Дисертації з теми "Polymer Nano-films"
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Wang, Xiaoteng. "Directed Nano-Patterning of Polymer Nanocomposite Thin Films." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462141968.
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Akram, Aisha. "Nano indentation of particulate and polymer films." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249316.
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Hung, Ming-Tsung. "Heat transport in polymer thin films for micro/nano-manufacturing." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1459914931&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Samadi, Azadeh. "Synthesis and analysis of nano-thin polymer films for separation applications." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1247508734/.
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Jin, Weize. "Relative Alignment of CZA (Cold Zone Anneal) Polymer In Nano Imprinted Films." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430229845.
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Qian, Jiajie. "Control Of C60-POSS Nano Particle Locaiton In DirectedSelf-Assembly of Block Copolymer Thin Films." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398074026.
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Zhao, Wei. "Flexible Transparent Electrically Conductive Polymer Films for Future Electronics." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1297888558.
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Bodnár, Eszter. "Electrospraying of polymer solutions for the generation of micro-particles, nano-structures, and granular films." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/379820.
Повний текст джерелаАнотація:
S'ha realitzat un estudi sobre els mecanismes de formació de micropartícules polimèriques i les seves pel•lícules granulars, a partir de l'assecat de microgotes de electrosprays. L'estudi se centra en diferents solucions de tres polímers insolubles en aigua: polimetil(metacrilat), poliestirè, i etil cel•lulosa. L'assecat d'aquests electrosprays dóna lloc a diverses morfologies de partícula, que han estat determinades mitjançant microscòpia d'escombrat electrònic, i han estat caracteritzades en funció del solvent, concentració del polímer, el seu pes molecular, i la humitat relativa ambient. Les morfologies obtingudes inclouen una varietat d'estructures de partícula globulars i filamentoses, que, a humitat relativa elevada, poden desenvolupar porositat. Aquestes característiques morfològiques han estat explicades mitjançant models qualitatius que involucren fenòmens fluid dinàmics i sobre separació de fases, presents en sistemes relacionats amb els estudiats. Un dels fenòmens fluid dinàmics involucrats clau són les inestabilitats coulòmbiques de gotes elèctricament carregades. A més, la interacció de no solvent de l'aigua en la precipitació del polímer pot donar lloc a textures poroses sobre la superfície de les partícules. Les diferents formes de textura han estat explicades en referència als fenòmens de breath figure formation (BFF), i a la inversió de fases induïda per vapor (vapor induced phase separation, o VIPS). També hem estudiat el creixement de les pel•lícules granulars formades a partir de les partícules polimèriques. Demostrem que la càrrega elèctrica transportada per les partícules cap a la pel•lícula influeix fortament en la dinàmica de creixement d’aquesta. Un millor coneixement dels mecanismes estudiats en aquesta tesi hauria de permetre dissenyar nous processos de manufactura de partícules i recobriments basats en electrospray.
Se ha realizado un estudio sobre los mecanismos de formación de micropartículas poliméricas y sus películas granulares, a partir del secado de microgotas de electropras. El estudio se centra en diferentes soluciones de tres polímeros insolubles en agua: polimetil(metacrilato), poliestireno, y etil celulosa. El secado de estos electrosprays da lugar a diversas morfologías de partícula, que han sido determinadas mediante microscopía de barrido electrónico, y han sido carSe ha realizado un estudio sobre los mecanismos de formación de micropartículas poliméricas y sus películas granulares, a partir del secado de microgotas de electropras. El estudio se centra en diferentes soluciones de tres polímeros insolubles en agua: polimetil(metacrilato), poliestireno, y etil celulosa. El secado de estos electrosprays da lugar a diversas morfologías de partícula, que han sido determinadas mediante microscopía de barrido electrónico, y han sido caracterizadas en función del solvente, concentración del polímero, su peso molecular, y la humedad relativa ambiente. Las morfologías obtenidas incluyen una variedad de estructuras de partícula globulares y filamentosas, que, a humedad relativa elevada, pueden desarrollar porosidad. Estas características morfológicas han sido explicadas mediante modelos cualitativos que involucran fenómenos fluido dinámicos y sobre separación de fases, presentes en sistemas relacionados con los estudiados. Uno de los fenómenos fluido dinámicos involucrados clave son las inestabilidades coulómbicas de gotas eléctricamente cargadas. Además, la interacción de no solvente del agua en la precipitación del polímero puede dar lugar a texturas porosas sobre la superficie de las partículas. Los diferentes tipos de texturas han sido explicadas en referencia a los fenómenos de breath figure formation (BFF), y a inversión de fases inducida por vapor (vapor induced phase separation, o VIPS). También hemos estudiado el crecimiento de las películas granulares formadas a partir de las partículas poliméricas. Demostramos que la carga eléctrica transportada por las partículas hacia la película influye fuertemente en la dinámica de crecimiento de ésta. Un mejor conocimiento de los mecanismos estudiados en esta tesis debería permitir diseñar nuevos procesos de manufactura de partículas y recubrimientos basados en electrospray.
A study has been made of the mechanisms underlying the formation of polymeric microparticles and of their granular films, by drying of electrospray microdroplets. The study is focused on different solutions of three water-insoluble polymers: polymethyl(methacrylate), polystyrene, and ethyl cellulose. The drying of such electrosprays result in diverse particle morphologies, which have been determined by scanning electron microscopy, and have been characterized as a function of the solvent, polymer concentration, polymer molecular weight, and ambient relative humidity. The morphologies obtained include a variety of globular and filamented particle structures, which, at elevated relative humidity, can develop porosity. These morphological features have been explained using qualitative models involving fluid dynamic and phase separation phenomena which are known to occur in closely related systems. One of the key fluid dynamic phenomena involved is the coulombic instability of electrically charged droplets. In addition, the non-solvent interaction of water on the precipitation of the polymer can lead to porous textures on the particles surfaces. The different kinds of textures have been explained by reference to breath-figure formation (BFF) and vapor induced phase separation (VIPS) phenomena. We have also studied the growth of the granular films of such polymer particles. We show that the electrical charge transported by the particles to the film have a strong influence on the film growth dynamics. The better understanding of the mechanisms studied in this thesis, should help design new manufacturing processes of particles and coatings based on electrospray.
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Mabuchi, Michiaki. "Nano-Structure and Thermal Relaxation of Ultrathin Polymer Films Prepared by the Langmuir-Blodgett Technique." Kyoto University, 1998. http://hdl.handle.net/2433/182337.
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Masclaux, Céline. "Etude de la structuration spontanée de films polymères en nano-impression thermique." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT034/document.
Повний текст джерелаАнотація:
La lithographie de nano-impression par déstabilisation spontanée de polymère est unevariante de la technique de nano-impression thermique, et permet de limiter le contact directentre moule et polymère. Le but de cette thèse est d’étudier cette déstabilisation spontanée etde déterminer si elle peut conduire à la formation de nanostructures en dupliquant de façonpositive un moule nano-structuré. Ce procédé est influencé, en particulier, par la température,le champ électrique externe ou interne au niveau des interfaces moule – air – polymère, ainsique par la distance d séparant les structures du moule et la surface du polymère.Les études réalisées au cours de cette thèse se sont concentrées sur l’influence de cesdifférents paramètres. Nous avons montré que la formation de motifs dépend plus de l’effetde charges que de la température, dans la mesure où le polymère peut néanmoins fluer. Nousavons surtout mis en évidence le scénario de structuration suivant : une duplication positiveapparaît dans un premier temps, et est suivie, dans certains cas, d’un remplissage des cavitésdu moule conduisant à une duplication négative. Un modèle théorique a été utilisé pourcalculer la longueur d’onde de déstabilisation la plus favorable, et une comparaison avec nosrésultats expérimentaux a permis d’expliquer pourquoi et dans quels cas la structurationfinale est positive ou négative. Une investigation a été accomplie sur la déstabilisationspontanée de substrats souples, mais la grande épaisseur des films conduit à unedéstabilisation de grande longueur d’onde, et donc à un remplissage complet du mouleNanoImprint lithography by spontaneous polymer destabilization is an alternative toThermal NanoImprint, which limits physical contact between polymer and mold surfaces.The purpose of this thesis is to investigate this spontaneous destabilization and to work out ifit can lead to the formation of nanostructures by duplicating positively a structured mold.This process is in particular affected by temperature or electric field present at mold - air -polymer interfaces and by the distance d between the structures of the mold and the polymersurface.The studies of this thesis were focused on the influence of these process parameters. Itwas shown that the structuration depends more of charges’ effect than temperature, since thepolymer can creep. We highlighted the following scenario of structuration: a positiveduplication appears first and is followed, in some cases, by the filling of the mold cavitiesleading to a negative duplication. A theoretical model was used to calculate the mostfavorable destabilization wavelength, and a comparison with experimental results helped toexplain why and under which circumstances the final structuration is positive or negative. Aninvestigation was performed on the spontaneous destabilization of flexible substrate but thebigger thickness of flexible films led to a destabilisation with a wide wavelength and so tothe filling of molds’ cavities
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Durret, Jérôme. "Développement de procédés de nanostructuration sur films de polymères flexibles." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT054/document.
