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König, Heinrich Josef. "Silsesquioxane mit oligomeren Käfigstrukturen". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967650496.
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Xu, Lan. "Synthesis of Perylenediimide-Functionalized Silsesquioxane Nanostructures". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1371.
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Organic semiconductors functionalized nanostructures are becoming as promising materials for electronic device applications including organic photovoltaics (OPVs). Perylenediimide (PDI) derivatives have also been known as one of the best n-type organic semiconductors. PDI derivatives can form bulk materials, which are both photochemically and thermally stable and have been widely used in various optoelectronic devices. Due to the formation of high electron mobility of crystalline domains, they prefer to incorporate into a silsesquioxane network. Here, we describe the potential applicability of perylenediimide functionalized silsesquioxane nanoribbons (PDI-dimethyl nanoribbons) as an acceptor for optoelectronic devices. We have developed synthetic procedures to make the PDI-dimethyl nanoribbons by the substitution reaction and the modified Stöber method. The PDI-dimethylethoxy silane precursor was produced in high yield by substituting 3-aminopropyldimethylethoxysilane on perylene-3,4,9,10-tetracarboxylicdianhydride as side chains. The optically active PDI-dimethyl nanoribbons were then formed upon hydrolysis with the certain concentration of ammonium hydroxide as a base. These nanoribbons were characterized using transmission electron microscopy (TEM), elemental analysis, and polarized optical microscopy. The photophysical properties in solution phase were also studied. The synthesis procedure developed here will have a great promise in large-scale manufacturing. Different shapes of PDI-dimethyl nanostructures, such as nanorods, nanochains, and nanoparticles, were discovered while varying the base concentrations. Also the morphologies of these PDI nanostructures were studied using TEM. Future studies will focus on optimizing procedures of PDI-dimethyl nanostructures and exploring new derivatives like perylenediimide dimer functionalized silsesquioxane polymers.
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Yang, Yuxing. "Synthesis and rearrangement of silsesquioxane cages". Thesis, Open University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393194.
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Soares, Isaac Vaz. "Síntese e caracterização de suportes a base de óxidos de silício modificados". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152609.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este trabalho descreve as sínteses e caracterizações de materiais à base de silício organofuncionalizados com 2-amino-5-(4-piridil)-1,3,4-tiadiazol (T8-Pr-APT e SG-Pr-APT) e 4 -amino-5-(4-piridil)-4H-1,2,4-triazol-3-tiol (T8-Pr-APTT e SG-Pr-APTT). Os materiais foram caracterizados por: espectroscopia na região do infravermelho (FTIR), ressonância magnética nuclear 29Si e 13C no estado sólido (RMN) e Microscopia eletrônica de varredura com Espectroscopia de energia dispersiva de raios-X (MEV-EDS). Nos estudos de batelada para os materiais, foram utilizados os íons metálicos de V(III), Fe(III), Cr(III), Cu(II), Pb(II) e os solventes foram água e etanol. Determinou-se a dose de adsorvente na solução e o tempo de equilíbrio, na qual, para o material T8-Pr-APT em todos os meios para os metais Cu, Pb e Cr, a capacidade máxima de adsorção ocorreu em 60 mg de adsorvente e para os metais restantes de 100 mg de adsorvente, o equilíbrio de adsorção em ambos os meios foi de aproximadamente 20 minutos para os metais Cu, Pb e Cr e 30 minutos para os demais, enquanto que, para o SGPr- APT em todos os meios para os metais Cu e Cr, a capacidade máxima de adsorção ocorreu em 60 mg de adsorvente e para os metais restantes de 100 mg de adsorvente, o equilíbrio de adsorção em ambos os meios foi de aproximadamente 40 minutos para todos os metais estudados. Estudou-se ainda a capacidade máxima de adsorção (Nf) para os solventes, na qual a capacidade máxima se deu em meio etanólico > aquoso. Em seguida, as isotermas de adsorção foram ajustadas pelos modelos Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Para cinética de adsorção dos metais, foram usados três modelos cinéticos como pseudoprimeira- ordem, pseudo-segunda-ordem e Elovich. Os modelos de Langmuir e Elovich foram os mais apropriados para descrever os dados de adsorção e cinética, respectivamente, de todos materiais. Os parâmetros termodinâmicos ΔGº, ΔHº e ΔSº foram avaliados para os materiais e observou-se que a adsorção de todos os metais, independentemente do adsorvente utilizado, foi um processo endotérmico e espontâneo, devido aos valores positivos de entalpia e negativo de energia livre de Gibbs, respectivamente. Os valores positivos da entropia indicam que o processo de adsorção é favorável e ocorre um aumento da desordem na interface sólido-solução. Estes resultados mostraram que os materiais possuem o mesmo comportamento termodinâmico. A atividade catalítica dos materiais suportados foram testados e comparados, utilizando complexo de molibdênio e tungstênio para epoxidação do 1-octeno, cicloocteno, cis-3-hexen- 1-ol, trans-3-hexen-1-ol e estireno, utilizando como oxidante o hidroperóxido de terc-butil (TBHP), onde ambos os materiais possuem semelhantes conversões e uma boa seletividade.
