Hybrid organic-inorganic materials represent a new class of materials having scientific and technological potential. In this thesis, Polyhedral Oligomeric Silsesquioxanes (POSS) are used as an inorganic building block which has been tethered to an organic polymer. POSS are silica precusors, having a well defined silsesquioxane cental core surrounded by an organic periphery which makes them compatible with monomers and possibly polymers. The objectives of this study are to (1) study the basic structures of POSS homopolymers, (2) to incorporate POSS building blocks by a bottomup approach into polymer chains and study the resulting morphologies, and (3) to study the thin film behavior of POSS block copolymers. PMA and styryl POSS homopolymers of different peripheries were synthesized by ATRP and mass spectrometry studies were carried out by MALDI-TOF and ESI. PMA POSS chains undergo a number of fragmentations while styrly POSS chains have a relatively robust backbone. Poly(ethylene-butylene-b-MAPOSS), AB type copolymers and poly(MAPOSS-b-styrene-b-MAPOSS), ABA type copolymers were synthesized by a combination of anionic and ATRP polymerization. Spheres, inverse cylinders, lamellar and crystalline lamellar morphologies were observed for the poly(ethylene-butylene-b- MAPOSS) copolymers. In the poly(MAPOSS-b-styrene-b-MAPOSS) copolymers, cylindrical, lamellar and perforated lamellar morphologies were obtained. Beyond the interaction parameter (χ), total degree of polymerization (N) and volume fraction (f), the conformational asymmetry (ε) also plays an important role in determining the morphology of these block copolymer. Crystallization of the POSS phase and better thermal properties were observed in the both block copolymers. Thin film studies of poly(MAPOSS-b-styrene-b-MAPOSS) copolymers showed that the microdomains can be oriented either parallel or perpendicular to the substrate depending upon the film thickness, morphology and relative volume fractions of the connecting blocks. By removal of the organic phase, ordered mesoporous low dielectric constant silica films were obtained. These hybrid block copolymers are a potential candidate for nanopatterning applications.

Polyedrisk oligomer silsesquioxane (POSS) är molekyler som har en inorganisk ryggrad med organiska grupper fa ̈sta utan på. Själva kåren har en bur liknande form och har en hög termisk stabilitet tack vare kisel (Si) och syre (O) som den består av. Det organiska grupperna som kan fästas på kåren kan variera för att få en molekyl som är anpassad för det material den ska blandas in i, tillexempel polyvinylklorid (PVC). POSS molekylerna kan blandas in i material antigen fysiskt eller kemiskt beroende på vilka organiska grupper molekylen består av. Tack vare den termiska stabiliteten POSS är på en intressant molekyl att använda som ett alternativt flamskyddsmedel till existerande flamskyddsmedel.  Det olika POSS materialen var producerade med lite olika reaktions parametrar och var gjorda av Funzionano AS i Norge, Porsgrunn. Materialet har bevarat olika lång tid men det olika POSS materialen har också olika funktionella grupper. Provet med namn SF458 211122 var också adderat till PVC materialet för att se om det påverkade PVC:s termiska egenskaper.  Syftet med detta master arbete är att kolla om tiden proverna bevaras, olika funktionella grupper och om olika reaktions parametrar kommer påverka det termiska egenskaperna. Dessa parametrar utforskas genom att använda analys instrumenten TGA/DSC och DSC. Men också för att se om POSS förbättrar PVC:s termiska egenskaper.  Resultaten visar att 3 av det 4 olika SF458 proverna hade liknande glasstransaktions temperaturer (Tg) som är runt 27 °C även om det förvarats olika lång tid. 1 av det 4 olika SF458 hade högre Tg vilket kan bero p ̊a att den syntesen hade andra reaktions förhållanden i sista reaktions steget bland annat. Smältpunkten och mängden prov kvar efter TGA analyserna kan påverkas av förvaringstiden eller reaktions förhållandena. För att få fram vad som påverkar vad måste mer forskning göras. / Polyhedral oligomeric silsesquioxane (POSS) are molecules with an inorganic backbone which has organics groups attached to the backbone. The backbone is like a cage and the functional groups are arms that goes out from the cage. The inorganic backbone does so the molecule has high thermal stability and the functional groups make it possible to tailor the molecule so it can be easier to physical or chemical blend it into a material, like thermoplastics. The thermal properties of POSS make it to an interesting alternative as a flame retardant since it is also not has hazardous as other common flame retardants.  The different POSS material have been synthesised with some different reaction parameters and were prepared by Funzionano AS in Norway, Porsgrunn. The material have been stored for different times but also the cage have different functional groups attached to it. POSS named SF458 211122 were also physically incorporated to polyvinyl chloride (PVC) to see if it have any effect on the thermal properties.  The aim of the study is to see if the time of storage, different functional groups and different synthesis parameters affect the thermal properties of the POSS material by using DSC and TGA/DSC instruments. But also to see if the thermal properties of PVC is improved when POSS is physically added.  The results showed that 3 of 4 of the different SF458 samples had similar glass transition temperatures (Tg), around 27 °C so the time of storage does not affect that property. Since 1 of the 4 samples had a higher Tg is probably due to other synthesis conditions. The affect in melting point and amount of residue can be effected by either the time of storage or the parameters for the synthesis. So, further research needs to be done.

