Abstract Chapter 1 provides an overview of this study and a literature review. Emphasis is put on the materials used, the different processes available to synthesize polymer-clay nanocomposites, analytical methods to characterize nanophase materials and on the impact of the nanophase on the final physical properties of polymer-clay nanocomposites. Chapter 2 discusses PE-clay nanocomposites which were synthesized using metallocene and Ni-diimine catalysts through in-situ polymerization. Morphological studies were carried out by XRD, SEM, EDX, and TEM to investigate the intercalation and exfoliation mechanism. Prior to its injection into the polymerization reactor, montmorillonite (MMT) was treated with triisobutyl aluminum and undecylenyl alcohol (UOH). Triisobutyl aluminum (TIBA) can react with hydroxyl groups on the surface of MMT and UOH is able to react with TIBA on the MMT surface. An alkoxy bond is generated by the reaction of the hydroxyl groups of UOH with the TIBA on the surface of MMT. A single site catalyst was then supported on the MMT/TIBA/UOH support, generating a MMT/TIBA/UOH/CAT system. The free vinyl groups of the surface UOH molecules can be copolymerized with ethylene, leading to the formation of chemical bonds between the MMT surface and polyethylene (PE). Ethylene polymerizations with the MMT/TIBA/UOH/CAT system were compared with ethylene polymerization with unsupported catalysts. The resulting PE-clay nanocomposites were analyzed with electronic and optical microscopes to confirm the nanophase distribution of MMT platelets in the polymer matrix. TEM images showed that the exfoliated MMT layers appeared as single layers or aggregated layers in the polyethylene matrix. After Soxhlet extraction with boiling 1,2,4-trichlorobenzene, the morphology of the residue particles remaining the thimble showed polymer fibrils stemming from the MMT surface, providing direct evidence of the chemical bonds between MMT surfaces and polymer matrix. Some residue particles also show PE-clay hybrid fibers between the particles. Through SEM/EDX analysis, it was confirmed that the fiber’s composition possessed silicone atoms together with carbon atoms. Chapter 3 discusses the results of in-situ polymerizations in gas-phase. The same catalyst systems and polymerization conditions discussed in Chapter 2 for slurry polymerization were applied to the gas-phase polymerization in order to investigate the particle fragmentation mechanism. After gas-phase polymerization at atmospheric pressure, the surface morphologies were investigated by SEM and TEM. In the case of the MMT/TIBA/UOH/Cp2ZrCl2 system, small particles (< 10m) were shattered from the larger particles (> 100 m) in the early stages of polymerization. After 24-hours of continuous polymerization, polymer fibrils growing from the inside of the MMT particles were observed by SEM. After further investigation with TEM, the cross-section profile of the particles showed curved bundles of MMT platelets, which illustrates exfoliation starting from the edges of the MMT particles. The MMT/TIBA/UOH/Ni-diimine system shows a different surface morphology after polymerization. In the early stages of the polymerization, polymer films were generated from the inside of the particles. After further polymerization, the MMT particles shattered and formed aggregates of PE-clay nanocomposites, similar to the ones proposed in the multigrain model. Chapter 4 discusses the copolymerization of ethylene and acrylonitrile. Ethylene/acrylonitrile copolymers were produced in the presence of a Ni-diimine/EASC catalyst system without the use of supports. Polymerizations of ethylene and acrylonitrile showed comparable activities in low concentrations of acrylonitrile. However, in higher concentrations, acrylonitrile induced a reductive elimination of the alkyl groups in the activated nickel-diimine catalyst. Conclusively, GPC analyses showed that acrylonitrile behaves as a chain transfer agent, showing reductive elimination of alkyl groups in the catalytic active center. The polymerization product morphology was analyzed by SEM and TEM. Polyacrylonitrile domains were observed in the polyethylene matrix and confirmed its nanosize distribution in the polyethylene matrix. DSC analysis of ethylene/acrylonitrile copolymers shows that an exothermic reaction takes place from 300 C to 370 C. This exotherm band detected by DSC can be related to the cyclization and aromatization of the nitrile groups of polyacrylonitrile. Through IR analysis of the ethylene and acrylonitrile polymer under high temperatures, this cyclization and aromatization was confirmed to be the cause of the decrease of the nitrile band (at 2244 cm-1) and increase of the vinyl bands (at 1640 cm-1). In addition, thermal treatment in DSC and successive XRD analysis showed the formation of the lamellar structures in the polyethylene matrix, reported as lamellar formation of polyacrylonitrile due to cyclization and aromatization of nitrile groups. The decomposition temperatures measured by TGA increased up to 50 C due to the presence of the nitrile groups in the polymer matrix. Tensile testing showed that the modulus increased, together with the yield strength and elongation. This phenomenon supports that strong interfacial interactions exist between the polyethylene matrix and polyacrylonitrile domains, as confirmed by TEM and IR analysis. Chapter 5 introduces the idea of acrylonitrile as a clay surface modifier. MMT was treated with acrylonitrile, using the same modification method of MMT that was applied in the MMT/TIBA/UOH/CAT system in Chapter 2. The nitrile groups in PE-MMT/TIBA/AN/CAT composites were confirmed at 2244 cm-1 by IR analysis. DSC analysis of PE-MMT/TIBA/AN/CAT showed that an exothermic reaction takes place from 300 C to 375 C. Successive DSC analysis with the same sample showed a new glass transition temperature band, induced by the reduction of polymer chain mobility. The basal diffraction band disappeared due to the exfoliation of MMT. Tensile tests showed an increase in modulus, without sacrificing the yield strength and elongation of PE-clay hybrid composites. Through these analyses, it was confirmed that strong interfacial forces exist between the polyethylene matrix and MMT layers in these PE-clay nanocomposites.

Abstract Chapter 1 provides an overview of this study and a literature review. Emphasis is put on the materials used, the different processes available to synthesize polymer-clay nanocomposites, analytical methods to characterize nanophase materials and on the impact of the nanophase on the final physical properties of polymer-clay nanocomposites. Chapter 2 discusses PE-clay nanocomposites which were synthesized using metallocene and Ni-diimine catalysts through in-situ polymerization. Morphological studies were carried out by XRD, SEM, EDX, and TEM to investigate the intercalation and exfoliation mechanism. Prior to its injection into the polymerization reactor, montmorillonite (MMT) was treated with triisobutyl aluminum and undecylenyl alcohol (UOH). Triisobutyl aluminum (TIBA) can react with hydroxyl groups on the surface of MMT and UOH is able to react with TIBA on the MMT surface. An alkoxy bond is generated by the reaction of the hydroxyl groups of UOH with the TIBA on the surface of MMT. A single site catalyst was then supported on the MMT/TIBA/UOH support, generating a MMT/TIBA/UOH/CAT system. The free vinyl groups of the surface UOH molecules can be copolymerized with ethylene, leading to the formation of chemical bonds between the MMT surface and polyethylene (PE). Ethylene polymerizations with the MMT/TIBA/UOH/CAT system were compared with ethylene polymerization with unsupported catalysts. The resulting PE-clay nanocomposites were analyzed with electronic and optical microscopes to confirm the nanophase distribution of MMT platelets in the polymer matrix. TEM images showed that the exfoliated MMT layers appeared as single layers or aggregated layers in the polyethylene matrix. After Soxhlet extraction with boiling 1,2,4-trichlorobenzene, the morphology of the residue particles remaining the thimble showed polymer fibrils stemming from the MMT surface, providing direct evidence of the chemical bonds between MMT surfaces and polymer matrix. Some residue particles also show PE-clay hybrid fibers between the particles. Through SEM/EDX analysis, it was confirmed that the fiber’s composition possessed silicone atoms together with carbon atoms. Chapter 3 discusses the results of in-situ polymerizations in gas-phase. The same catalyst systems and polymerization conditions discussed in Chapter 2 for slurry polymerization were applied to the gas-phase polymerization in order to investigate the particle fragmentation mechanism. After gas-phase polymerization at atmospheric pressure, the surface morphologies were investigated by SEM and TEM. In the case of the MMT/TIBA/UOH/Cp2ZrCl2 system, small particles (< 10m) were shattered from the larger particles (> 100 m) in the early stages of polymerization. After 24-hours of continuous polymerization, polymer fibrils growing from the inside of the MMT particles were observed by SEM. After further investigation with TEM, the cross-section profile of the particles showed curved bundles of MMT platelets, which illustrates exfoliation starting from the edges of the MMT particles. The MMT/TIBA/UOH/Ni-diimine system shows a different surface morphology after