This work describes how syntheses and characterizations of silicon-based materials organofunctionalized with 2-amino-5- (4-pyridyl) -1,3,4-thiadiazole (T8-Pr-APT and SG-Pr- APT) and 4- Amino-5- (4-pyridyl) -4H-1,2,4-triazol-3-thiol (T8-Pr-APTT and SG-Pr-APTT). The materials were characterized by: infrared spectroscopy (FTIR), 29Si and 13C solid state nuclear magnetic resonance (NMR) and scanning electron microscopy with X-ray dispersive energy spectroscopy (SEM-EDS) V (III), Fe (III), Cr (III), Cu (II), Pb (II) and the solvents for ethanol and water. Determination of a adsorption dose in the solution and the equilibration time in quality for the T8-Pr-APT material in all media for the Cu, Pb and Cr metals, a maximum adsorption capacity occurred in 60 mg of adsorbent and for the remaining 100 mg adsorbent, the adsorption equilibrium in both media for approximately 20 minutes for the Cu, Pb and Cr metals and 30 minutes for the others, whereas for the SG-Pr-APT at all means for Cu and Cr metals, a maximum adsorption capacity occurred at 60 mg adsorbent and for other 100 mg adsorbent, the adsorption equilibrium in both media was about 40 minutes for all metals studied. A maximum adsorption capacity (Nf) was also studied for the solvents, in which a maximum capacity is given in ethanolic> aqueous medium. Then, as adsorption isotherms were adjusted by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) models. For kinetics of adsorption of metals, three kinetic models were used as pseudo-first-order, pseudo-second order and Elovich. The Langmuir and Elovich models were more adequate to describe the adsorption and kinetic data, respectively, of all materials. The thermodynamic parameters ΔGº, ΔHº and ΔSº were evaluated for the materials and it was observed that an adsorption of all metals, independently of the adsorbent used, for an endothermic and spontaneous process, for the enthalpy and negative positive values of Gibbs free energy , respectively. The positive entropy values indicate that the adsorption process is favorable and an increase in the disorder occurs at the solid-solution interface. These results show that the materials have the same thermodynamic behavior. The catalytic activity of the supported materials was tested and compared using a molybdenum and tungsten complex for the epoxidation of 1-octene, cyclooctene, cis-3-hexen-1-ol, trans-3-hexen-1-ol and styrene, Oxidant Or tert-butyl hydroperoxide (TBHP), where both materials have conversions and good selectivity
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Cai, Jun. "Photoluminescence studies of silsesquioxanes (SiO1.5)nRn and some selected organosilicon compounds". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965479447.
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Luvison, Caroline. "Preparação e caracterização de novos materiais híbridos a partir de (3-aminopropil) trimetoxisilano". reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1349.