<p>Effects of a nanometer-size, reactive polyhedral oligomeric silsesquioxane (POSS) on a thermoset’s polymerization kinetics and dielectric relaxation have been investigated by using differential scanning calorimetry (DSC) and dielectric spectroscopy. Four amines, hexylamine (HA), ethylene diamine (EDA), isophorone diamine (IPDA), and diethylene triamine (DETA) were used to crosslink epoxy resin DGEBA and a multi functionalized -glycidyl POSS. The polymers formed ranged from POSS-free to POSS-only network structure, while maintaining an equal ratio of reactive groups.</p> <p>Calorimetric studies of stoichiometric DETA and IPDA samples performed by ramp-heating showed that the polymerization kinetics increased with low POSS content, but progressively decreased upon further addition, and the POSS-only mixtures reacted the slowest. The same pattern of changes in the rate of polymerization was observed by isothermal polymerization of the DETA mixtures. The results have been interpreted based on changes in viscosity and diffusion coefficients according to the Stokes-Einstein and Smoluchowski equations. Furthermore, isothermal polymerization of stoichiometric DETA and EDA samples showed that the extent of reaction increased with POSS, indicating that it might be easier to form a higher crosslinked thermoset with higher amounts of POSS.</p> <p>Non-isothermal polymerization of POSS-IPDA mixtures was also investigated under off-stoichiometric conditions. Unlike the reaction mechanisms of non-stoichiometric DGEBA-IPDA mixtures, a significant difference in reactivity of primary and secondary amines in the POSS-IPDA reaction was not observed.</p> <p>Dielectric relaxation studies were performed in real time during polymerization. The distribution of relaxation rates increased with an increase in POSS, and the duration of polymerization required to reach a specific relaxation time increased. Furthermore, the time at which the dielectric loss minimum and peak occurred increased with POSS, however, when only POSS was reacted with the amine, an <em>a</em>-relaxation peak was not observed. A frequency-dependent increase in permittivity during polymerization was observed with the POSS-only EDA, DETA, and HA samples, and a corresponding change in the loss was not detected. It was attributed to a structure-dependent increase in interfacial polarization.</p> <p>Although not related to the polymerization study, work done on the residual entropy of glasses is included here. To help resolve the controversy of the residual entropy of glassy materials, specific heat data taken from the literature were analyzed. The changes in entropy of a glass on cooling and heating paths were determined, and it was found that the upper and lower limits of entropy differed by no more than 2 %. This showed that although the thermodynamic path through the glass transition is irreversible, this irreversibility has a negligibly small effect on determining the entropy.</p> / Master of Applied Science (MASc)

Langmuir-monolayer formation at the air/water interface (A/W) can be achieved by spreading amphiphilic molecules on a liquid subphase and compressing them into an ordered arrangement. The use of the Langmuir-Blodgett technique (LB) to prepare ultra thin films on solid surfaces from monolayers at A/W has considerable utility for studying surface interactions. In particular, the phase behavior of polyhedral oligomeric silsesquioxanes (POSS) was examined using a combination of LB and Brewster angle microscopy (BAM).Polymer fillers have been shown to reduce the cost and often improve the properties of high performance polymer composites. The utility of POSS as a potential nanofiller in blends with polymers such as poly(dimethylsiloxane) (PDMS) and poly(vinylacetate) (PVAc) was explored using surface pressure-area per monomer isotherms (P-A) and BAM. Substantial morphological differences are seen between polymer blends with heptasubstituted trisilanol-POSS and fully condensed octasubstituted-POSS due to differences in subphase affinity.Several poly(1-alkene-alt-maleic anhydride) (PXcMA) polymers were studied at both the gas/liquid interface as Langmuir films and at the gas/solid interface as Langmuir-Blodgett thin films on silicon substrates. A 0.01 M HCl solution (pH~2) was used during film deposition to ensure the carboxylic acids were fully protonated. The PXcMA polymers included