Повний текст джерелаАнотація:
Les nanotechnologies représentent un potentiel de développements et d’applications considérables dans le domaine des matériaux ouvrant la voie à d’innombrables développements pour l’énergie, le transport, la santé, l’industrie, etc. Le biomimétisme a ainsi trouvé un nouveau moteur d'étude et de développement. La feuille de lotus est capable de faire perler l’eau avec une efficacité remarquable transformant n’importe quelle goutte d’eau en une bille répondant aux lois de la physique des solides. Cette propriété extraordinaire est due à l’association d’une composition chimique intrinsèquement hydrophobe avec une texturation hiérarchique de sa surface.Cette thèse s’intéresse à la compréhension des principes physiques qui régissent l'interaction des gouttes d'eau avec les surfaces de films polymères structurées de FEP, PMMA et PET. Deux technologies ont été mises en oeuvre pour la fabrication de surfaces superhydrophobes hiérarchiques : la nanoimpression (NIL) thermique et la gravure plasma. Nous avons mesuré les angles de contact et hystérésis de ces surfaces structurées afin d’identifier leur état de mouillage de Wenzel ou de Cassie-Baxter. Nous avons attaché une importance particulière au développement de solutions de fabrication et de caractérisations sur de grandes surfaces.Les propriétés antigivre ont été caractérisées, ainsi le rôle de la condensation dans la propagation du givre a été corrélé à la structuration de surface. De plus, nous avons mis en évidence le rôle du potentiel électrostatique de surface sur les retards de gel. Enfin, au vue du potentiel applicatif de ces surfaces, nous avons ajouté une dimension dynamique à l’étude en considérant les vitesses d’impact des gouttes. Un modèle de prédiction de la littérature a été comparé avec succès aux résultats expérimentauxNanotechnologies represent a considerable potential of development and application in the field of material science opening the way to innumerable developments for energy, transport, health, industry, and so on. Thus, biomimicry found a new driving force for study and development. The lotus leaf is able to repulse water with a remarkable efficiency transforming any drop of water into a ball following the laws of solid physics. This extraordinary property is due to the association of a hydrophobic chemical composition with a hierarchical texturing of its surface.This thesis focuses on the understanding of the physical principles governing the interaction of water drops on the surfaces of structured polymer films of FEP, PMMA and PET. Two technologies have been implemented for the production of hierarchical superhydrophobic surfaces: thermal nanoimprint lithography (NIL) and plasma etching. We have measured the contact angles and hysteresis of these structured surfaces in order to identify their Wenzel or Cassie-Baxter wetting state. We have attached particular importance to the development of manufacturing and characterization solutions on large surfaces.The anti-icing properties have been characterized and the role of condensation in the propagation of frost has been correlated with the surface texturing. In addition, we have highlighted the role of the electrostatic surface potential on frost delays. Finally, in view of the applicative potential of these surfaces, we added a dynamic dimension in the study considering the velocity of drops impact. A model of prediction from the literature was successfully compared to our experimental results
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Zhang, Fajian. "Electro-optic Properties of Semiconductor Nano-crystals And Electro-optic Polymers And Their Applications." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29289.
Повний текст джерелаАнотація:
In recent years, electro-optic polymers have been used to make various optical devices in the telecommunication field due to several advantages, such as large and fast electro-optic (EO) response. Semiconductor nano-crystals promise even higher response speed due to the unique quantum confinement mechanism, and they also show very high EO response because of surface and quantum size effects.
Many investigative efforts have been made in the area of semiconductor nano-clusters. These efforts mainly focus on synthesizing high quality particles, and their physical and chemistry properties (luminescence spectra, nonlinear optical, and other effects), but their electro-optic properties and potential uses in devices have not been fully investigated, so there is still much work to do in this aspect. For application of electro-optic polymers in electro-optic devices, the challenges are to develop more stable electro-optic polymers with higher electro-optic coefficients.
The electrostatic self-assembly (ESA) technique has many advantages over traditional polymer electro-optic film synthesis processes, such as spin coating. For ESA-generated EO films, no poling field is needed, high orientation of the EO polymer can be obtained which does not degrade with time, so the films can be very stable, and this processing is easily compatible with semiconductor VLSI technology. This is a very attractive technique.
The goal of this research is to develop new electro-optic materials by means of ESA techniques and to use them to form improved performance next generation electro-optic devices, with emphasis on two kinds of electro-optic materials: nano-sized II-VI semiconductors (CdS, CdSe), and electro-optic active polymers (chromophores), and their potential use in electro-optic devices.
In this research work, II-VI semiconductor nano-clusters have been synthesized, with particle diameters ranging from 4 nm to several tens of nanometers. There is a difference in peak positions of absorption and photo luminescence spectra, related to defects in nano-crystals. Larger CdS particles have larger differences than small CdSe particles. Particle sizes measured by absorption spectrum and by HRTEM methods are very close. Based on quantum mechanical theory, peak spectral shifts as a function of particle size can be predicted, but the theoretical results are typically far from the experimental results, because many complicating factors should be considered. Films fabricated by ESA have much stronger absorption than spin coated films, and exhibit a slight blue shift in peak position wavelength. Photo luminescence spectra also show a blue shift for ESA films with respect to spun films.
Polymeric electro-optic films were also fabricated by the ESA technique. Effects due to applying an external electrical field during the ESA process on film growth and properties have also been investigated. Peak position, optical density and wavelength at maximum absorption, all increase with the number of bilayers, and films made under external fields have lower absorption and peak wavelength than those of films fabricated without an external field. These results are related to the order parameter, and indicate that molecule alignment can be improved by the application of an external field during the process of ESA film growth.
CdSe nano-clusters have a much higher electro-optic coefficient than their bulk crystal counterparts. In comparison with polymers, they have totally different origins in their electro-optic effects. For both nano-cluster-and chromophore based ESA films, electro-optic coefficients are hi gher than those of spin-coated films, and no poling voltage is needed. The reasons have been fully discussed. This result means that the ESA technique is effective to align and hold the dipoles in films and to intensify the electro-optic effect.
CdSe quantum dots need 17. 5 ms to complete their physical orientation due to a rotation of the permanent dipole moment. Therefore, at lower frequencies (<100Hz), electro-optic modulation mainly stems from the orientation of the permanent dipole moment. At frequencies higher than 100 Hz, the electro-optic modulation mainly arises from the induced dipole moment orientation and pure electron movement.
The ratio of the electro-optic coefficients r333/r113 > 3. This means that ESA films cannot be treated as an ideal isotropic system with the C v symmetry, and interactions should be considered. Quadratic Kerr electro-optic coefficients have a similar frequency dependence to that of the linear electro-optic coefficients r333 and r113. This indicates that the orientational distribution of the CdSe quantum dots particularly contributes to the quadratic electro-optic modulation.
From the FT-IR measurement of the films, proton irradiation can break the N=N double bonding in pi-conjugated bridges, leading to damage of the conjugating structure, so causing a decrease of the EO coefficient. But the thermal and temporal stability of ESA films are much better than those of spin coated films; this is a significant feature of ESA technique.
The effect of an external field and film thickness on the optical and electro-optic properties of ESA films has been investigated. Electro-optic coefficient decreases with thickness. Electrical field influences the electronic states of the chromophores.
Based on the properties of electro-optic films, the applications of polymer and nano-cluster electro-optic films are discussed. A nano-cluster CdSe electro-optic film has a higher refractive index than the PS-119 polymer film, and these values they are much lower than that of semiconductor wafers, but slightly higher than optical silica glasses. Accordingly optical silica glasses are the ideal substrates for those films. By analysis, the cutoff thickness was determined, which defines the minimum film thickness required for light propagation. For channel waveguides, the aspect ratio w/t, w, and t are determined versus the refractive index of the electro-optic films. Modulator beam length and modulation index were discussed, for high speed operation. Modulator beam length should be carefully chosen to obtain high modulation index; similarly important is the refractive index match between core, substrate, and cladding layers. For high speed operation, traveling wave electrode designs were considered, based on effective refractive index and impedance matching. The effective dielectric constant and characteristic impedance as a function of electrode configuration (sizes) were diagramed, and this served as a basic design suggestion for traveling wave electrodes.Ph. D.