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Nesse trabalho, foi investigada a obtenção de novos materiais a partir de reações de hidrólise e condensação ácida do (3-aminopropil)trimetoxisilano, que resultaram na formação de nanoestruturas híbridas com grupos amônios e contraíons cloreto (POSS-NH3Cl). As nanoestruturas posteriormente foram submetidas a trocas iônicas durante 0,5, 2, 12 e 48 h, para remoção dos íons cloreto. As análises titulométricas mostraram que a troca iônica ocorreu parcialmente. As partículas de POSS-NH2 formadas apresentam predominância de estruturas em forma de gaiola (T8) octafuncionalizadas. Após a troca iônica, as nanoestruturas possuem capacidade de se autoassociar por meio de interações eletrostáticas formando estruturas do tipo blackberry com aproximadamente 100 nm. Os aglomerados de POSS-NH2 são formados por partículas primárias com tamanho de 1,4 nm em forma de fractal de massa e tamanho de correlação () dependente da quantidade do tempo de troca iônica. Devido à característica eletrostática das partículas foi possível obter filmes híbridos opticamente transparentes com elevado grau de hidrofilicidade. As nanopartículas de POSS-NH2 foram utilizadas como aditivo de lubrificantes de fontes renováveis (ácidos graxos) por meio de reações de amidação direta assistida por micro-ondas, sem o uso de catalisadores. A formação das ligações amidas foi constatada por meio das técnicas FTIR e RMN de 1H, onde observaram-se bandas de deformação angular do NH em 1550 cm-1 e 1120 cm-1 e o aparecimento de um singleto alargado em 6,50 ppm (N-H). Em termos estruturais, para o biolubrificante foi constatado que uma molécula de ácido graxo liga com uma molécula de POSS-NH2, entretanto foi notada ainda a existência de aglomerados após a amidação, conforme resultados de MET dos lubrificantes. O uso de POSS-NH2 reduziu a taxa de oxidação dos biolubrificantes com dependência do tempo de troca iônica das partículas. Todos os biolubrificantes apresentaram comportamento reológico newtoniano, e a viscosidade a 25ºC mostrou-se dependente da quantidade de partículas e não do tempo de troca iônica. A adição de nanopartículas de POSS-NH2 melhorou o desempenho dos biolubrificantes aplicados em superfícies metálicas, visto que tribossistema estudado apresentou valores inferiores e mais estáveis de coeficiente de atrito em comparação com o óleo base. Além disso, os biolubrificantes apresentaram uma elevada capacidade do suporte de carga, que representa a carga crítica para a ocorrência de engripamento (scuffing) do sistema. A resistência ao desgaste das superfícies metálicas variou com a adição de partículas no óleo lubrificante e com os tempos de troca iônica adotados para a síntese das partículas.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-10-17T17:00:31Z No. of bitstreams: 1 Tese Caroline Luvison.pdf: 4503708 bytes, checksum: 86b0b05a5ba2a8c5180438f872bfe537 (MD5)
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Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS
In this work, was investigated the obtaining of new materials from the hydrolysis and acid condensation reactions of (3-aminopropyl) trimethoxysilane, which resulted in the formation of hybrid nanostructures with ammoniums groups and counter ions chloride (POSS-NH3Cl). The nanostructures were subjected to ion exchange procedures for 0.5, 2, 12 and 48 h for the removal of chloride ions. The titrimetric and volumetric results showed that the ion exchange occurred partially. The synthesized particles are predominantly POSS-NH2 cage-shaped structures (T8). After the ion exchange, the nanostructures have ability to selfassembly through electrostatic interactions forming the blackberry-like structures with approximately 100 nm. The POSS-NH2 cluster are formed by primary particles with a size of 1.4nm structured in form of a mass fractal with correlation length () dependent on the ion exchange time. Due to the electrostatic characteristic of the particles was possible obtained hybrid films optically transparent with a high degree of hydrophilicity. POSS-NH2 nanoparticles were used as additive of lubricants of renewable sources (fatty acids) by means of microwave-assisted direct reactions of amidation, without the use of catalysts. The formation of amide bonds were confirmed through the FTIR and 1H NMR techniques, where angular deformation bands in NH in 1550 cm-1 and 1120 cm-1 and the appearance of an enlarged singlet in 6.50 ppm (NH) were observed. The biolubricants was found that an alloy fatty acid molecule with a POSS, but has not yet noticed the existence of agglomerates after amidation, as TEM results of biolubricants. The POSS-NH2 are bonded individually to only one fatty acid molecule, however it was noted the existence of cluster after amidation reactions, as observed in TEM results of the biolubricants. The addition of POSS-NH2 nanoparticles reduced the oxidation rate of the biolubricants and has dependence on the ion exchange time. All the biolubricants showed a Newtonian rheological behavior and the viscosity at 25°C dependent on the amount of particles and not the exchange time. The addition of POSS-NH2, improved the performance of the biolubricants applied on metallic surfaces, since the studied sliding pair showed lower and more stable values of coefficient of friction, as compared to the base oil. Moreover, the biolubricants showed a high load support capacity, which represents the critical load for the scuffing occurrence of the system. The wear resistance of the metallic surfaces changed with the addition of POSS particles in the lubricant oil and with the ionic exchange time adopted for the synthesis of the particles.