X=1-hexene, 1-octene, 1-decene, and 1-octadecene (represented as PHcMA, POcMA, PDcMA, and PODcMA respectively). The P-A isotherms of these polymers were consistent with those obtained previously.1Tensiometry was used to determine the critical micelle concentrations (c.m.c.) of variable molar mass poly(dimethylsiloxane-b-(3-cyanopropyl)methylsiloxane-b-dimethylsiloxane) (PDMS-PCPMS-PDMS) triblock copolymers and a poly(dimethylsiloxane-b-2-ethyl-2-oxazoline) diblock copolymer. Dynamic light scattering (DLS) corroborated interfacial tension results. The polymers exhibited well-defined temperature-independent c.m.c.'s. These measurements ensured that the synthesis of cobalt nanoparticles for biocompatible magnetic fluids occurred above the c.m.c. / Master of Science

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-02-21T18:54:24Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Viviane Jandira Van Haandel.pdf: 1227295 bytes, checksum: 9d7e4a5d542b374919d27cacb32e328b (MD5) / Made available in DSpace on 2018-02-21T18:54:24Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Viviane Jandira Van Haandel.pdf: 1227295 bytes, checksum: 9d7e4a5d542b374919d27cacb32e328b (MD5) Previous issue date: 2017-11-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho descreve a preparação e caracterização de um silsesquioxano funcionalizado com imidazol com objetivo de aplicação como adsorvente para íons metálicos de interesse ambiental, utilizando como síntese o processo sol-gel cuja rota vem sendo muito utilizada devido as inúmeras vantagens. A primeira etapa consistiu na reação entre tetraetilortosilicato e 3-cloropropiltrimetóxisilano, através do processo Sol-Gel, para a formação do material designado como TEOS/CPTMS. Em seguida promoveu-se a incorporação do imidazol a rede de sílica, obtendo-se o cloreto de npropil imidazol silsesquioxano. O material obtido foi caracterizado pelas técnicas de Espectroscopia de na região do infravermelho com transformada de Fourier (FTIR), Espectroscopia por ressonância magnética nuclear de 29Si e 13C (RMN 29Si e 13C), Difratometria de Raios X (DRX), Espectroscopia de espalhamento Ramam, Análise de área de superfície por isortermas Brunauer, Emmett e Taller (BET). A capacidade de troca do material foi de 2,87 mmol g-1. Devido a sua boa capacidade de troca, o material foi utilizado na adsorção de íons metálico, de interesse ambiental, em meio aquoso. O tempo para atingir o equilíbrio no processo de adsorção-dessorção foi de 8 horas, o íon Cu+2 e Ni+2 adsorvem melhor em pH 4, já o processo de adsorção do íon Cd+2 aparentemente não tem influência do pH do meio. O material sintetizado adsorveu 3,60 mmol de Cu+2, 2,68 mmol de Cd+2 e 1,10 mmol de Ni+2 por grama de material. O modelo que obteve maior concordância com os resultados experimentais foi o de modelo de Langmuir comparado ao modelo de Freudlich. / The present work describes the preparation and characterization of an imidazole functionalized silsesquioxane with the objective of applying as metallic ion adsorptive for environmental interest, using as a synthesis the sol-gel process whose route has been widely used due to the numerous advantages. The first step consisted of the reaction between tetraethylorthosilicate and 3-chloropropyltrimethoxysilane, through the sol-gel process, for the formation of the material designated as TEOS / CPTMS. The incorporation of the imidazole into the silica network was promoted, giving the npropyl imidazole silsesquioxane chloride. The obtained material was found in the techniques of Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (29Si and 13C NMR), X-ray diffractometry (XRD), Ramam scattering spectroscopy, Surface area analysis by Brunauer, Emmett and Taller (BET) isortermas. The material exchange capacity of was 2.87 mmol g-1. Due to its good exchangeability, the material was used in the adsorption of metallic ions, of environmental interest, in aqueous medium. The time to equilibrium in the adsorptiondesorption process of 8 hours, the Cu+2 and Ni+2 ion adsorb better at pH 4, since the adsorption process of the Cd+2 ion apparently does not influence the pH of the medium. The synthesized material adsorbed 3.60 mmol Cu+2, 2.68 mmol Cd+2 and 1.10 mmol Ni+2 per grama of material. The model that obtained the highest agreement with the experimental results was the model of Langmuir compared to the model of Freudlich.