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Beck, Catherine Keel. "Characterization of Spin Coated Polymers in Nano-environments as a Function of Film Thickness." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34548.
Повний текст джерелаАнотація:
Polymer applications have become more demanding as industry continuously
turns to more microscopic parts. Due to the interactions of the polymer chains with the
supporting surface and the air interface, the thinner films required for such applications
have distinctly different properties than those of the well-defined bulk systems. The goal
of the current research is to elucidate the behavior of ultrathin films. Two separate
studies were performed on thin films supported on silicon wafer substrates: the first
focuses on the viscoelastic cooperativity of thin films, and the second concentrates on the
morphological behavior of polymer brush films.
For the first study, polymethyl methacrylate films were spin coated onto silicon
wafers, and the film thickness was determined using ellipsometry. A series of thin films
were examined using techniques such as dielectric analysis and thermal mechanical
analysis. The theory of cooperativity, which explains polymeric behavior using the
intermolecular and intramolecular forces among polymer chains, was employed to
understand the behavior of these thin films.
Another type of thin film, a polymer brush, was investigated in the second study.
Polymer brushes are formed by chemically bonding one end of many polymer chains to a
substrate. The other ends of the chains can interact with the surrounding environment
creating a brush-like structure. Constraining one end of a polymer chain alters the
behavior of such a thin film. Polymer brushes of the di-block copolymer poly(t-butyl
methacrylate) and polystyrene were produced on silicon wafers using spin coating
techniques. The effects of both grafting density and solvent washes were analyzed using
contact angle analysis and atomic force microscopy. In addition, hydrolysis was
successfully performed on existing polymer brush samples to produce polymer brushes of
the di-block copolymer polymethyl acrylic acid and polystyrene.Master of Science
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Woods, Courtney G. "Role of nano-particles on crystalline orientation in polypropylene/clay nanocomposite films." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180242/unrestricted/woods%5Fcourtney%5Fg%5F200312%5Fms.pdf.
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Lin, Yijian. "Structure-Property Relationship of Polyolefins Used as Packages and Adhesives." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1290044976.
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Su, Xingfang. "Degradable polymeric nano-films and particles as delivery platforms for vaccines and immunotherapeutics." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79555.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-131).
Degradable polymeric materials provide opportunities for the development of improved vaccines and immunotherapies by acting as platforms that facilitate the delivery of molecules to appropriate tissue and cellular locations to achieve therapeutic outcomes. To this end, we have designed and characterized nano-films and particles employing a hydrolytically degradable polymer for the delivery of vaccine antigens and immunotherapeutics. We first describe protein- and oligonucleotide-loaded layer-by-layer (LbL)-assembled multilayer thin films constructed based on electrostatic interactions between a cationic poly(p-amino ester) (PBAE, denoted Poly-1) with a model protein antigen, ovalbumin (OVA), and/or immunostimulatory CpG oligonucleotides for transcutaneous delivery. Linear growth of nanoscale Poly-1/OVA bilayers was observed. Dried OVA protein-loaded films rapidly deconstructed when rehydrated in saline solutions, releasing OVA as non-aggregated/non-degraded protein, suggesting that the structure of biomolecules integrated into these multilayer films are preserved during release. Using confocal fluorescence microscopy and an in vivo murine ear skin model, we demonstrated delivery of OVA from LbL films into barrier-disrupted skin, uptake of the protein by skin-resident antigen-presenting cells (Langerhans cells), and transport of the antigen to the skin-draining lymph nodes. Dual incorporation of OVA and CpG oligonucleotides into the nanolayers of LbL films enabled dual release of the antigen and adjuvant with distinct kinetics for each component; OVA was rapidly released while CpG was released in a relatively sustained manner. Applied as skin patches, these films delivered OVA and CpG to Langerhans Cells in the skin. To our knowledge, this is the first demonstration of LbL films applied for the delivery of biomolecules into skin. This approach provides a new route for storage of vaccines and other immunotherapeutics in a solid-state thin film for subsequent delivery into the immunologically-rich milieu of the skin. In parallel, we also developed biodegradable core-shell nanoparticles with a PBAE core enveloped by a phospholipid bilayer shell for cytosolic delivery, with a view towards delivery of messenger RNA (mRNA)-based vaccines. The pH-responsive PBAE component was chosen to promote endosome disruption, while the lipid surface layer was selected to minimize toxicity of the polycation core. mRNA was efficiently adsorbed via electrostatic interactions onto the surface of these net positively charged nanoparticles. In vitro, mRNA-loaded particle uptake by dendritic cells led to mRNA delivery into the cytosol with low cytotoxicity, followed by translation of the encoded protein in these difficult-to-transfect cells at a frequency of -30%. Particles also promoted cytosolic uptake of co-delivered anti-tumor toxins in tumor cells resulting in synergistic killing, demonstrating potential for cancer therapy. In vivo, particles loaded with mRNA administered intranasally or intratracheally in mice led to the enhanced expression of the reporter protein luciferase compared to naked mRNA. This system may thus be promising for noninvasive delivery of mRNA-based vaccines.
by Xingfang Su.
Ph.D.
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Mahadevegowda, Amoghavarsha. "Processing, microstructure and properties of polymer-based nano-composite dielectrics for capacitor applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fb974b13-2ec5-4104-9f80-45d1cb97eb48.
Повний текст джерелаАнотація:
The processing and properties of novel polymer-based nano-composite (PNC) dielectrics for capacitor applications has been studied. PNCs were fabricated via a vacuum based deposition technique and their micro/nano-structure, chemical and dielectric properties investigated. After process development and optimisation, co-deposited Al and nylon-6 PNCs had a dielectric constant k∼7 at an approximate Al volume fraction of 0.3 that agreed with analytical predictions if it was assumed that the Al transformed to an oxide in-situ and/or after deposition. The significant effect of absorbed water vapour and temperature on PNC dielectric properties was revealed using different types of post-deposition heat treatment. Alternately-deposited PNCs consisting of Al or Ag 2-20 nm layers sandwiched between nylon-6 layers were fabricated in which the overall PNC Al or Ag volume fraction was controlled by varying the nominal Al or Ag layer thickness. Ag layers comprised of discrete nano-islands that produced a nano-capacitor network effect that increased k to ∼11. In the case of Al layers, when the layer thickness was ≥ 5 nm, corresponding to a nominal volume fraction of 0.1, Al (core)-oxide (shell) nanoparticles were formed and the PNC dielectric constant increased to ∼19. The detailed nano-structure of the core-shell particles was studied using various types of transmission electron microscopy (TEM), and the elevations in dielectric constant ascribed to multiple-interface polarisation effects dependent on the formation of the core-shell structure. PNCs based on alternate deposition of Ti sandwiched in nylon-6, and then both Ti and Ag in nylon-6 were also fabricated, with k reaching ∼73 for Ag+Ti/nylon-6 PNCs. As well as Ti-based core (metal)-shell (oxide) particles, the Ag volume fraction was sufficiently high in the 10 nm nylon-6 layers to again form a nano-capacitor network that contributed to the overall device capacitance and effective dielectric constant. Again, various types of high magnification TEM were critical in resolving the Ti-based core-shell structure and its role in high-k behaviour. The vacuum-based alternate deposition technique has been developed to offer ease of operation, reliability, flexibility and applicability to chemically different filler and matrix systems in the fabrication of high-k PNC based capacitors, in which high-k performance relies critically on the formation of core (metal)-shell (oxide) particles in both Al and Ti based systems.
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Reichman, Aaron Michael. "Development of nano-characterization system for polymer film measurement and single BGA solder joint forming experiment." Diss., Online access via UMI:, 2007.
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Moberg, Thomas. "Creating nanopatterned polymer films for use in light-emitting electrochemical cells." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149396.
