsorption of aromatic molecules [1,4- di-(9- ethynyltriptycenyl)-benzene] on SmSi(111)-8x2leads to a good self-alignment of molecules along the [1-10] direction and the molecules are parallel to the atomic rows of the 1 D SmSi(111)- 8x2 structure. To create 2 dimensionnel molecular self-assemblies on silicon surface at room temperature,we proposed two new strategies: The first uses the zwitterionic molecules [4-methoXy-4'-(3-sulfonatopropyl)- stilbazolium ] and Si(111)- 7x7 surface. The second technique is based on the choice of the molecule/substrate system. We chose SiB surface in order to reduce molecules/substrate interaction and a highly polar molecule (4-aminobenzonitrile) to promote molecule/molecule interactions
Bah, Abdellah. "Étude de films de chlorométhane et de trichlorométhane physisorbes sur les plans de base du graphite." Nancy 1, 1994. http://www.theses.fr/1994NAN10017.
Full textARANDA, PABLO. "Etude de la fusion bidimensionnelle par diffraction de rayons x : application a la monocouche de tetrachloromethane physisorbe sur graphite." Paris 6, 1994. http://www.theses.fr/1994PA066302.
Full textDubois, Mathieu. "Simulations de microscopie à effet tunnel : application à la surface (100) du silicium et aux molécules physisorbées." Lille 1, 2004. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2004/50376-2004-159.pdf.
Full textDans un premier temps, ce modèle sera mis en application à l'étude des différentes reconstructions de la surface (100) du silicium. Les résultats théoriques reproduisent relativement bien les données expérimentales obtenues à 5\,K et permettent de comprendre la dépendance en tensions des images et de conclure que la surface est toujours semi-conductrice à basse température. Ces résultats mettent également en avant l'importance des interactions pointe-surface. Dans un deuxième temps, le modèle est utilisé pour étudier une classe de molécules, les thiénylènevinylènes, physisorbées sur la surface (100) du silicium. Nous proposons alors l'origine suivante pour la contribution principale au courant tunnel: cette contribution ne proviendrait pas de la mise en résonance de l'état HOMO de la molécule avec le niveau de Fermi de la pointe mais plutôt de l'abaissement, par la présence de la molécule, de la barrière tunnel entre la pointe et la surface, faisant ainsi ressortir, là où elle repose, les caractéristiques du silicium
Hamdi, Alaoui Moulay Ahmed. "Étude thermodynamique et structurale des phases bidimensionnelles à plus d'un constituant physisorbées sur graphite : cas du film mixte krypton-méthane." Nancy 1, 1994. http://www.theses.fr/1994NAN10045.
Full textAbdelmoula, Mustapha. "Etude thermodynamique et structurale du film pur de tétrachlorure de carbone et des films mixtes (krypton-tétrachlorure de carbone) et (méthane-tétrachlorure de carbone) physisorbés sur graphite." Nancy 1, 1991. http://docnum.univ-lorraine.fr/public/SCD_T_1991_0022_ABDELMOULA.pdf.
Full textAngerand, François. "Étude thermodynamique et structurale des changements de phase bidimensionnels dans des films de molécules physisorbées sur le graphite : Rôle de l'ordre orientationnel dans les phénomènes de mouillage et de transition rugueuse." Nancy 1, 1987. http://www.theses.fr/1987NAN10268.
Full textSer, Frédéric. "Etude thermodynamique et structurale des changements de phase bidimensionnels dans des films de chlorure d'hydrogène et de quelques autres physisorbés sur la face de base du graphite : application au mouillage et à la transition rugueuse /." Saclay : Commissariat à l'énergie atomique, 1991. http://catalogue.bnf.fr/ark:/12148/cb35415552s.
Full textSer, Frédéric. "Etude thermodynamique et structurale des changements de phase bidimensionnels dans des films de chlorure d'hydrogene et de quelques autres molecules physisorbees sur la face de base du graphite. Application au mouillage et a la transition rugueuse." Paris 11, 1990. http://www.theses.fr/1990PA112301.
Full textStocker, Pierre. "Ordre et désordre de couches minces: A/ préfusion de surface de films minces de méthane physisorbés sur graphite, étudiée par diffusion de neutrons: B / épitaxie de disiliciure de fer er de cobalt Si(111) : étudiée par diffusion de rayons X." Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22056.
Full textUrban, Nathan Mark. "Thermodynamics and structure of fluids physisorbed on nanotubes." 2006. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1354/index.html.