Traditional fluorosilicones contain a siloxane backbone and pendant fluorinated group leading to low temperature ductility and excellent thermal stability. However, acidic or basic catalysts can reduce the thermal stability from a potential 350 °C to 150 °C. The predominant decomposition mechanism is through chain scission and it is hypothesized that preventing this will result in polymers with higher thermal stability. Three approaches were taken to prevent chain scission. First, a series of hybrid fluorosilicones based on (trifluorovinyl)benzene were synthesized through condensation polymerization with initial decomposition temperatures of approximately 240 °C. These were compared to similar aromatic polyethers and removal of the ether oxygen lowered the initial decomposition temperature by approximately 190 °C demonstrating the importance of this oxygen to the stability of polyethers. Second, reverse fluorosilicone (fluorinated backbone and pendant siloxane) terpolymers of chlorotrifluoroethylene (CTFE), vinyl acetate (VAc) and methacryloxypropyl-terminated polydimethylsiloxane (PDMSMA) were synthesized in supercritical CO2 (scCO2) or by emulsion polymerization. Chain scission was prevented as initial decomposition occurred between 231 and 278 °C. In both the emulsion and scCO2 cases, VAc was essential in facilitating cross-propagation between CTFE and PDMSMA and the branching was similar suggesting polymerization media does not affect polymer structure. Emulsion-based polymers had higher molar masses and thermal stability whereas comparable scCO2 polymers had higher yields and incorporated more PDMSMA. Third, a series of homo-, co-, and terpolymers of CTFE, VAc and methacryloxypropyl-terminated silsesquioxane (POSSMA) were synthesized representing the first synthesis of POSSMA containing polymers in scCO2 and demonstrating reverse fluorosilicones can be synthesized without VAc. Chain scission was prevented as initial decomposition occurred from 244 to 296 °C with thermal stability increasing with CTFE content to a limit. Decomposition of the polymers was examined and mechanism elucidated. In air, the copolymers give 40 to 47 wt% char since the silsesquioxane oxidizes to SiO2 while in N2, no residue is seen. In contrast, the terpolymers give a carbonaceous residue of approximately 20 wt% in N2. The flammability and surface properties of the polymers were examined with the terpolymers having flammability similar to p(CTFE) and surface properties comparable to p(POSSMA) giving a low-flammability, hydrophobic polymer.

Traditional fluorosilicones contain a siloxane backbone and pendant fluorinated group leading to low temperature ductility and excellent thermal stability. However, acidic or basic catalysts can reduce the thermal stability from a potential 350 °C to 150 °C. The predominant decomposition mechanism is through chain scission and it is hypothesized that preventing this will result in polymers with higher thermal stability. Three approaches were taken to prevent chain scission. First, a series of hybrid fluorosilicones based on (trifluorovinyl)benzene were synthesized through condensation polymerization with initial decomposition temperatures of approximately 240 °C. These were compared to similar aromatic polyethers and removal of the ether oxygen lowered the initial decomposition temperature by approximately 190 °C demonstrating the importance of this oxygen to the stability of polyethers. Second, reverse fluorosilicone (fluorinated backbone and pendant siloxane) terpolymers of chlorotrifluoroethylene (CTFE), vinyl acetate (VAc) and methacryloxypropyl-terminated polydimethylsiloxane (PDMSMA) were synthesized in supercritical CO2 (scCO2) or by emulsion polymerization. Chain scission was prevented as initial decomposition occurred between 231 and 278 °C. In both the emulsion and scCO2 cases, VAc was essential in facilitating cross-propagation between CTFE and PDMSMA and the branching was similar suggesting polymerization media does not affect polymer structure. Emulsion-based polymers had higher molar masses and thermal stability whereas comparable scCO2 polymers had higher yields and incorporated more PDMSMA. Third, a series of homo-, co-, and terpolymers of CTFE, VAc and methacryloxypropyl-terminated silsesquioxane (POSSMA) were synthesized representing the first synthesis of POSSMA containing polymers in scCO2 and demonstrating reverse fluorosilicones can be synthesized without VAc. Chain scission was prevented as initial decomposition occurred from 244 to 296 °C with thermal stability increasing with CTFE content to a limit. Decomposition of the polymers was examined and mechanism elucidated. In air, the copolymers give 40 to 47 wt% char since the silsesquioxane oxidizes to SiO2 while in N2, no residue is seen. In contrast, the terpolymers give a carbonaceous residue of approximately 20 wt% in N2. The flammability and surface properties of the polymers were examined with the terpolymers having flammability similar to p(CTFE) and surface properties comparable to p(POSSMA) giving a low-flammability, hydrophobic polymer.