Повний текст джерелаАнотація:
Thermal nanoimprint lithography (T-NIL) is a cheap and fast technique to produce nanopatterns in polymeric materials. It creates these patterns by pressing a stamp down into a polymer film that has been heated above its glass transition temperature. These nanopatterned polymer films can be used in a wide variety of scientific fields, not the least the organic semiconductor industry. There the nanopatterned films have, among else, been used to improve the efficiency of organic light-emitting diodes (OLEDs). The light-emitting electrochemical cell (LEC), which is similar in structure to an OLED, also uses polymer films in their device structure but the light emitting layer also contains an electrolyte. However, it has not been shown if nanopatterns can improve LECs as well or if it is even possible to make an imprint in their polymer films that are mixed with an electrolyte. This thesis shows that T-NIL can be used to imprint nanopatterns in films made of poly(ethylene oxide) and the conjugated polymer Super Yellow. The best nanopatterns were produced by setting the imprint parameters to 85 °C, 10 bar, 1800 s for poly(ethylene oxide) and 115 °C, 20 bar, 1800 s for Super Yellow. Imprints were also performed on polystyrene but no nanopatterns could be produced. This was most likely because the stamp could not handle the high temperature that is required to make a nanopattern in polystyrene. The best imprint parameters of Super Yellow were then used to produce a pattern in a film made of Super Yellow mixed with the salt tetrahexylammonium tetrafluoroborate (THABF4) in order to be able to produce one imprinted and one reference LEC. The imprinted LEC had a luminosity of 139 cd/m2, an improvement of 20% compared to the reference’s 115 cd/m2 when operated under identical conditions. The forward direction and the angular dependent electroluminescence spectrum of the imprinted LEC clearly showed an effect not observed in the reference. These findings show that the polymer films used in a LEC can be imprinted with a nanopattern by using T-NIL. The imprinted films can be used to create functional LECs that show different behavior and a higher luminosity compared to a non-imprinted reference. If these results can be repeated it might be the starting point of a brighter future.
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Masclaux, Celine. "Etude de la structuration spontanée de films polymères en nano-impression thermique." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00770169.
Повний текст джерелаАнотація:
La lithographie de nano-impression par déstabilisation spontanée de polymère est unevariante de la technique de nano-impression thermique, et permet de limiter le contact directentre moule et polymère. Le but de cette thèse est d'étudier cette déstabilisation spontanée etde déterminer si elle peut conduire à la formation de nanostructures en dupliquant de façonpositive un moule nano-structuré. Ce procédé est influencé, en particulier, par la température,le champ électrique externe ou interne au niveau des interfaces moule - air - polymère, ainsique par la distance d séparant les structures du moule et la surface du polymère.Les études réalisées au cours de cette thèse se sont concentrées sur l'influence de cesdifférents paramètres. Nous avons montré que la formation de motifs dépend plus de l'effetde charges que de la température, dans la mesure où le polymère peut néanmoins fluer. Nousavons surtout mis en évidence le scénario de structuration suivant : une duplication positiveapparaît dans un premier temps, et est suivie, dans certains cas, d'un remplissage des cavitésdu moule conduisant à une duplication négative. Un modèle théorique a été utilisé pourcalculer la longueur d'onde de déstabilisation la plus favorable, et une comparaison avec nosrésultats expérimentaux a permis d'expliquer pourquoi et dans quels cas la structurationfinale est positive ou négative. Une investigation a été accomplie sur la déstabilisationspontanée de substrats souples, mais la grande épaisseur des films conduit à unedéstabilisation de grande longueur d'onde, et donc à un remplissage complet du moule.
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Morelli, Carolina Lipparelli. "Développement et étude des propriétés des films et des pièces injectées de nano-biocomposites de nanowhiskers de cellulose et de polymères biodégradables." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI018/document.
Повний текст джерелаАнотація:
Notre travail a pour objectif l'étude de l'influence de l'ajout de nanocristaux de cellulose dans des matrices biodégradables sur leurs propriétés. Des films composites et des pièces injectées ont été préparés et caractérisés. Dans ce but, ont été choisis comme matrices le poly(acide lactique), PLA, et le poly (butylène adipate-co-téréphtalate)), PBAT. Deux matières première d'où des nanocristaux de celulose ont été extraites ont été sélectionnées : le bois balse et la cellulose microcrystalline (CMC). En raison du caractère fortement polaire des nanocristaux de cellulose différentes voies de modifications chimiques de la surface de ces particules ont été testées afin d'assurer une bonne dispersion de ceux-ci lorsqu'ils sont ajoutés à des matrices polymères de polarité inférieure. En effet, les approches testées étaient: (a) le greffage de deux types d'isocyanates, dont l'un aliphatique et l'autre aromatique: l'octadécyl isocyanate (NCC_oct) et le phényl-butyle isocyanate (NCC_fb), respectivement; (b) le greffage de poly(butylène glutarate) à travers la technique de polymérisation in situ (NCC_PBG); (c) le greffage de l'acide polyacrylique à travers la technique appelée click chemistry (NCC_PA); et (d) la silanisation avec le - methacryloxy-propyle-trimethoxy-silane(NCC_MPS). Les NCCs initiaux et modifiés ont été ajoutés aux matrices de PBAT ou du PLA par procédés de mélanges à partir de solution (casting) ou à partir de l'état fondu (par extrusion ou en utilisent un homogénisateur de type Drais). En général, la modification chimique de la surface de NCC a augmenté la résistance thermique de celui-ci, a diminué son caractère hydrophile et a amélioré la dispersion des NCCs dans les matrices de PLA et PBAT. Cela a provoqué des augmentations encore plus grandes dans les propriétés de ces polymères, en fonction du type de modification et du procédé de fabrication utilisé. La caractérisation des nanocomposites a démontré que, en général, l'addition des NCCs a augmenté le module d'élasticité de la matrice et a conservé sa rigidité même à températures relativement élevées. Des niveaux plus élevés de NCC conduisent à de plus grandes augmentations de la rigidité. La perméabilité à la vapeur d'eau de PBAT a été réduite par l'introduction de NCC et n'a pas changé dans le cas du PLA. Les résullts de ces travaux ont indiqué de bonnes perspectives concernant l'utilisation des nanocristaux de cellulose comme élément de renfort de matrices polymères. De manière générale, le présent travail a démontré que les NCCs étaient capables d'améliorer les propriétés mécaniques, thermiques et de barrières du PBAT et du PLA, qui sont deux polymères biodégradables largement utilisés dans les applications de films ou de pièces plastiques. De plus, les résultats montrent qu'il est possible de modifier la polarité des NCC en les soumettant à des modifications chimiques de surface afin d'éviter leur agglomération par la formation de ponts de liaisons hydrogènes et de les rendre compatibles avec différentes matrices polymères. Ces modifications chimiques tendent aussi à élever la résistance thermique des NCCs. De cette manière, les procédés à l'échelle industrielle comme l'extrusion et l'injection peuvent être utilisés et fournissent de bons résultatsThis study aimed at evaluating the potential of application of cellulose nanocrystals as reinforcing elements of biodegradable polymeric matrices, in the films and injection molded pieces applications. Two polymeric matrices with different properties were used, namely: poly(butylene adipate-co-terephthalate), PBAT, and poly(lactic acid), PLA. For the extraction of cellulose nanocrystals (NCC), two sources were selected: microcrystalline cellulose (CMC) and balsa wood . Due to the high polarity of cellulose nanocrystals, different approaches of surface chemical modifications of these particles were tested, in order to ensure their good dispersion when added to polymeric matrices of lower polarity. They were: a) chemical modification with two types of isocyanates, an aliphatic one (octadecyl isocyanate) and an aromatic one (phenylbutyl isocyanate); b) grafting of poly (butylene glutarate) using the in situ polymerization technique; c) silanization treatment; and d) grafting of poly(acrylic acid) through click chemistry technique. Modified and unmodified NCCs were processed with PBAT and PLA by casting or melt extrusion processing techniques. In general, the chemical modification of NCC surface increased their thermal resistance, decreased their polarity and improved their dispersion into PLA and PBAT matrices. Some of these treatments, as well as the processing conditions enabled an increase in the overall mechanical properties of the polymers. Thus, the characterization of the nanocomposites showed that NCC addition increased the elastic modulus of the matrix and retained its higher stiffness even under relatively high temperatures. Higher NCC contents led to larger increases in the stiffness of the ensuing composites. The water vapor permeability of PBAT was also reduced with the introduction of NCC. This work points out several potential good perspectives for the use of celulose nanocrystals as reinforcing elements of polymeric matrices. It showed also that it is possible to obtain significant improvements in the polymer properties using the same processing techniques as those used at industrial scale, such as melt extrusion and injection molding
O presente estudo de doutorado teve como objetivo avaliar o potencial deaplicação de nanocristais de celulose como reforço em matrizes poliméricasbiodegradáveis, em aplicações de filmes ou em peças moldadas por injeção.Duas matrizes poliméricas de diferentes propriedades foram utilizadas paraestudo nessas aplicações, sendo elas: poli(butileno adipato-co-tereftalato),PBAT, e poli(ácido láctico), PLA. Foram também selecionadas duas fontes paraextração dos nanocristais de celulose (NCC): a celulose microcristalina (CMC)e a madeira balsa.Devido ao caráter altamente polar dos nanocristais de celulose diferentesrotas de modificações químicas superficiais dessas partículas foram testadas,visando garantir a boa dispersão dos mesmos quando adicionados às matrizespoliméricas de menor polaridade. Foram elas: a) modificação química com doistipos de isocianatos, sendo um de cadeia alifática (octadecil isocianato) e outrode cadeia aromática (fenilbutil isocianato); b) enxertia do poli(butileno glutarato)através da técnica de polimerização in situ; c) tratamento de silanização com -metacriloxi-propil-trimetoxi-silano; d) enxertia de poli(ácido acrílico) através datécnica de click chemistry.NCC modificados e não modificados foram processados com PBAT ouPLA através de mistura com o polímero em solução (casting) ou no estadofundido (extrusão ou homogeneizador de alta rotação do tipo Drais).De modo geral, modificações químicas superficiais dos NCC aumentarama estabilidade térmica dos mesmos, diminuíram sua polaridade e melhoraram adispersão dos NCC nas matrizes de PBAT ou PLA. Isso fez com queincrementos ainda maiores nas propriedades desses polímeros pudessem serxxivalcançados, dependendo do tipo de modificação e do processo de misturautilizados.A caracterização dos nanocompósitos obtidos mostrou que a adição deNCC elevou o módulo elástico das matrizes e conservou sua maior rigidezmesmo em temperaturas relativamente elevadas, sendo que maiores teores deNCC levaram a maiores aumentos na rigidez. A permeabilidade a vapor deágua do PBAT também foi reduzida com a introdução dos NCC e não foialterada no caso do PLA.Os resultados desse trabalho apontaram boas perspectivas no uso dosnanocristais de celulose como reforços de matrizes poliméricas. Tambémmostraram que é possível obter melhorias nas propriedades de polímerosmesmo através da utilização de processos de maior reprodutibilidade emescala industrial, como extrusão e injeção
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Ayche, Kenza. "Propriétés mécaniques et structurales d'encapsulants polymères utilisés en microélectronique : effet de la température et de l'humidité." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1005/document.