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Liu, Zhihua. "Synthesis and reactions of novel silsesquioxane cages". Thesis, Open University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397913.
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Gentle, Theresa Eileen. "Octopus and dendrimer molecules with silsesquioxane cores". Thesis, Open University, 1995. http://oro.open.ac.uk/57544/.
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The interest in materials with designed physical properties and controlled molecular formula is increasing. Octopus molecules, or materials with pendent groups from a core, and dendrimer molecules, or materials with a defined pattern of branching from a core are means of obtaining molecules of designed architecture. The work presented here involves the synthesis and characterization of octopus and dendrimer molecules of defined shape with molecular weights well into the thousands. These designed molecular materials have been synthesized by placing pendant groups symmetrically about a silsesquioxane [(SiO3/2)8] core. A facile, one-step route to hydrocarbon and siloxane functional octopus molecules via H2PtC16 catalyzed hydrosilylation of 1-alkenes and vinyl-functional siloxanes by T8 hydrogen silsesquioxane, (HSiO3/2)8, has been demonstrated. The chemistry of addition was studied, and it was found that while the addition of the I-alkenes to T8 was, regioprecise with only a-addition being observed, both a- and ß-addition occurred with vinyl siloxanes. In addition, H/vinyl exchange on silicon was observed to occur with addition of vinyl-siloxane to T8. The effect of the hydrosilylation catalyst, homogeneous and heterogeneous, on the regioselectivity of addition and on the extent of exchange on silicon has been evaluated via GPC and 13C and 29Si NMR. Investigations into the feasibility of placing a number of other moieties on the silsesquioxane core to show the almost limitless types of functional octopus molecules that can be made and to expand into dendritic molecules were also accomplished. For example polyether functional and mixed polyether/siloxane functional octopus molecules were synthesized and found to have interesting surface activity. The synthesis of an acrylate functional octopus molecule was accomplished and the product used to produce an ultra-violet curable coating. Finally, routes other than hydrosilylation to produce octopus and dendrimer molecules with silsesquioxane cores, for instance, the reaction of ROH with SiH of (SiO3/2)8, were developed and used to increase the types of functional octopus possible and to produce dendrimer molecules with silsesquioxane cores. The synthesis, characterization, and possible applications of silsesquioxane-based octopus and dendrimer molecules will be discussed.
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Schumacher, Manuela. "Smart organic-inorganic nanohybrids of functionalized silsesquioxane nanoparticles". kostenfrei, 2008. http://opus.ub.uni-bayreuth.de/volltexte/2009/549/.
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Neerudu, Sreeramulu Niharika. "Colloidal Self-Assembly of Multi-fluorescent Silsesquioxane Microparticles". TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1607.
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Self-assembly of colloidal microparticles is one of the strategies for making characteristic patterns. These versatile self-assemblies provide a route to elevate the efficiency of an electronic device. Silsesquioxane particles with various functionalities were synthesized by a modified Stöber condensation method. This thesis describes the synthesis of benzylchloride silsesquioxanes, benzylchloride-amine silsesquioxanes and amine-functionalized silsesquioxane particles with multi-fluorescent tags. The size and morphology of the particles were controlled by varying the concentration of base and anhydrous ethanol (solvent). The size distribution of particles was controlled by adjusting the molar ratios of organotrialkoxy silane, base, and ethanol concentrations. Through selective post-functionalization with fused arenes of anthracene and rhodamine, multifluorescent particles were obtained. Morphologies and optical properties of particles were characterized by TEM, SEM, fluorescence optical microscopy, and absorption and fluorescence spectroscopies. The composition of silsesquioxanes was confirmed by FTIR, thermogravimetric analysis, and elemental analysis. A versatile technique was developed for the self-assembly of particles on different polymer substrates by changing the colloidal suspension concentration and the polymer substrate.
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Capaldi, Franco Mario 1977. "Atomistic simulations of octacyclopentyl polyhedral oligomeric silsesquioxane polyethylene nanocomposites". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32388.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005."June 2005."
Includes bibliographical references.