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-20Bitstream added on 2014-06-13T18:53:39Z : No. of bitstreams: 1 soares_la_me_ilha.pdf: 1532013 bytes, checksum: 0f4004d265a97a7015b084d2b64eb7b7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho apresenta a preparação de um silsesquioxano nanoestruturado, o cloropropilsilsesquioxano (S) que foi organofuncionalizado com os seguintes agentes modificadores: 4-amino-3-hidrazinico-5-mercapto-1,2,4-triazol (Purpald®) e o 4-amino-5-4(piridil)-4H-1,2,4-triazol-3-tiol (APTT), os materiais obtidos dessa funcionalização foram descritos como SP e SA, respectivamente. Os materiais SP e SA foram caracterizados por diversas técnicas espectroscópicas: Espectroscopia na região do infravermelho (FT-IR), Ressonância magnética nuclear 29Si e 13C no estado sólido (RMN), Difração de Raios- X (DRX), Espectroscopia de Energia Dispersiva de Raios X (EDX), Termogravimetria e Análise Térmica Diferencial (TG – DTA). Após a devida caracterização, realizaram-se estudos de adsorção de íons metálicos (Cu2+, Cd2+ e Ni2+) nos sítios ativos do SA, porém, curiosamente não se observou a mesma capacidade de sorção pelo SP. Diferentes meios foram estudados no processo de adsorção dos íons metálicos supracitados: aquoso, etanólico 99% e etanólico 42%, determinando-se o tempo de equilíbrio de adsorção, que para ambos os meios e metais esse tempo máximo foi em média 35 min. Determinado o tempo de equilíbrio de adsorção dos íons metálicos em cada sistema, determinou-se a capacidade específica de sorção (Nfmax) através de isotermas de adsorção. Para o Cu2+, os valores de Nf foram: meio aquoso (3,09 × 10-4 mol g-1), etanólico 42% (1,03 × 10-4 mol g-1) e etanólico 99% (1,86 × 10-4 mol g-1), com concentrações de íons Cu2+ variando de 1,74 a 29,64 mol L-1. Os valores encontrados para o Ni2+ foram: em meio aquoso (2,11 × 10-4 mol g-1), etanólico 42% (0,97 × 10-4 mol g-1) e etanólico 99% (1,05 × 10-4 mol g-1), com concentrações de íons Ni2+ variando de 2,25 a 33,18 mol L-1. Para os íons cádmio não foram... / This work presents the preparation of a nanostructured silsesquioxane, the cloropropilsilsesquioxano (S) that was organofunctionalised with the following modifying agents: 4-amino-3-hydrazino 5 - mercapto 1,2,4 triazole (Purpald ®) and 4- amino-5-4 (pyridyl)-4H-1,2,4-triazole-3-thiol (APTT), the materials obtained of the functionalization were described as SP and SA, respectively. The materials SA and SP were characterized by various spectroscopic techniques such as spectroscopy in the region of infrared (FTIR), nuclear magnetic resonance 29Si and 13C solid-state (NMR), X-ray diffraction (XRD), Energy Dispersive Spectroscopy Rays (EDS), Thermogravimetry and Differential Thermal Analysis (TG - DTA). After proper characterization, were carried studies on adsorption of metallic ions such as Cu2+, Ni2+ and Cd2+ in the active sites of SA, but curiously did not observe the same sorption capacity of the SP. Different methods were studied in the adsorption of metal ions above: aqueous, 99% ethanolic and 42% ethanolic, determining the adsorption equilibrium time, which for both means and metals the maximum time averaged 35 min. After determining the adsorption equilibrium time of metal ions in each system, we determined the specific sorption capacity (Nfmax) through adsorption isotherms. For Cu2+, the values of Nf were: aqueous solution (3.09 × 10-4 mol g-1), 42% ethanolic (1.03 × 10-4 mol g-1) and 99% ethanolic (1.86 × 10-4 mol g-1), with Cu2 + ion concentrations ranging from 1.74 to 29.64 mol L-1. The values obtained for the Ni2+ were: aqueous solution (2.11 × 10-4 mol g-1), 42% ethanolic (0.97 × 10-4 mol g-1) and 99% ethanolic (1.05 × 10-4 mol g-1), with Ni2 + ion concentrations ranging from 2.25 to 33.18 mol L-1. For the cadmium ions were not observed saturation of adsorption sites in the concentration range studied, not getting the maximum... (Summary complete electronic access click below)