polymerization. In the early stages of the polymerization, polymer films were generated from the inside of the particles. After further polymerization, the MMT particles shattered and formed aggregates of PE-clay nanocomposites, similar to the ones proposed in the multigrain model. Chapter 4 discusses the copolymerization of ethylene and acrylonitrile. Ethylene/acrylonitrile copolymers were produced in the presence of a Ni-diimine/EASC catalyst system without the use of supports. Polymerizations of ethylene and acrylonitrile showed comparable activities in low concentrations of acrylonitrile. However, in higher concentrations, acrylonitrile induced a reductive elimination of the alkyl groups in the activated nickel-diimine catalyst. Conclusively, GPC analyses showed that acrylonitrile behaves as a chain transfer agent, showing reductive elimination of alkyl groups in the catalytic active center. The polymerization product morphology was analyzed by SEM and TEM. Polyacrylonitrile domains were observed in the polyethylene matrix and confirmed its nanosize distribution in the polyethylene matrix. DSC analysis of ethylene/acrylonitrile copolymers shows that an exothermic reaction takes place from 300 C to 370 C. This exotherm band detected by DSC can be related to the cyclization and aromatization of the nitrile groups of polyacrylonitrile. Through IR analysis of the ethylene and acrylonitrile polymer under high temperatures, this cyclization and aromatization was confirmed to be the cause of the decrease of the nitrile band (at 2244 cm-1) and increase of the vinyl bands (at 1640 cm-1). In addition, thermal treatment in DSC and successive XRD analysis showed the formation of the lamellar structures in the polyethylene matrix, reported as lamellar formation of polyacrylonitrile due to cyclization and aromatization of nitrile groups. The decomposition temperatures measured by TGA increased up to 50 C due to the presence of the nitrile groups in the polymer matrix. Tensile testing showed that the modulus increased, together with the yield strength and elongation. This phenomenon supports that strong interfacial interactions exist between the polyethylene matrix and polyacrylonitrile domains, as confirmed by TEM and IR analysis. Chapter 5 introduces the idea of acrylonitrile as a clay surface modifier. MMT was treated with acrylonitrile, using the same modification method of MMT that was applied in the MMT/TIBA/UOH/CAT system in Chapter 2. The nitrile groups in PE-MMT/TIBA/AN/CAT composites were confirmed at 2244 cm-1 by IR analysis. DSC analysis of PE-MMT/TIBA/AN/CAT showed that an exothermic reaction takes place from 300 C to 375 C. Successive DSC analysis with the same sample showed a new glass transition temperature band, induced by the reduction of polymer chain mobility. The basal diffraction band disappeared due to the exfoliation of MMT. Tensile tests showed an increase in modulus, without sacrificing the yield strength and elongation of PE-clay hybrid composites. Through these analyses, it was confirmed that strong interfacial forces exist between the polyethylene matrix and MMT layers in these PE-clay nanocomposites.

The objective of this study was to determine if the method of incorporation of a silicate layered nanoclay into a polymer matrix can affect the barrier properties of the pristine polymer in order to decrease the transport of volatile organic compounds (VOC) in indoor air. Building materials are a primary source for VOCs. These emissions are a probable cause of acute health effects and discomfort among occupants and are known to diminish productivity. The predicted concentrations of several of the VOCs emitted by structural insulated panels (SIP) are of concern with respect to health and comfort of occupants. The main issue related to the barrier membranes is the dispersion properties of the nanoclays in the polymer matrix, and the generation of a tortuous pathway that will decrease gas permeation. The tortuous pathway is created by a nanoclay filler, whose ideal exfoliated structure has high surface area, and high aspect ratio. By choosing the appropriate surfactants, the nanoclays can be modified to allow improved molecular interactions between the nanoclay and the polymer matrix. Several studies were performed in order to evaluate the dispersion properties of the nanoclay in the polymer matrix. Polymer/clay nanocomposites barrier membranes were generated via different synthesis methods. In the first study, barrier membranes were composed of a polyurethane, Estane ® 58315, and different nanoclays, Cloisite ® 10A, Cloisite ® 20A, Cloisite ® 30B. The interaction of the polyurethane and the different surfactants used to organically modify the nanoclay