Повний текст джерелаАнотація:
L’engouement mondial pour les appareils nomades et la course à la sobriété énergétique font de la diminution de la taille des systèmes microélectroniques (MEMS) un enjeu majeur pour les prochaines années. Les micro batteries au lithium sont aujourd'hui le moyen le plus efficace pour stocker et alimenter des dispositifs avec une très forte densité énergétique. Les incorporer dans des cartes de crédit comportant un écran et des touches intégrés est l’un des défis que relèvent les multinationales comme ST Micro Electronics. Ces micro batteries contiennent cependant du lithium métallique qui peut s'avérer très dangereux quand il est en contact avec de l’eau ou de l’air humide. Ainsi, afin de protéger les composants à une exposition à l’humidité, une encapsulation de l’ensemble de la batterie est nécessaire. L'encapsulation polymère a l’avantage, comparativement à d’autres matériaux, de présenter un faible coût de mise en forme et un faible poids. Cependant, de tels systèmes d'encapsulation sont aujourd'hui insuffisants pour garantir une durée de vie de plusieurs années des composants car en présence d’humidité ou d’une variation de température importante la tenue mécanique des assemblages peut être fragilisée. L'objectif de la thèse est donc de réaliser et d'étudier le comportement mécanique et structural d’assemblage de couches minces de polymères et de métaux en température et en humidité. Deux types de polymères ont été choisis pour ce projet :1. Le chlorure de polyvinylidène (PVDC), un polymère commercial très utilisé pour ses bonnes propriétés barrières à l'eau 2. Un oligomère acrylate reticulable par voie thermique et UV synthétisé au sein de l'IMMMThe increasing number of mobile devices and the race to energy sobriety make the decrease of the size of microelectronic systems (MEMS) a major challenge. Today, Lithium micro batteries are currently the best solution for high-power-and-energy applications. Incorporate them into credit cards containing a screen or associate them to electronic sensors for the supervision is the challenge which raises international companies such as ST Microelectronics. However, these micro batteries contain some lithium metal which can be dangerous if the metallic lithium is in contact with water or humid air. In addition, the substance can spontaneously ignite in the contact of the humidity. So, in order to avoid the problems of safety, we absolutely have to protect the lithium contained in our micro batteries using an encapsulation layer. Polymeric encapsulation has the advantage, compared with other materials (ceramic, metal), to present a moderate cost of shaping and a low weight. However, such systems of encapsulation are today insufficient to guarantee a satisfactory life cycle of components. Indeed, in the presence of humidity or of a too important temperature variation, the mechanical assemblies can be weakened and engender an irreparable break. The objective of the thesis is therefore to realize and study the mechanical and structural behavior of assembly of thin layers of polymers and metals in temperature and humidity.Two types of polymers were selected for this project:1. Polyvinylidene chloride (PVDC), a commercial polymer widely used for its good barrier properties to water.2. A thermally and UV-crosslinkable acrylate oligomer synthesized in the IMMM
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Saxena, Shubham. "Nanolithography on thin films using heated atomic force microscope cantilevers." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08302006-223629/.
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Geng, Kun. "Dynamic studies of nano-confined polymer thin films." 2017. https://hdl.handle.net/2144/20711.
Повний текст джерелаАнотація:
Polymer thin films with the film thickness (h0) below ~ 100 nm often exhibit physical properties different from the bulk counterparts. In order to make the best use of polymer thin films in applications, it is important to understand the physical origins of these deviations. In this dissertation, I will investigate how different factors influence dynamic properties of polymer thin films upon nano-confinement, including glass transition temperature (Tg), effective viscosity (ηeff) and self-diffusion coefficient (D).
The first part of this dissertation concerns the impacts of the molecular weight (MW) and tacticity on the Tg’s of nano-confined polymer films. Previous experiments showed that the Tg of polymer films could be depressed or increased as h0 decreases. While these observations are usually attributed to the effects of the interfaces, some experiments suggested that MW’s and tacticities might also play a role. To understand the effects of these factors, the Tg’s of silica-based poly(α-methyl styrene) (PαMS/SiOx) and poly(methyl methacrylate) (PMMA/SiOx) thin films were studied, and the results suggested that MW’s and tacticities influence Tg in nontrivial ways.
The second part concerns an effort to resolve the long-standing controversy about the correlation between different dynamics of polymer thin films upon nano-confinement. Firstly, I discuss the experimental results of Tg, D and ηeff of poly(isobutyl methacrylate) films supported by silica (PiBMA/SiOx). Both Tg and D were found to be independent of h0, but ηeff decreased with decreasing h0. Since both D and ηeff describe transport phenomena known to depend on the local friction coefficient or equivalently the local viscosity, it is questionable why D and ηeff displayed seemingly inconsistent h0 dependencies. We envisage the different h0 dependencies to be caused by Tg, D and ηeff being different functions of the local Tg’s (Tg,i) or viscosities (ηi). By assuming a three-layer model, we were able to account for the experimental data and resolve the inconsistency. By extending the same ideas to the analogous data of silica-based polystyrene films (PS/SiOx), we found a resolution to the inconsistency regarding the effects of nano-confinement on the dynamics of polymer thin films.
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Wu, Ping-Ying, and 吳品瑩. "A study of electropolymerization PEDOT nano conductive polymer films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/wyj7jf.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
有機高分子研究所
101
Poly-3,4-ethylenedioxythiophene(PEDOT) finds many applicaton in OLED, LCD, DSSC, etc. It is a very important conjugate polymers. In this thesis, EDOT is polymerized by electrochemical method. Many additives are added to analyze to effects of dopants on the conductivity. It is found that HCl has dramatic influence on the PEDOT conductivity. On the other hand, copolymer is used to increase the thermal durability. They are investigated by FTIR, NMR, etc. The stracture properties relationship is elucidated in this thesis.
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Wu, Shing-Trong, and 吳欣璁. "Study and application of nano-sized polymer dispersed liquid crystal films." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/78228837712406677760.