Full textPapadantonakis, Kimberly Marshall. "Exploration of Physisorbed Monolayers for Molecular-Scale Surface Patterning." Thesis, 2009. https://thesis.library.caltech.edu/2966/4/Chapter_4_Towards_Surface_Patterning_Using_Physisorbed_Monolayers_as_Masks.pdf.
Full textMany simple organic molecules, such as straight-chain alkanes and simple aromatics, spontaneously assemble into highly ordered monolayers at solid–liquid interfaces. These monolayers are composed of molecules that lie flat at the interface without forming chemical bonds to the surface of the solid. These monolayer structures are highly ordered and produce patterns with features on the scale of just a single nanometer in length. The exploitation of this physisorption phenomenon may provide a promising route toward an inexpensive nanometer-scale surface patterning technique. However, two fundamental challenges must be overcome before physisorbed monolayers can be useful in surface-patterning applications: (1) absence of control over the particular pattern formed by the molecules; and (2) pattern impermanence.
This document opens with an introductory chapter that contains background on physisorbed monolayers and a brief description of scanning tunneling microscopy, the experimental technique which is commonly used to study monolayers. The second and third chapters present details on the results of experiments with a monolayer templating technique. This templating technique involves replacement of the molecules comprising a monolayer of either normal alkanes or symmetrical thioethers by symmetrical ethers. The ethers are forced to conform to the structure of the existing template monolayer, which differs from the structure of an ether monolayer formed in the absence of the template. The monolayer templating technique offers researchers a limited method for exercising control over the surface patterns formed by particular molecules.
The challenge of pattern impermanence is addressed in the fourth chapter of this document. The molecules comprising physisorbed monolayers are free to exchange with molecules in the solution contacting the surface, thus the orientation of the monolayer structure within a particular surface region can change with time. A technique analogous to traditional lithographic methods that may allow physisorbed monolayers to be used for permanent surface patterning is described. The technique would employ physisorbed monolayers as surface masks while other molecular species chemically bond to regions of the surface left uncovered by the masking monolayer. Descriptions of the progress made toward the development of the patterning technique, and of the substantial challenges encountered during efforts to develop such a patterning method close the chapter.
Miller, Brendan Paul. "Diffusion of physisorbed layers and their connection to MEMS effectiveness." 2009. http://www.lib.ncsu.edu/theses/available/etd-07212009-145828/unrestricted/etd.pdf.
Full textBoutchko, Rostyslav Dmytrovych. "Coupled dynamics of inert of intert gases physisorbed on crystal surfaces." 2001. http://www.library.wisc.edu/databases/connect/dissertations.html.
Full textSiegel, Amanda P. "Regulating Lipid Organization and Investigating Membrane Protein Properties in Physisorbed Polymer-tethered Membranes." 2012. http://hdl.handle.net/1805/2890.
Full textCell membranes have remarkable properties both at the microscopic level and the molecular level. The current research describes the use of physisorbed polymer-grafted lipids in model membranes to investigate some of these properties on both of these length scales. On the microscopic scale, plasma membranes can be thought of as heterogenous thin films. Cell membranes adhered to elastic substrates are capable of sensing substrate/film mismatches and modulating their membrane stiffness to more closely match the substrate. Membrane/substrate mismatch can be modeled by constructing lipopolymer-enriched lipid monolayers with different bending stiffnesses and physisorbing them to rigid substrates which causes buckling. This report describes the use of atomic force microscopy and epimicroscopy to characterize these buckled structures and to illustrate the use of the buckled structures as diffusion barriers in lipid bilayers. In addition, a series of monolayers with varying bending stiffnesses and thicknesses are constructed on rigid substrates to analyze changes in buckling patterns and relate the experimental results to thin film buckling theory. On the molecular scale, plasma membranes can also be thought of as heterogeneous mixtures of lipids where the specific lipid environment is a crucial factor affecting membrane protein function. Unfortunately, heterogeneities involving cholesterol, labeled lipid rafts, are small and transient in live cells. To address this difficulty, the present work describes a model platform based on polymer-supported lipid bilayers containing stable raft-mimicking domains into which transmembrane proteins are incorporated (αvβ3, and α5β1integrins). This flexible platform enables the use of confocal fluorescence fluctuation spectroscopy to quantitatively probe the effect of cholesterol concentrations and the binding of native ligands (vitronectin and fibronectin for αvβ3, and α5β1) on protein oligomerization state and on domain-specific protein sequestration. In particular, the report shows significant ligand-induced integrin sequestration with a low level of dimerization. Cholesterol concentration increases rate of dimerization, but only moderately. Ligand addition does not affect rate of dimerization in either system. The combined results strongly suggest that ligands induce changes to integrin conformation and/or dynamics without inducing changes in integrin oligomerization state, and in fact these ligand-induce conformational changes impact protein-lipid interactions.