was evaluated. The dispersion of the clay platelets was analyzed by varying the pre-processing method; sonication vs stirring. The decrease in gas permeability results was enhanced by the effect of pre-processing via sonciation in comparison to plain stirring. These results also suggest that nanoclay platelets modified with alkylammonium groups with one tallow tail Cloisite ® 10A and Cloisite ® 30B, allow better dispersion and penetration of the polymer within the basal spacing of the nanoclays. Once the decrease in gas permeability was confirmed, the next challenge was to study and evaluate the performance of the polyurethane/clay nanocomposites barrier membranes in the determination of diffusivity coefficients for volatile organic compounds (VOCs). This was achieved via gravimetric sorption characterization. This method allowed for characterization of the sorption and desorption phenomena of VOC in barrier membranes. Barrier membranes pretreated with sonication demonstrated lower diffusivity coefficients than those only treated with stirring. At high clay loadings, 50 wt% of nanoclay in the polymer, the decrease in diffusivity coefficients for VOCs such as butanol and toluene, was found to be one order of magnitude. Other VOCs such as decane and tetradecane also showed a significant decrease in diffusivity coefficient. The results for VOC sorption studies suggest that there is some variability. In order to enhance the exfoliation of the clay, we decided to examine in situ polymerization of poly (n-butyl methacrylate) in the presence of nanoclay. In this study the clay wt% was kept at a low concentration of 1-5 wt%. The surface modification of natural montmorillonite, Cloisite ® Na+, was achieved via ion exchange, and the effect of pre-processing was also explored. The modification rendered a tethered group on the surface of the clay that was able to react with the monomer/oligomer chains and thus expand and exfoliate the clay platelets. Gas permeation data suggest that sonication also produced better barrier properties than its counterpart stirring. XRD diffractograms also confirmed exfoliation of the clay platelets in the poly (n-butyl methacrylate) polymer matrix. Thermogravimetric analysis (TGA) suggested that exfoliation of the clay platelets led to improved thermal stability by increasing the decomposition temperature of the membranes. A small increase in Tg also suggested restricted segmental chain motion within the clay platelets. Overall gas permeation decreased even at low clay content. Phenomenological models such as those of Cussler and Nielsen were used to model the experimental permeation results. These models suggest that although the aspect ratio of the clay platelets is within the specifications provided by the manufacturer, it does not reflect the ideal behavior of the models. The last step of this work was to achieve exfoliation of the modified nanoclay platelets via emulsion polymerization of poly (n-butyl methacrylate). The clay concentration in the emulsion was kept the same as in the in situ polymerization. DLS results suggest a uniform distribution of the polymer/clay nanocomposites particles in the emulsion. Permeation data indicated higher permeation values than the in situ method of synthesis of the nanocomposite membranes. This led us to explore the use of glassy co-polymer of poly(n-butyl methacrylate)-poly(methyl methacrylate) as the matrix. The addition of a more glassy component in the polymer matrix led to improved barrier properties of the nanocomposite membranes. As expected, the copolymer had a higher Tg than the PMMA polymer. Analysis via phenomenological models, also suggested that the chemistry of the co-polymer played an important role in decreasing gas permeability within the polymer/clay nanocomposite membranes, although the effect of the glassy component in the matrix was not quantified by the phenomenological models. / Ph. D.

Orientador: Maria Isabel Felisberti / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-16T00:31:14Z (GMT). No. of bitstreams: 1 Carvalho_FabianaPiresde_D.pdf: 10993804 bytes, checksum: d95821798b6ae5ce1dd39dc3037a996e (MD5) Previous issue date: 2010 / Resumo:Neste trabalho foram preparadas e caracterizadas blendas de poli(metacrilato de metila), PMMA e poli[acrilonitrila-g-(etileno-co-propileno-co-dieno)-g-estireno], AES. O AES é um polímero amorfo e um material complexo, composto de uma mistura de poli(etileno-co-propileno-co-2-etilideno-5-norboneno) (EPDM), poli(estireno-coacrilonitrila) (SAN), e copolímero de enxertia EPDM-g-SAN. As blendas PMMA-AES foram obtidas por polimerização in situ, tendo-se como variáveis o solvente, agitação e atmosfera inerte, a fim de avaliar a influência