Повний текст джерелаАнотація:
博士國立成功大學
物理學系碩博士班
93
Abstract The researches and applications of two nano-sized polymer dispersed liquid crystal (PDLC) devices including 2D diffraction gratings and Bragg gratings were investigated in the study. The 2D PDLC gratings are fabricated by light controlled phase separation using a photomask in UV curing. The sizes of LC droplets are ~200nm and formed periodically distributed in the film. The diffracted beams from the 2D PDLC grating were switched by rotating the analyzer and/or applying a voltage. The 2D PDLC gratings can be systematically constructed to support such a beam switching application. The Bragg gratings are fabricated from LC/pre-polymer mixtures using holographic recording. The 1D grating consists of periodic nano-sized (<200nm) LC droplets and polymer lamellae in the film. Doped with a laser dye whose emission spectrum overlaps the reflection spectrum of the grating, the HPDLC reflection grating can be lased at the band edges of the reflection band gap.
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Suran, Swathi. "Bright-field Nanoscopy." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4310.
Повний текст джерелаАнотація:
This thesis discusses the design and development of a technique which focuses on visualization of nanoscale structures using a regular bright-field optical microscope without the need of any additional fluorescent tags. We refer to this technique as Bright-field Nanoscopy (BFN). The mechanism involves a device which works on the phenomenon of interference producing strong thickness dependent colour response of ultra-thin films of Germanium on an optically thick Gold film. The Ge films get etched due to the dissolution of its oxide, GeO2 in water. Any nanoscale object placed on the Ge device, impedes the transport of water to the Ge film resulting in a differential transverse etch rate and consequently giving rise to a local colour difference. The generated colour contrast was significant enough to be picked up by any conventional optical microscope. Using this technique, we were able to directly image grain boundaries in single layer graphene and single metal nanoparticles.
Additionally, we demonstrate the use of this technique for direct visualization of water transport through polymer nano-films. For the first time, the prominent odd-even effect known in polyelectrolyte multilayers (PEMs) was directly visualized. Further, we used this technique to directly image the nanoscale organization of the interpenetrating networks in polymer thin films. We will also discuss how this technique could also be extended to measuring ion transport across nano-membranes.
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LIN, WEN-ZHONG, and 林文中. "The Influence of Micro and Nano Fillers on the Thermal Properties of Polymer Composite Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/tf9kdj.
Повний текст джерелаАнотація:
碩士國立虎尾科技大學
光電工程系光電與材料科技碩士班
106
The size of electronic products is becoming smaller and lighter and easier to carry today, but the computing power of the core processor is growing day by day. The heat generated from the CPU is likely to cause high temperature in the device. The performance, stability, lifespan, and user comfortability of electronic products could be reduced and even cause shot down of the system, since the thermal released from the CPU is accumulated quickly and difficult to dissipate from the electronic device. Therefore, how to remove the derived heat away from the heat source to avoid accumulation becomes quite important. In this study, we combined the electronic and phononic heat transfer mechanisms to increase the thermal conductivity of the composite coating films by filling a conductive polymer PEDOT between the BN, AlN, SiC micro-nano ceramic fillers gap. The heat is radiated from the surface of the composite films due to the high infrared emissivity fillers were connected by the conductive polymer. The highest thermal conductivity and the infrared emissivity of the composite coating can achieve 148.66 (W/M∙K) and 0.977, respectively. The results of this study also could be applied to the devices that are lightweight, fan-free or energy-efficient required devices in the future.
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Sharma, Bhupendra Kumar. "Synthesis and characterization of ZnO: thin films, nanostructures, polymer/nano ZnO composites and ZnO based heterojunction." Thesis, 2010. http://localhost:8080/iit/handle/2074/4377.
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Pahal, Suman. "Molecular Transport in Polyelectrolyte Multilayers." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3758.
Повний текст джерелаАнотація:
Layer-by-layer assembly of polyelectrolytes is a simple technique based on the self-assembly of polycations and polyanions mainly by electrostatic interactions, which has gained considerable scientific interest for its versatility of applications. Ease of fabrication process, inexpensive approach and use to coat surfaces with various geometries prompts the researchers to select this technique not only for the surface modification applications but also to study the processes which exploit the 3D matrix properties of polyelectrolyte multilayer films (PEMs). Recent advances have been made where PEMs coatings have been utilized for their bio-applications like drug delivery and in tissue engineering for modifying the biomaterial's surfaces. In the field of drug delivery and tissue engineering the location and availability of the constituent molecules is very important, which is defined by their ability to diffuse through the encapsulating material or reservoir. So the main objective of this thesis is to understand the transport of molecules in ultrathin Polyelectrolyte Multilayer Films in lateral as well as transverse direction to the substrate. To study this transport behaviour in PEMs, we have employed various strategies which can enhance or suppress the diffusivity across PEMs. Thus, understanding the diffusion at nanoscale resolution will lead us to design better host materials for loading of drugs and growth factors for various biomedical applications.
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Pahal, Suman. "Molecular Transport in Polyelectrolyte Multilayers." Thesis, 2016. http://etd.iisc.ernet.in/2005/3758.
Повний текст джерелаАнотація:
Layer-by-layer assembly of polyelectrolytes is a simple technique based on the self-assembly of polycations and polyanions mainly by electrostatic interactions, which has gained considerable scientific interest for its versatility of applications. Ease of fabrication process, inexpensive approach and use to coat surfaces with various geometries prompts the researchers to select this technique not only for the surface modification applications but also to study the processes which exploit the 3D matrix properties of polyelectrolyte multilayer films (PEMs). Recent advances have been made where PEMs coatings have been utilized for their bio-applications like drug delivery and in tissue engineering for modifying the biomaterial's surfaces. In the field of drug delivery and tissue engineering the location and availability of the constituent molecules is very important, which is defined by their ability to diffuse through the encapsulating material or reservoir. So the main objective of this thesis is to understand the transport of molecules in ultrathin Polyelectrolyte Multilayer Films in lateral as well as transverse direction to the substrate. To study this transport behaviour in PEMs, we have employed various strategies which can enhance or suppress the diffusivity across PEMs. Thus, understanding the diffusion at nanoscale resolution will lead us to design better host materials for loading of drugs and growth factors for various biomedical applications.
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Liang-Ren, Huang, and 黃良仁. "Electrochemical Leveling Effect on Multi-Aromatic Monomer Films to Prepare Robust Conducting Polymer Nano/MicroFilms by Vapor Deposition Combined with Electropolymerization." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/97427083123488325647.
Повний текст джерелаАнотація:
碩士南台科技大學
化學工程與材枓工程系
95
Multi-aromatic conducting polymer films, poly(N-phenyl-1-naphthylamine) (PPNA), were prepared by using a combination of vapor deposition and electrochemical polymerization. The PNA monomer film was vapor deposited on an indium-tin oxide (ITO) glass, and was then electropolymerized using cyclic voltammetry in 1N HClO4 aqueous solution. An electrochemical rubbing effect happened on the monomer film using the above combined process, producing a robust electrode material of PPNA film in the electrochromic device: ITO / PPNA film // PU-LiClO4 // PEDOT:PSS / ITO, where poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) is PEDOT:PSS, and polyurethane is PU. Short response time (ca. 10 s) was attained from coloring to bleaching processes. After 200 switching, the stable coulombic efficiency and optical contrast possess the values of 108 and 28%, respectively. On the othe hand ,we report the electrochromic charateristics of a triphenylamine-based hole-transporting material, N, N’-diphenyl-N, N’-bis(3-methylphenyl)-1, 1’-biphenyl-4, 4’-diamine (TPD) employing the cyclic voltammetry and spectroelectrochemical methods. To assemble the dual-type electrochromic devices using different thickness (250, 400, and 1000 nm) of TPD films: ITO/TPD//PU-LiClO4//PEDOT/ITO, the optical contrast of the devices increases with increasing the TPD film thickness, whereas the 1000 nm TPD film showed relatively excellent stability; the color of the film changed from orange-brown, transparent, and dark blue at -2.0, 0.0, and +2.0 V (vs. PEDOT), respectively, where PEDOT is poly(3,4-ethylenedioxythiophene) -poly(4-styrenesulfonate).
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Satapathy, Srinibas. "Investigations Into The Bulk Single Crystals, Nano Crystal Composites And Thin Films Of Ferroelectric Materials For Pyroelectric Sensor Applications." Thesis, 2009. https://etd.iisc.ac.in/handle/2005/1044.