Patil, Kalyan G. "Understanding Structure And Growth Of Physisorbed Films : A Combined Atomic Force Microscopy And Modeling Study." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2402.
Full textYeh, Chia-Wen, and 葉珈妏. "Application of Anion-Physisorbed Multi-walled Carbon Nanotubes on Photoelectrode for Dye-sensitized Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/35980155034475900674.
Full text國立臺灣大學
高分子科學與工程學研究所
100
In this thesis, multi-walled carbon nanotubes(MWCNTs) physisorbing anionic and nonionic dispersing agent for surface modification were dispersed in TiO2 thin film utilizing as a photoelectrode for dye-sensitized solar cells (DSSCs). Anionic dispersing agents such as sodium dodecylbenzenesulfonate(SDBS) and poly (sodium4-styrenesulfonate) (NaPSS) with molecular weight of 9350, 20800 and 70000 were used to disperse MWCNTs. We also chose amphiphilic triblocks of PEG-PPG-PEG as nonionic surface modifying agents, such as P123、F68、and F108. The procedure for surface treatment MWCNTs is as following. Surface modifying agents and MWCNTs were dispersed and adsorbed in water by sonication. After fully adsorption, the solution was filtrated to remove the extra dispersing agents. After drying, the surface-modified MWCNTs were obtained. From the results of UV-vis spectroscopy, zeta potential and dynamic light scattering measurements, anionic surface modifying agents have better dispersing power than nonionic surface modifying agents because anionic agents have benzene ring to physisorb onto CNTs via π-π stacking. Furthermore, the electrostatic repulsion from the SO3- groups leads to the charge stabilization of MWCNTs compared to the nonionic agents. Then we dispersed anion-physisorbed MWCNTs onto the TiO2 system. From the XRD results, we found that TiO2 can crystallize into more anatase structures in the presence of MWCNTs. The resulting materials also had higher light transmittance. For the performance of DSSCs with MWCNT-TiO2 photoelectrode, the addition of 0.03wt% CNT to the TiO2 film could enhance the Jsc of DSSC from 18.65mA/cm2 to 19.26 mA/cm2. And the increase of Jsc resulted in higher power conversion efficiency and better charge collection efficiency because of good conductivity of MWCNTs, more anatase TiO2 crystal structures and higher light transmittance of the MWCNT-TiO2 films. The best Jsc and power conversion efficiency of 20.68mA/cm2 and 8.42% were achieved with MWCNT(70000) dispersing in TiO2. In addition, in order to enhance the light harvesting efficiency, the larger size of TiO2 scattering layer was deposited on the outer layer of MWCNT-TiO2 thin films. After addition of the scattering layer, the Jsc and power conversion efficiency were both increased to 21.44mA/cm2 and 8.84%.
Chang, Yu-Hsun, and 張育勳. "The investigation on the dispersion of ionic liquids-physisorbed MWCNT and the applications of MWCNT/epoxy nanocomposites." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/10559186537794114300.