destas sobre as propriedades estruturais e morfológicas das blendas. As blendas foram caracterizadas por espectroscopia infravermelho (IV), ressonância magnética nuclear de C (RMN de C), microscopia eletrônica de varredura (SEM), microscopia eletrônica de transmissão (TEM), análise dinâmico-mecânica (DMA) e resistência ao impacto. Os resultados mostraram que as blendas são imiscíveis apresentando uma morfologia complexa de domínios elastoméricos dispersos em uma matriz vítrea, dependente das condições de polimerização. Em algumas blendas, uma fração de PMMA encontra-se incluso na fase elastómerica, sugerindo uma morfologia tipo core shell ou tipo salame. Porém, essa morfologia complexa é afetada após o processo de injeção, devido ao efeito de temperatura e de cisalhamento. Extração seletiva e análise por espectroscopia infravermelho dos componentes das blendas mostraram que ocorre enxertia e/ou reticulação durante a polimerização. A sindiotaticidade do PMMA obtido em presença de AES aumenta com a quantidade de AES na blenda, devido às possíveis interações entre os grupos carbonilas do PMMA e os grupos nitrilas e fenilas da fase SAN. As blendas PMMA-AES apresentam propriedades mecânicas dependentes do teor de AES, sendo a resistência ao impacto das blendas superiores a do PMMA puro. Ensaios de envelhecimento fotoquímico acelerado mostraram que as blendas PMMA-AES apresentam queda na resistência ao impacto após envelhecimento / Abstract: In this work, blends of the poly(methyl methacrylate), PMMA, and the poly[acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene], AES, were prepared. AES is a complex mixture of poly(styrene-co-acrylonitrile), SAN, and poly(ethylene-copropylene-co-diene), EPDM, and the graft copolymer EPDM-g-SAN. Blends PMMA-AES were obtained by polymerization in situ, varying the solvent, the agitation and the inert atmosphere in order to evaluate their influence on the morphological and structural properties of the blends. The blends were characterized by infrared spectroscopy (FTIR), carbon-13 nuclear magnetic resonance (C NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA) and Izod impact resistance test. The results showed that the PMMA-AES blends are immiscible and present a complex morphology. The morphology of some PMMA-AES blends is made up of an elastomeric dispersed phase in the glassy matrix, with inclusion of the matrix in the EPDM domains, suggesting core shell or salami morphology. However, this morphology is affected by the moulding injection process, due the temperature and shear effects. The selective extraction of the blends¿ components and the infrared spectroscopy showed that crosslinked and/or grafting reactions occur on EPDM chains during MMA polymerization. The syndiotactic PMMA obtained in the presence of AES increases with the amount of AES, due to the possible interaction among the carbonyl groups of PMMA and the nitrile or phenyl groups of SAN copolymer. The mechanical properties of the blends were influenced by the composition of the blend and the impact strength of the blends is superior to near PMMA. Photochemical aging tests showed that PMMA-AES blends presented decrease in the impact strength after aging / Doutorado / Físico-Química / Doutor em Ciências

Orientador: Maria Isabel Felisberti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química. / Made available in DSpace on 2018-08-19T11:49:08Z (GMT). No. of bitstreams: 1 Cocco_DanielRotella_M.pdf: 5124890 bytes, checksum: 11103bdc5dccd20252a90d83a5a6ba95 (MD5) Previous issue date: 2011 / Resumo: Neste trabalho foram preparadas e caracterizadas blendas de poli(metacrilato de metila), PMMA, e poli[acrilonitrila-co-acrilato de butila], ASA. O ASA é um polímero amorfo e constituído de uma mistura de poli(acrilato de butila) (PBA) e poli(estireno-co-acrilonitrila) (SAN). As blendas PMMA-ASA foram obtidas por polimerização in situ, tendo sido estudada a influência do agente de transferência de cadeia, da agitação e da atmosfera inerte sobre as propriedades estruturais e morfológicas das blendas. As blendas foram caracterizadas por cromatografia de permeação em gel (GPC), espectroscopia infravermelho (IV), análise termogravimétrica (TGA), ressonância magnética nuclear de C (RMN de C), análise dinâmico-mecânica (DMA), microscopia eletrônica de varredura (SEM), microscopia eletrônica de transmissão (TEM), e resistência ao impacto e tração. Os resultados mostraram que as blendas são imiscíveis apresentando uma morfologia complexa de domínios elastoméricos dispersos em uma matriz vítrea, dependente das condições de polimerização. Em algumas blendas, uma fração de PMMA encontra-se possivelmente inclusa na fase elastómerica, sugerindo uma morfologia tipo core