As the scientific community develops the ability to create composites which incorporate nanoscopic filler particles, the detailed atomic arrangement and atomic interactions become significant in determining the composite properties. Nanoscopic fillers such as carbon nanotubes, polyhedral oligomeric silsesquioxane (POSS), and layered silicates have already been successfully used to improve the thermal and mechanical properties of polymers. On this length scale, details describing particle organization, interaction between particles, and interactions between particle and matrix are needed to understand the behavior of the composite. In this thesis, we use atomistic simulations to investigate the detailed behavior of a blended octacyclopentyl polyhedral oligomeric silsesquioxane (CpPOSS) / polyethylene (PE) nanocomposite. The model potential employed to describe the atomic interactions in these systems is capable of reproducing the experimental vibrational and crystal structures for the POSS well. The mechanical properties of an infinite crystal were calculated. The), are anisotropic with a Reuss average isotropic elastic modulus of 11.78 GPa. Simulations of CpPOSS/PE composites revealed that the POSS had a stiffening effect on the polymer. Simulations revealed that both PE and POSS dynamics as measured by translational and rotational diffusivities decreased, the glass transition temperature increased, and both the density and modulus increased with increasing POSS content. Micromechanical models were fit to the composite modulus which allowed effective mechanical particle sizes to be determined.
(cont.) The POSS was found to aggregate into small necklace structures which have internal ordering similar to the crystal phase. The formation of crystallites was found to be energetically favorable in this system. A coarse grained potential which accounts for both the attraction and orientation between particles was developed to aid the further study of aggregation and crystallization in these composites. The interface between the POSS and the polymer is found to consist of polymer chains aligned tangentially to the POSS cage. This layer has increased mobility tangential to the surface of the particle and decreased mobility in the radial direction. Though it is very thin, consisting of only 1 or 2 monolayers of polymer, due to the small size of the POSS particle, the weight fraction of polymer in the interfacial region is as high as 43 % in the 25 weight percent CpPOSS/PE composite. These simulations reveal the formation of structure on both the angstrom length scale in the polymer near the interface and the mesoscopic length scale between the POSS particles.
by Franko M. Capaldi.
Ph.D.
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Cho, Hosouk. "Chemical incorporation of polyhedral oligomeric silsesquioxane into thermoset matrices". Diss., Mississippi State : Mississippi State University, 2006. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
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Riaz, Ali 1981. "Functionalized polyhedral oligomeric silsesquioxane (POSS) for incorporation of chemically pendant chains = Utilização de silsesquioxanos oligoméricos poliédricos funcionalizados (POSS) no ancoramento de cadeias orgânicas à superfície". [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250644.
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Orientador: José de Alencar SimoniTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Este trabalho apresenta a síntese e caracterização de compostos silsesquioxanos gaiola cúbica (POSS) com cadeias orgânicas pendentes. O projeto foi iniciado com a idéia de sintetizar os silsesquioxanos cúbicos com cadeias organofuncionalizadas ancoradas, capazes de capturar os metais pesados, corantes e CO2. Mas foram enfrentadas algumas dificuldades como baixo rendimento (30-37%) e longo tempo de reação (5-35 dias). As reações foram investigadas para melhorar o rendimento, bem como para reduzir o tempo de reação. Algumas modificações em rotas de reação foram introduzidas, o que trouxe melhorias notáveis nos resultados, onde o rendimento aumentou cerca de 64 % e o tempo de reação foi reduzido para 24 horas em média. Na sequência, os produtos sintetizados foram caracterizados para elucidar suas estruturas, utilizando diferentes técnicas físicas tais como FTIR, CHN, XRD, MEV, TGA, 13CNMR e 29SiNMR no estado sólido, onde as gaiolas Si-O