Повний текст джерелаАнотація:
In this thesis, the results pertaining to various investigations carried out on Triglycine sulphate (TGS) single crystals, polyvinylidene fluoride (PVDF) films, lithium tantalate (LT)/PVDF nanocomposites and LT thin films are presented with emphasis on the characteristics that are crucial for their use in pyroelectric sensors. TGS single crystals (size 68 x 45 x 42 mm3), which have high pyroelectric coefficients, were grown by slow cooling method using newly designed platform technique based crystal growth work stations. The problem of slow growth rate along c-direction was overcome by placing (010) oriented seeds on the platform. The grown TGS crystals were used for the fabrication of the laser energy meter and temperature sensor. One drawback of TGS is its low Curie temperature (490C). As a consequence when the operating temperature approaches the Curie temperature, the crystals start depolarizing owing to the movement of domains. As a result the linearity of the devices gets affected and restricts the use of TGS. Therefore pyroelectric materials possessing higher Curie temperatures and larger pyroelectric coefficients than that of TGS are desirable. LT in single crystalline form having Curie temperature of ≈6000C has already been in use for pyroelectric device applications. However, growing stoichiometric LT single crystal is very difficult. On the other hand PVDF polymer films (Tc≈1800C) have low pyrolectric coefficients and difficult to pole electrically. Therefore efforts were made to prepare LT/PVDF nanocrystal composites to increase the pyroelectric coefficient of PVDF and to reduce the poling field. Nanoparticles of LT were prepared using sol-gel route. Spherical nanoparticles of size 20-40nm were prepared from sol by adding oleic acid to it. These nanoparticles were characterized using XRD, TEM, DSC and Raman spectroscopy. PVDF films with large percentage of β-phase (ferroelectric phase) were fabricated from solutions prepared using dimethylsulphoxide (DMSO) solvent. PVDF films (30µm thick), embedded with 20-40nm sized nanocrystallites of LT were fabricated to utilize them for pyroelectric sensor applications. The ferroelectric and pyrolectric properties of nano composite films were studied for sensor applications point of view. As a replacement for the single crystals of LT in pyroelectric sensors, investigations were carried out on oriented LT thin films. The studies on LT thin films yielded promising results which could be exploited for pyroelectric sensor applications.
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Satapathy, Srinibas. "Investigations Into The Bulk Single Crystals, Nano Crystal Composites And Thin Films Of Ferroelectric Materials For Pyroelectric Sensor Applications." Thesis, 2009. http://hdl.handle.net/2005/1044.
Повний текст джерелаАнотація:
In this thesis, the results pertaining to various investigations carried out on Triglycine sulphate (TGS) single crystals, polyvinylidene fluoride (PVDF) films, lithium tantalate (LT)/PVDF nanocomposites and LT thin films are presented with emphasis on the characteristics that are crucial for their use in pyroelectric sensors. TGS single crystals (size 68 x 45 x 42 mm3), which have high pyroelectric coefficients, were grown by slow cooling method using newly designed platform technique based crystal growth work stations. The problem of slow growth rate along c-direction was overcome by placing (010) oriented seeds on the platform. The grown TGS crystals were used for the fabrication of the laser energy meter and temperature sensor. One drawback of TGS is its low Curie temperature (490C). As a consequence when the operating temperature approaches the Curie temperature, the crystals start depolarizing owing to the movement of domains. As a result the linearity of the devices gets affected and restricts the use of TGS. Therefore pyroelectric materials possessing higher Curie temperatures and larger pyroelectric coefficients than that of TGS are desirable. LT in single crystalline form having Curie temperature of ≈6000C has already been in use for pyroelectric device applications. However, growing stoichiometric LT single crystal is very difficult. On the other hand PVDF polymer films (Tc≈1800C) have low pyrolectric coefficients and difficult to pole electrically. Therefore efforts were made to prepare LT/PVDF nanocrystal composites to increase the pyroelectric coefficient of PVDF and to reduce the poling field. Nanoparticles of LT were prepared using sol-gel route. Spherical nanoparticles of size 20-40nm were prepared from sol by adding oleic acid to it. These nanoparticles were characterized using XRD, TEM, DSC and Raman spectroscopy. PVDF films with large percentage of β-phase (ferroelectric phase) were fabricated from solutions prepared using dimethylsulphoxide (DMSO) solvent. PVDF films (30µm thick), embedded with 20-40nm sized nanocrystallites of LT were fabricated to utilize them for pyroelectric sensor applications. The ferroelectric and pyrolectric properties of nano composite films were studied for sensor applications point of view. As a replacement for the single crystals of LT in pyroelectric sensors, investigations were carried out on oriented LT thin films. The studies on LT thin films yielded promising results which could be exploited for pyroelectric sensor applications.
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Mullapudi, Praveena. "Study of Optical Properties of Semiconductor Quantum Dot Based Hybrid Nano Assemblies." Thesis, 2016. https://etd.iisc.ac.in/handle/2005/2825.
Повний текст джерелаАнотація:
Over the last few decades, a vast research is going on, to study the optical properties of the nano particles i.e., metal and semiconductors thoroughly. Till date most of the optical studies are based on single particle measurement of a quantum dot (QD) or a chromophore under the influence of an external plasmonic field stimulus. In this the-sis, we tried to address the energy transfer at non local level on a layer of compact, monolayer QD assemblies over micro meter range. The energy transfer occurs in the presence of external field of metal particles or nanorods leads to the enhancement or quenching the emission from a layer of QDs.
Chapter 1 is introduction to the basic theoretical aspects of excitons in semiconductor (QDs) and its optical properties under strong confinement regime. The discussion is followed with the optical properties of gold nanoparticles and rods, describing size and shape dependent variation of absorption properties, based on Mie and Mie-Gans theory. Theoretical background of collective effects in QD assemblies based on exciton-plasmonic interactions at single particle level as well as polarization based plasmo-nenhanced fluorescence has been subjected. Experimental techniques are explained in chapter 2 which contains the details of the synthesis of polymer capped nanoparticles with the respective characterization. A discussion on the synthesis methods for cadmium selenide QDs, gold nano particles and the rods with different polymer cap-ping legends and the related capping exchange methods. The thin film preparation of QD monolayers as well as hybrid nano assemblies using several techniques, i.e., Langmuir-Blodgett (LB), dip coat methods are provided. Further the details of surface morphology of the prepared thin films has been studied by different microscopic techniques i.e., atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The details of the PL emission measurements of these hybrid arrays using confocal, Raman and polarization based near field scanning optical microscope (NSOM) modes followed with the life time measurements. In third chapter, the substantial strong coupling and collective emission regime is engineered in the QD monolayer films embedded with tiny gold nano particles keeping the QD density same. Tuning the photoluminescence (PL) of semiconducting QD assemblies using small Au NPs in different ratio, different packing density and extent of spectral overlap between QD photoluminescence and the metal nanoparticle absorbance has been discussed.
We provided possible experimental and theoretical evidence for the plasmon-mediated emergence of collective emission and enhanced quantum efficiency in these QD films with the consolidation of multiple emitters and multiple NPs. The quantum efficiency of these hybrid assemblies is further explored with different material as well as the size effect of metal nano particles.
Chapter 4 comprises the experiment results of the self-assembled compact and partially aligned gold nano rod (GNR) arrays on QD monolayer films. We experimentally demonstrated the quantum efficiency of these QD hybrid assemblies is gaining max-imum when the longitudinal surface plasmon resonance (LSPR) absorption maxima of GNR arrays is resonant with the QD monolayer PL maxima and is always non-existent for the off resonant case. Further, we reported the variability in the size and morphology of these GNR domains leads to the maximum achieved enhancement as well as anisotropy value in comparison with isolated rods and the explored conditions to further enhance the efficiency in these QD hybrid assemblies.
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Mullapudi, Praveena. "Study of Optical Properties of Semiconductor Quantum Dot Based Hybrid Nano Assemblies." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2825.
Повний текст джерелаАнотація:
Over the last few decades, a vast research is going on, to study the optical properties of the nano particles i.e., metal and semiconductors thoroughly. Till date most of the optical studies are based on single particle measurement of a quantum dot (QD) or a chromophore under the influence of an external plasmonic field stimulus. In this the-sis, we tried to address the energy transfer at non local level on a layer of compact, monolayer QD assemblies over micro meter range. The energy transfer occurs in the presence of external field of metal particles or nanorods leads to the enhancement or quenching the emission from a layer of QDs.