shell ou tipo salame. Porém, essa morfologia complexa é afetada após o processo de injeção para algumas blendas, devido ao efeito de temperatura e de cisalhamento. Extração seletiva e análise por espectroscopia infravermelho dos componentes das blendas mostraram que ocorre enxertia e/ou reticulação durante a polimerização. A sindiotaticidade do PMMA obtido em presença de ASA aumenta com a quantidade de ASA na blenda, devido às possíveis interações entre os grupos carbonilas do PMMA e os grupos nitrilas e fenilas da fase SAN. As blendas PMMA-ASA apresentam propriedades mecânicas dependentes do teor de ASA e das condições de preparo, sendo a resistência ao impacto das blendas superiores à do PMMA puro / Abstract: In this work, blends of the poly(methyl methacrylate), PMMA, and the poly[acrylonitrile-co-styrene-co-butyl acrylate], ASA, were prepared. ASA is a complex mixture of poly(styrene-co-acrylonitrile), SAN, and poly(butyl acrylate), PBA. Blends PMMA-ASA were obtained by polymerization in situ, and the influence of a chain transfer agent, stirring and the inert atmosphere on the morphological and structural properties of the blends was studied. The blends were characterized by gel permeation chromatography (GPC), infrared spectroscopy (FTIR), C nuclear magnetic resonance ( C NMR), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), lzod impact resistance test and tensile tests. The results showed that the PMMA-ASA blends are immiscible and present a complex morphology. The morphology of some PMMA-ASA blends is made up of an elastomeric dispersed phase in the glassy matrix, with a possible inclusion of the matrix in the elastomeric domains, suggesting core shell or salami morphology. However, this morphology is affected by the moulding injection process, for some blend compositions, due the temperature and shear effects. The selective extraction of the blends components and the infrared spectroscopy showed that crosslinked and/or grafting reactions occur on ASA chains during MMA polymerization. The syndiotacticity of PMMA obtained in the presence of ASA increases with the amount of ASA, due to the possible interaction among the carbonyl groups of PMMA and the nitrile or phenyl groups of SAN copolymer. The mechanical properties of the blends were influenced by the composition of the blend and conditions of polymerization, and the impact strength of the blends is superior to neat PMMA / Mestrado / Físico-Química / Mestre em Química

Polymer electrochromism on PEDOT coated fibres was successfully achieved. The electrochromic property of the PEDOT polymer is an excellent property. This feature gives way to many more research works at present and in the future also. The electrochromic property of the PEDOT polymer is utilized in this thesis work to design an electrochromic display pixel. The polymer coating over the fibres were obtained by using In-situ polymerization technique. The coated-fibres were used to design a display-pixel. Electrochemistry is performed successfully on the designed pixel to study electrochromism over the pixels. An electrochemical fibre transistor is designed successfully using the polymer coated fibres. / Polymer Electrochromism on PEDOT coated fibres

Luminescent emission of non-fully conjugated homopolymers was successfully demonstrated as light emitting diodes (LEDs) in this research. Coil-like heterocyclic aromatic poly[2,2-(2,5-dialkyloxyphenylene)-4-4¡¦-hexafluoroisopropanebibenzoxazo- les] (6F-PBO-CnOTpA, with n = 10, 15, and 20) was synthesized, and polymer composites of 6F-PBO-CnOTpA was in-situ synthesized with acidified multi-wall carbon nanotube (MWNT- COOH). The non-fully conjugated coil-like heterocyclic aromatic homopolymer was synthesized by reacting 2,2,bis-(3-amino-4-hydroxy[henyl]-hexafluoropropane with 2,5-dialkyloxyterephthalic acid (CnOTpA) for 6F-PBO-CnOTpA, with n = 10, 15, and 20. In addition, MWNT was acidified for connecting the carboxylic group (-COOH) to reduce its aspect ratio and entropy induced aggregation. MWNT-COOH was analyzed using elemental analysis (EA) and viscometry to validate the effects of acidification period. The EA result seemed to suggest that the oxygen content increased, and the carbon and the hydrogen contents decreased with acidification period. The inherent viscosity (£binh) decreased according to acidification period suggesting that the aspect ratio was indeed decreased. A hole transport layer of PEDOT¡GPSS was applied for multi-layer LEDs,. The LEDs all showed a threshold voltage about 4 V also for the composites of 6F-PBO-CnOTpA in-situ polymerized with MWNT-COOH. The 6F-PBO-CnOTpA LEDs with and without MWNT-COOH showed an electroluminescence emission range of 400 to 750 nm.