Os modos de interação de silsesquioxano poliédrico oligomérico (POSS) de gaiolas fechadas com distintos grupos funcionais foram avaliados na nanoestruturação de polipropileno isotático (iPP) via processamento reativo. Analisaram-se POSS com grupos substituintes isobutila, alila e vinila em concentrações de 0,5, 1, 2 e 5%m misturados a iPP fundido utilizando peróxido de dicumila (DCP) como iniciador. Na caracterização dos nanocompósitos foram utilizadas diversas técnicas. A morfologia foi avaliada através de cromatografia por exclusão de tamanho, espectroscopia de infravermelho com transformada de Fourier, microscopia de transmissão e difração de raios X. O comportamento viscoelástico dos materiais no estado fundido foi medido por reologia oscilatória e no estado sólido por análises dinâmico-mecânicas. As transições térmicas foram levantadas tanto por análises dinâmico-mecânicas como por calorimetria diferencial de varredura. Modificações morfológicas e viscoelásticas importantes foram observadas para os nanocompósitos em dependência do tipo e teor de POSS empregado. A adição do Octaisobutil-POSS (OI) sugere ação estabilizante radicalar e lubrificante para este POSS. Os efeitos da incorporação do Alilisobutil-POSS (AL) indicam que este atuou como agente plastificante em função da concentração. Com Octavinil-POSS (OV) os nanocompósitos parecem adquirir estrutura ramificada ou interligada em dependência da concentração. A ativação radicalar promovida pelo DCP mostrou-se fundamental na enxertia de alguns POSS. Assim, a forma e intensidade das interações entre nanocargas e matriz foram definidas pelos grupos funcionais e concentração dos POSS. Alterações observadas na morfologia, propriedades térmicas e viscoelásticas são resultantes dessas formas e graus de interação. Deste modo, foi possível propor mecanismos de interação e arranjos morfológicos entre iPP, DCP e POSS pela avaliação do conjunto de resultados obtidos. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-10-06T16:44:04Z No. of bitstreams: 1 Dissertacao Sergio Graniero Echeverrigaray.pdf: 3289598 bytes, checksum: f804be75d287c3fd55eeb0690f47dfab (MD5) / Made available in DSpace on 2015-10-06T16:44:04Z (GMT). No. of bitstreams: 1 Dissertacao Sergio Graniero Echeverrigaray.pdf: 3289598 bytes, checksum: f804be75d287c3fd55eeb0690f47dfab (MD5) / The interaction modes of polyhedral oligomeric silsesquioxane (POSS) of closed cages with distinct functional groups were evaluated on isotactic polypropylene (iPP) nanostructuration via reactive processing. POSS were analyzed with isobutyl, allyl and vinyl substituent groups in concentrations of 0.5, 1, 2 and 5m% mixed with melting iPP using dicumil peroxide (DCP) as initializer. Several techniques were used to characterize the nanocomposites. The morphology was evaluated through size exclusion chromatography, Fourier transformed infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The samples viscoelastic behavior in melting state was measured by oscillatory rheometry and in solid state by dynamic mechanical analysis. The thermal transitions were obtained through dynamic mechanical analysis and differential scanning calorimetry. Important morphology and viscoelastic modifications were observed in nanocomposites by dependency on the type and content of POSS used. The addition of OctaIsobutyl-POSS (OI) suggests lubricant and radicalar stabilizing action for this POSS. The AllylIsobutyl-POSS (AL) incorporation effects indicate that this one acted as plasticizing agent in function of concentration. With OctaVinyl-POSS (OV), the nanocomposites seem to acquire ramified or interlinked structure in dependency on concentration. The radicalar activation promoted by DCP was decisive in the grafting efficiency for some POSS. Therefore, the mode and the interaction intensity between nanoparticles and polymeric matrix were defined by functional groups and POSS concentration. Changes observed in morphology, thermal and viscoelastic properties as in solid state as in melting state are results of these modes and interaction degrees. It was possible to propose interaction mechanisms and morphology arrangements among iPP, DCP and POSS by evaluation of the obtained results as a whole.