de todos os compostos foram evidenciadas por meio de 29SiRMN e dos seus espectros de FTIR, enquanto as cadeias ancorados às gaiolas de POSS foram confirmadas utilizando os resultados de 13CRMN, juntamente com seus respectivos espectros de FTIR. Os compostos sintetizados também foram testados quanto à sua estabilidade térmica utilizando a técnica de TGA. Após a otimização da síntese de silsesquioxanos cúbicos, os híbridos PAA-13-3, PAA-MTC e PAA-Ph foram avaliados por suas habilidades de captação de cátions bivalentes, tais como Cu2+, Cd2+ e Pb2+ de suas soluções aquosas, sendo que o Cu2+ apresentou maior afinidade de sorção em relação aos dois metais. Estes sistemas de sorção foram analisados através ICP-OES. Para explicar o comportamento de sorção destas amostras alguns modelos estatísticos como Langmuir, Freundlich, Temkin e Redlich-Peterson foram aplicadas, onde os dados de sorção de Cu2+ em PAA-13-3 foram melhor ajustados pelo modelo Langmuir, mostrando ser uma sorção monocamada, enquanto que no caso do PAA-MTC e PAA-Ph modelo de melhor ajuste foi o Freundlich, confirmando a sorção de múlti camadas. Um dos materiais sintetizados (PAA-13-3) foi avaliado quanto à sua capacidade de adsorver CO2 gasoso, mostrando-se promissor na remoção de CO2, mesmo a baixas pressões (máx. 100 mm Hg). A adsorção de CO2 no material também foi estudada por calorimetria de adsorção gás-sólido, em um calorímetro especialmente desenvolvido para tal, observando-se valores de entalpia de adsorção entre -36 e -7 kJ mol-1
Abstract: This report presents the synthesis and characterization of POSS compounds having cubic silsesquioxane cage to which the organic pendant chains are anchored. The project was started with the idea to synthesize the cubic silsesquioxanes with organofunctionalized pendant chains, which are able to capture heavy metals, dyes and some acids like CO2. But in the beginning the hurdles like low % yields (30-37 %) and long reaction times (5-35 days) were to be faced. The reactions were worked out to enhance the % yields as well as to reduce the reaction time. Some modifications in reaction routes have been introduced, which brought up remarkable improvements in the results, where yield was increased upto 64 % and reaction time was reduced to 1 day. All the synthesized products were then characterized for their structure elucidations using different physical techniques like FTIR, CHN, TGA, 13CNMR & 29SiNMR in solid state, where Si¿O cages of all compounds were elaborated through 29Si-NMR in solid state as well as through their respective FTIR patterns, while the pendant chains anchored to the POSS cages were confirmed using 13C-NMR results along with their respective FTIR spectra. The synthesized compounds were then tested for their thermal stability using the TGA technique. After optimizing the synthesis of cubic silsesquioxanes, hybrids PAA-13-3, PAA-MTC and PAA-Ph were worked out for their abilities of capturing divalent cations like Cu2+, Cd2+ and Pb2+ from their aqueous solutions, where Cu2+ showed higher affinity of sorption than other two bivalent metals. These sorption systems were analyzed using the ICP-OES. To explain the sorption behaviour of these samples some statistical models like Langmuir, Freundlich, Sips, Temkin and Redlich-Peterson were applied to the sorption data, where the data for Cu2+ on to PAA-13-3 was best fitted by Langmuir adsorption isotherm model showing the sorption to be monolayer, while in case of PAA-MTC and PAA-Ph Freundlich model was found to be a best fit, confirming multilayer sorption. One of the synthesized materials (PAA-13-3) was also evaluated for its ability to adsorb gaseous CO2 and was proved to be promising in removing CO2, even at low pressures (max. 100 mmHg). The adsorption of CO2 in the material is also studied by solid-gas adsorption calorimetry through a calorimeter especially developed for this system, where enthalpy of adsorption values were found to be between -7 and -36 kJ mol-1
Doutorado
Quimica Inorganica
Doutor em Ciências
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Reißig, Thomas. "Elektrochemie von redoxaktiv modifizierten Silsesquioxanen". [S.l. : s.n.], 2008.
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Freitas, Bianca Trama. "Leveduras quimicamente modificadas com silsesquioxanos cúbicos : avaliação como biossorvente e sensor eletroquímico /". Ilha Solteira, 2019. http://hdl.handle.net/11449/181340.