Polymer-clay nanocomposites have received a lot of attention because of outstanding improvements in properties when compared with neat polymeric materials. The aim of this study was to prepare epoxy-clay nanocomposites by mixing organically modified montmorillonite with an epoxy resin and to investigate the effects of clay content on the mechanical, thermal and flammability properties of the resultant nanocomposites. The production of the epoxy-clay nanocomposites was accomplished by in-situ polymerization. In the nanocomposite synthesis, organically modified clay content was varied from 1 wt.% to 9 wt.%. Araldite LY556 epoxy resin, Aradur 918 anhydride hardener, and DY070 imidazole type accelerator were used in the epoxy system. Closite 30B, an organoclay modified with methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium chloride (MT2EtOH), was used as the clay material. X-ray diffraction results showed that d-spacing between the platelets of organoclay increased from 1.80 nm to 4.4 nm. The microstructures of nanocomposites were investigated by scanning electron microscopy (SEM). The SEM micrographs indicated that at 1 wt.% clay loading, no clay aggregates were observed. On the other hand, beyond 1 wt.% clay loading, formation of clay agglomerations was observed. Tensile strength and tensile strain values of nanocomposites decreased with clay loading. The tensile strength value of neat epoxy resin decreased from 55 MPa to 29 MPa with 9 % clay loading. On the other hand, Young&amp / #8217 / s modulus increased with clay content and a maximum value was obtained at 5 wt. % clay loading. At 9 % clay loading, Young&amp / #8217 / s modulus value was 26 % higher than that of the neat epoxy resin. Impact strength property had a minimum value at 7 wt. % clay content. Flexural strength and flexural strain at break property behaved in a similar trend. They had a minimum value at 5 % clay loading. At this clay loading, flexural strength value became approximately 43 % lower compared to the flexural strength of the neat epoxy resin. On the other hand, at 9 wt.% clay loading flexural modulus value increased approximately 48 % compared to the pure epoxy resin. Up to 7 wt.% clay ratio, initial decomposition temperature of epoxy resin was slightly improved. Also, according to TGA results, amount of char formation increased with clay loading. DSC results indicate that Tg of the cured nanocomposite resins decreased from 147 oC to 129 oC with 9 wt. % clay loading. The flammability of neat epoxy resin was not significantly affected with Cloisite 30B addition.

<p>Polymer electrochromism on PEDOT coated fibres was successfully achieved. The electrochromic property of the PEDOT polymer is an excellent property. This feature gives way to many more research works at present and in the future also. The electrochromic property of the PEDOT polymer is utilized in this thesis work to design an electrochromic display pixel.</p><p> </p><p>The polymer coating over the fibres were obtained by using In-situ polymerization technique. The coated-fibres were used to design a display-pixel. Electrochemistry is performed successfully on the designed pixel to study electrochromism over the pixels. An electrochemical fibre transistor is designed successfully using the polymer coated fibres.</p> / Polymer Electrochromism on PEDOT coated fibres

This study was conducted to investigate the effects of organoclay type and concentration on the nanocomposites synthesized by &ldquo / In-Situ Polymerization&rdquo / and &ldquo / Prepolymerization&rdquo / methods. In-Situ Polymerization Method was in fact a new route which consisted of dispersing the monomers / propylene glycol, maleic anhydride and o-phthalic anhydride into the galleries of montmorillonite followed by subsequent polymerization. The Prepolymerization Method involved the addition of montmorillonite to the previously synthesized unsaturated polyester. As the first step, all the compositions were prepared by Cloisite 30B, and then for comparison of clay type, nanocomposites containing 3 wt.% of Cloisite 15A and Cloisite 25A were also synthesized. The efficiency of the two methods were compared with regards to their structural, thermal and mechanical properties. According to the results of XRD analysis, in both methods, maximum intercalation was observed when Cloisite 30B was used. An exfoliated structure was obtained in the Prepolymerization Method at 3 wt. % Cloisite 30B content. In all clay types, the increase in the d-spacings of the organoclays was higher when the Prepolymerization Method was applied. With Cloisite 30B, maximum improvement in the impact strength was obtained at 3 wt. % organoclay loading and the In-Situ Method yielded better results leading to a 77% increase in the impact strength at this organoclay loading. Among the organoclay types, Cloisite 15A was found to give rise to maximum increase in the impact strength. With the Prepolymerization Method higher improvement in flexural strength and flexural modulus was obtained owing to the lower styrene content in the crosslinking medium. The elongation at break values followed a decreasing trend with increasing clay content but did not show any significant difference when the clay types were compared.