Full text國立臺灣大學
高分子科學與工程學研究所
102
The aim of this thesis was to discuss the dispersion of multi-walled carbon nanotube (MWCNT) modified by physical adsorption with ionic liquids. We investigated the cation-πinteraction between MWCNT and cation structure of ionic liquid. Pristine MWCNT and modified MWCNT would be incorporated individually into diglycidyl ether of bispheol-A (DGEBA) resin to fabricate epoxy/MWCNT suspension. We studied the processing and rheological behavior of epoxy/MWCNT suspensions, then the suspension was cured to form thin films or bulk nanocomposite. We also studied the electrical properties of nanocomposite films and the shear strength of bulk composite with the controlled applied normal stress. The thesis divided into four parts. In the first part, we synthesized three types of ionic liquids, 1-(2-acryloyloxy-ethyl)-3-methyl benzoimidazol-1-ium iodide (AMBImI), 10-Methyl-acridinium iodide(MAcI) and 1,3-dimethyl-3H-benzotriazolium iodide(DMBTAzI), to physisorb onto MWCNT and obtained MWCNT-AMBImI, MWCNT-MAcI and MWCNT-DMBTAzI. We also used pre-ionized compounds physisorbed onto MWCNT to compare with ionic liquid-physisorbed MWCNT. Then, we investigated the effect of physisorption by cation-π interaction. We observed the excess adsorption with ionic liquid by thermo gravimetric analysis (TGA), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). Ionic liquid-physisorbed MWCNT also showed well dispersion in organic solvent and nanocomposite observed by TEM. Consequently, the glass transition temperature of nanocomposites contained modified MWCNT was enhanced to 129℃ due to the well interaction between MWCNT and epoxy resin. In the second part, we investigated the rheological behavior of epoxy/MWCNT suspension. MWCNT concentration effect on rheology was investigated in order to understand the processing and rheological properties of MWCNT composites. It was well known that storage modulus G’ and loss modulus G” of rheology were related to the degree of phase shift, δ, such that δ = tan-1(G” / G’). As the phase shift was higher than 45 degree, the G” was higher than G’ belonged to fluid behavior. On the contrary, as the phase shift was lower than 45 degree, it belonged to solid-like behavior. The suspension containing modified MWCNT gelled earlier than that containing pristine MWCNT because modified MWCNT had better dispersion to form network structure. We observed the plateau in storage modulus at lower angular frequency. The viscosity increased as the content of MWCNT was increased. We estimated volume fraction of particle domain aggregated by MWCNT through Thomas-modified Einstein viscosity equation and utilized small angle x-ray spectrum (SAXS) to measure the change of aggregated network structure. Besides, we also investigated rheological behavior of the epoxy/MWCNT suspension at various temperatures. At certain content of MWCNT, the suspensions showed more solid-like behavior as the temperature was increased. Increasing temperature facilitated the gelation of the suspension. The volume fraction of particle domain aggregated by MWCNT was changed by temperature effect. In the third part, we investigated electrical properties of epoxy/MWCNT nanocomposite for modified MWCNT. We observed AC volume conductivity displayed a plateau at low frequency region until the critical frequency (ωc) for the nanocomposite containing 0.4 wt% pristine MWCNT. Above critical frequency (ωc), AC volume conductivity also was increased with frequency. ωc shifted to higher frequency with the increasing of MWCNT contents. We utilized universal dynamic response (UDR) to fit AC volume conductivity of nanocomposite and got s value was about 0.7-1. The value also shifted to higher frequency due to nanocomposites containing well dispersion modified MWCNT. By incorporation of 2 wt% pristine MWCNT, the volume conductivity of nanocomposite enhanced from 10-11(S/cm) of insulator to 1.25×10-5(S/cm). Moreover, the highest volume conductivity was improved to 4.56×10-5(S/cm) as the nanocomposite containing 2 wt% MWCNT-MAcI or MWCNT-DMBTAzI. DC volume conductivity also obeyed percolation theory σDC=σ0 (p-pc)t. For modified MWCNT, it showed higher index of t and σ0 constant, and pc was below 0.3 wt%. The lowest pc of modified MWCNT was 0.18wt%. In the last part of thesis, we measured the shear strength of bulk nanocomposite with controlled applied normal stress. The shear strength of cured DGEBA epoxy resin was 83.5 MPa. The shear strength of nanocomposite with 1 wt% MWCNT-MAcI or MWCNT-DMBTAzI was improved to 98.69MPa and 95.49MPa due to the excellently mechanical properties of MWCNT. In surface morphology, cross section of shear fracture of DGEBA epoxy resin dramatically changed from vein-like structure to rough chip-like structure as the inclined angle and compressive area was increased. With the incorporation of modified MWCNT-MAcI or MWCNT-DMBTAzI, the morphology of fracture clearly showed more branches in vein-like structure because of the improvement of MWCNT dispersion. As the inclined angle was increased to 60°, we could observe the fracture of nanocomposite containing modified MWCNT was damaged obviously due to the better dispersion. Finally, cation-π interaction between ionic liquid and MWCNT was investigated that could improve the dispersion of MWCNT. It was not necessary to modify MWCNT through many complex processes. The nanocomposites we prepared also had excellent properties and had graet potential for application in the future.
Sallabi, Abdulwahab K. "Computer simulations of the structure, stability and phase transitions of diatomic molecules physisorbed on ionic surfaces : the CO/MgO(001), N2/MgO(001) and N2/NaCl(001) systems." Thesis, 2002. http://spectrum.library.concordia.ca/1715/1/NQ68200.pdf.
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