Os modos de interação de silsesquioxano poliédrico oligomérico (POSS) de gaiolas fechadas com distintos grupos funcionais foram avaliados na nanoestruturação de polipropileno isotático (iPP) via processamento reativo. Analisaram-se POSS com grupos substituintes isobutila, alila e vinila em concentrações de 0,5, 1, 2 e 5%m misturados a iPP fundido utilizando peróxido de dicumila (DCP) como iniciador. Na caracterização dos nanocompósitos foram utilizadas diversas técnicas. A morfologia foi avaliada através de cromatografia por exclusão de tamanho, espectroscopia de infravermelho com transformada de Fourier, microscopia de transmissão e difração de raios X. O comportamento viscoelástico dos materiais no estado fundido foi medido por reologia oscilatória e no estado sólido por análises dinâmico-mecânicas. As transições térmicas foram levantadas tanto por análises dinâmico-mecânicas como por calorimetria diferencial de varredura. Modificações morfológicas e viscoelásticas importantes foram observadas para os nanocompósitos em dependência do tipo e teor de POSS empregado. A adição do Octaisobutil-POSS (OI) sugere ação estabilizante radicalar e lubrificante para este POSS. Os efeitos da incorporação do Alilisobutil-POSS (AL) indicam que este atuou como agente plastificante em função da concentração. Com Octavinil-POSS (OV) os nanocompósitos parecem adquirir estrutura ramificada ou interligada em dependência da concentração. A ativação radicalar promovida pelo DCP mostrou-se fundamental na enxertia de alguns POSS. Assim, a forma e intensidade das interações entre nanocargas e matriz foram definidas pelos grupos funcionais e concentração dos POSS. Alterações observadas na morfologia, propriedades térmicas e viscoelásticas são resultantes dessas formas e graus de interação. Deste modo, foi possível propor mecanismos de interação e arranjos morfológicos entre iPP, DCP e POSS pela avaliação do conjunto de resultados obtidos. / The interaction modes of polyhedral oligomeric silsesquioxane (POSS) of closed cages with distinct functional groups were evaluated on isotactic polypropylene (iPP) nanostructuration via reactive processing. POSS were analyzed with isobutyl, allyl and vinyl substituent groups in concentrations of 0.5, 1, 2 and 5m% mixed with melting iPP using dicumil peroxide (DCP) as initializer. Several techniques were used to characterize the nanocomposites. The morphology was evaluated through size exclusion chromatography, Fourier transformed infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The samples viscoelastic behavior in melting state was measured by oscillatory rheometry and in solid state by dynamic mechanical analysis. The thermal transitions were obtained through dynamic mechanical analysis and differential scanning calorimetry. Important morphology and viscoelastic modifications were observed in nanocomposites by dependency on the type and content of POSS used. The addition of OctaIsobutyl-POSS (OI) suggests lubricant and radicalar stabilizing action for this POSS. The AllylIsobutyl-POSS (AL) incorporation effects indicate that this one acted as plasticizing agent in function of concentration. With OctaVinyl-POSS (OV), the nanocomposites seem to acquire ramified or interlinked structure in dependency on concentration. The radicalar activation promoted by DCP was decisive in the grafting efficiency for some POSS. Therefore, the mode and the interaction intensity between nanoparticles and polymeric matrix were defined by functional groups and POSS concentration. Changes observed in morphology, thermal and viscoelastic properties as in solid state as in melting state are results of these modes and interaction degrees. It was possible to propose interaction mechanisms and morphology arrangements among iPP, DCP and POSS by evaluation of the obtained results as a whole.