Chapter 1 is introduction to the basic theoretical aspects of excitons in semiconductor (QDs) and its optical properties under strong confinement regime. The discussion is followed with the optical properties of gold nanoparticles and rods, describing size and shape dependent variation of absorption properties, based on Mie and Mie-Gans theory. Theoretical background of collective effects in QD assemblies based on exciton-plasmonic interactions at single particle level as well as polarization based plasmo-nenhanced fluorescence has been subjected. Experimental techniques are explained in chapter 2 which contains the details of the synthesis of polymer capped nanoparticles with the respective characterization. A discussion on the synthesis methods for cadmium selenide QDs, gold nano particles and the rods with different polymer cap-ping legends and the related capping exchange methods. The thin film preparation of QD monolayers as well as hybrid nano assemblies using several techniques, i.e., Langmuir-Blodgett (LB), dip coat methods are provided. Further the details of surface morphology of the prepared thin films has been studied by different microscopic techniques i.e., atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The details of the PL emission measurements of these hybrid arrays using confocal, Raman and polarization based near field scanning optical microscope (NSOM) modes followed with the life time measurements. In third chapter, the substantial strong coupling and collective emission regime is engineered in the QD monolayer films embedded with tiny gold nano particles keeping the QD density same. Tuning the photoluminescence (PL) of semiconducting QD assemblies using small Au NPs in different ratio, different packing density and extent of spectral overlap between QD photoluminescence and the metal nanoparticle absorbance has been discussed.
We provided possible experimental and theoretical evidence for the plasmon-mediated emergence of collective emission and enhanced quantum efficiency in these QD films with the consolidation of multiple emitters and multiple NPs. The quantum efficiency of these hybrid assemblies is further explored with different material as well as the size effect of metal nano particles.
Chapter 4 comprises the experiment results of the self-assembled compact and partially aligned gold nano rod (GNR) arrays on QD monolayer films. We experimentally demonstrated the quantum efficiency of these QD hybrid assemblies is gaining max-imum when the longitudinal surface plasmon resonance (LSPR) absorption maxima of GNR arrays is resonant with the QD monolayer PL maxima and is always non-existent for the off resonant case. Further, we reported the variability in the size and morphology of these GNR domains leads to the maximum achieved enhancement as well as anisotropy value in comparison with isolated rods and the explored conditions to further enhance the efficiency in these QD hybrid assemblies.
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Qi, Dongping. "On near-free-surface dynamics of thin polymer films." Thesis, 2009. http://hdl.handle.net/10012/4326.
Повний текст джерелаАнотація:
Studies show that dynamical properties of ultra-thin polymer films deviate from those of bulk materials. Despite some controversial issues, there is growing evidence indicating that the interfacial properties play a key role for observed dynamical anomalies. However, how and how much the interfacial properties affect the average dynamics of the nanometer scale systems are still elusive. In this work, we developed several novel techniques to investigate near-free-surface dynamics of thin polymer films. We studied surface dynamics of glassy i-PMMA films using a nano surface hole relaxation technique: a strong substrate property dependence and an unexpected molecular weight dependence were observed; we found that a local Tg of ~40K below bulk Tg could be assigned to the surface region. We used nano gold particle embedding to study PS surface dynamics: enhanced surface dynamics and weak temperature dependence were observed for the surface region; a depth profile with the nm resolution was observed; viscous liquid-like and soft solid-like properties were observed in the first 5.5nm and next 3.3 nm regions in PS films; no molecualr weight dependence was found in glassy PS films. We built a low level noise measurement system to study the thermal polarization noise in PVAc films: cooperative rearranging dynamics were evidenced; the noise power spectral density (PSD) is found to fluctuate around a certain average level without discernable peak shift; we observed some relatively big jumps or fluctuations in successive integrated PSD’s, which indicate some energy exchange between different microscopic domains in glassy polymer systems. We developed a novel nano rheology AFM technique to study the near-free-surface dynamics of thin polymer films: enhanced near-free-surface dynamics with weak temperature dependence are observed for PVAc films, which is similar with the PS case.
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Fagan, Matthew D. "A Novel Process for Continuous Thermal Embossing of Large-Area Nanopatterns onto Polymer Films." 2008. https://scholarworks.umass.edu/theses/200.
Повний текст джерелаАнотація:
As imprint lithography becomes commonplace in industrial manufacturing, the need for fast, reliable modifications to the process are of great importance. In particular, the Roll-to-Roll Nanoimprint Lithography (R2RNIL) method has been proven to yield large areas of continuous, robust patterns in the micro- and nanometer range. A thermal embossing R2RNIL system has been developed that is capable of providing a mold heating rate of 100ºC/s with sufficient temperature control to produce large-area patterns continuously at a rate in excess of four feet per minute. This process uses a novel looped-conveyor mold, allowing longer continuous patterns to be produced with superior temperature control than other methods of R2RNIL. Various patterns in the micro- and nanometer domains were replicated using this process.
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Shen, Xiaojun, Sung Yi, Lallit Anand, and Kaiyang Zeng. "Studies on Nano-Indentation of Polymeric Thin Films Using Finite Element Methods." 2002. http://hdl.handle.net/1721.1/3990.
Повний текст джерелаАнотація:
In this paper, the numerical simulation for nano-indentation is performed to measure time-dependent behavior of polymeric films. The possibility to extract the relaxed shear modulus of the polymer is evaluated using a rigid ball indenter. The viscoelastic behavior of the polymer was represented by the standard model. The effects of Poisson’s ratio are also discussed.Singapore-MIT Alliance (SMA)
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Huang, Chun-Kuo, and 黃俊國. "Bulge test and mechanical properties measurement of nano-structure polymeric thin films." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/96837616676691086954.
Повний текст джерелаАнотація:
碩士國立清華大學
材料科學工程學系
93
In last few decades, the applications of thin film have become more and more widely. In order to guarantee the long-term operation according to their specification, mechanical properties of thin film are highly desirable. Unfortunately, as the scale level of film structure decreasing, it becomes increasingly difficult to measure its mechanical properties. Bulge test is a useful method for characterize mechanical properties in thin films. In bulge test, a pressure is applied to the backside of the thin film uniformly, making the free-standing thin film to deflect. By measuring the pressure applied and the deflection height of the thin film, a Pressure vs. deflection height curve can be obtained and mechanical properties of the film are determined from the curve fitting process. In bulge test, the accuracy of the measurement is significantly influenced by the sample geometry. The process of free-standing thin film fabrication will be described in this thesis. A big advantage of this test over other micromechanical test lies in the relatively simple stress-strain state in the sample since the stress state in the film is biaxial. We apply bulge test to measure mechanical properties of polymeric thin film with thickness from several tenth to several hundredth nanometer. In this thesis, the polymeric thin film we tested is mr-I 8030 (Micro Resist Technology) which is used in nanoimprint lithography. The results are compared with data obtain by nanoindentation. The Young’s moduli measured by nanoindentation are about 20% to 50% greater than those measured by bulge test. This result can be viewed as the effect of substrate and the densification of thin film material under indent point. We also introduce a method to estimate Poisson ratio of thin film material. Poisson ratio, ν, can be calculated from the relationship between biaxial modulus and plane strain modulus. This idea can be carried out by conducting bulge test on square and long rectangular free-standing thin films.
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Liu, Yajing. "Rapid nano-patterning of polymeric thin films with a GA⁺ focused ion beam /." 2005. http://wwwlib.umi.com/dissertations/fullcit/3161255.
Повний текст джерела
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Fernandes, Joana Gonçalves. "Writing/erasing 3D micro and nano wrinkles in flexible elastomers for volatile organic compounds sensor." Master's thesis, 2014. http://hdl.handle.net/10362/13930.
Повний текст джерелаАнотація:
Micro/nano wrinkled patterns on cross-linked urethane/urea polymeric flexible free standing films with two soft segments, polypropylene oxide and polybutadiene, can be induced by UV-irradiation. The ability to write/erase these 3D structures, in a controlled manner, is the main focus of this work. The imprinting of the wrinkled structures was accomplished by swelling in an appropriate solvent followed by drying the membranes after the cross-linking process and UV irradiation. The surface tailoring of the elastomeric membranes was imaged by optical microscopy, scanning electronic microscopy and by atomic force microscopy. To erase the wrinkled structures the elastomers were swollen. The swelling as well as the sol/gel fraction and the UV radiation were tuned in order to control the wrinkles characteristics. It was found that the wrinkles wavelength, in the order of microns (1±0,25μm), was stamped by the UV radiation intensity and exposure time while the wrinkles' amplitude, in the order of nanometers (150-450 nm), was highly dependent on the swelling and sol/gel fraction. A prototype for volatile organic compounds detection was developed taking advantage of the unique 3D micro/nano wrinkles features.
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Brunner, Pierre-Louis Marc. "Dispositifs optoélectroniques à base de semi-conducteurs organiques en couches minces." Thèse, 2015. http://hdl.handle.net/1866/16002.
Повний текст джерела