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Orientador: Devaney Ribeiro do CarmoResumo: A detecção, especiação e remoção de contaminantes orgânicos e inorgânicos é uma das maiores preocupações ambientais atualmente. Assim, a busca por tecnologias eficientes envolvendo materiais de baixo custo para a resolução de tal problema tem aumentado, e se tornou de extrema importância. Dentro deste contexto, o presente trabalho atuou na produção de um novo material nanoestruturado bioinorgânico híbrido com grandes potencialidades na área de nanotecnologia. O objetivo principal consistiu em modificar quimicamente a levedura Saccharomyces cerevisiae com silsesquioxanos cúbicos. Após devidas modificações, o material preparado (LevS) bem como seus precursores, foram caracterizados por técnicas espectroscópicas tais como infravermelho (FTIR) e microscopia eletrônica de varredura (MEV). O material hibrido formado (LevS) foi aplicado como biossorvente de chumbo (Pb) e níquel (Ni), obtendo-se uma capacidade máxima de sorção de 248 mg g-1 e 64,6 mg g-1, respectivamente, e porcentagem de sorção chegando a 100% para 500 ppm de Pb2+ em 250mLg-1 de razão líquido/sólido em pH 4, e 77,7% para 100 ppm de Ni2+ em 100 mLg-1 de razão líquido/sólido em pH 6. Adicionalmente com intuito de avaliar a toxidade neuronal dos metais em questão, foram efetuados testes de toxicidade em fatias de hipocampo de ratos que comprovaram que, uma vez submetidos à concentrações de 1 e 3 μM (0,2 e 0,6 ppm) Pb2+ e 10 e 30 μM (0,5 e 1,5 ppm) de Ni2+, as alterações neuronais causadas são irreversíveis. O material ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The detection, speciation and organic and inorganic contaminants removal is one of the biggest environmental concerns today. Thus, the search for efficient technologies involving low-cost materials for solving such a problem has increased, and became extremely important. Within this context, the present work was focused in the production of a new nanostructured hybrid material bioinorganic with great potential in the area of nanotechnology. The main objective was chemically modify the yeast Saccharomyces cerevisiae with cubic silsesquioxane. After appropriate modifications, the prepared material (LevS) as well as its precursors was characterized by spectroscopic techniques such as infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDS) and Diffuse Reflectance UV/Vis. The hybrid material formed (LevS) was applied as biosorbent of lead (Pb) and nickel (Ni), with a maximum capacity of sorption of 248 mg g-1 and 64.6 mg g-1, respectively, and percentage of reaching 100% sorption to 500 ppm of Pb2+ on 250 cm3 g-1 liquid/solid ratio and 4 pH, and 77.7% to 100 ppm of Ni2+ on 100 cm3 g-1 liquid/solid ratio at pH 6. In addition, in order to evaluate the neuronal toxicity of the metals in question, toxicity tests were performed on hippocampal slices of mice that proved that, once submitted to concentrations of 1 and 3 μM (0.2 and 0.6 ppm) Pb2+ and 10 and 30 μM (0.5 and 1.5 ppm) of Ni2+, neuronal changes caused are irreversible. The hybrid material was also te... (Complete abstract click electronic access below)
Doutor
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Kannan, R. Y. "Development of silsesquioxane-polyurethane nanocomposites for use in microvascular networks". Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445620/.
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We have recently developed a nanocomposite based on polyhedral oligomeric silsesquixoane for medical device application for particular use in a microvascular network. Using spectroscopic analyses, we characterised the polymer before subjecting it to both in vitro and in vivo degradation. In the same setting, the foreign- body reaction of this polymer was determined. An in vitro feasibility study as to the efficacy of neo-endothelialisation was then performed. Next, the anti-thrombogenic nature of the nanocomposite was elicited. Based on the favourable outcomes of these experiments, nanocomposite microvessels were designed and fabricated to form the components of a microvascular network. Our results indicate that silsesquioxane is an optimal building material for microvascular grafts. This therefore constitutes the foundation on which we intend to construct an in vitro artificial capillary bed model.
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Clarke, David John, i d. clarke@irl cri nz. "The Synthesis and Characterisation of Polyhedral Oligomeric Silsesquioxane Bound Chromophores". Flinders University. School of Chemistry, Physics and Earth Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20080908.074728.
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This research involved the synthesis and characterisation of a range of optically active polyhedral oligomeric silsesquioxane (POSS) compounds.
POSS precursor compounds containing functional groups required for subsequent attachment of the desired functional groups have been synthesised. Examples of such precursor compounds include mono-functionalised POSS compounds with periphery aldehyde, azide, amino and pyridyl functional groups.
A variety of POSS compounds, functionalised with a range of optical functionalities, including optical limiters such as fulleropyrrolidine and iminofullerene, and dyes and pigments, including naphthalene, biphenyl, perylene, pyrene and porphyrin have been synthesised.
The reaction of mono-functionalised POSS aldehydes with fullerene (C60) in the presence of N-methylglycine yielded the desired POSS fulleropyrrolidines, whilst reaction of mono-functionalised POSS azide with C60 yielded POSS iminofullerenes. All POSS fullerene compounds were characterised by power limiting measurements, exhibiting comparable power limiting to that of parent C60.
The microwave condensation of mono-amino POSS with a range of mono- and bis-anhydrides yielded the POSS imide compounds, which were characterised by UV-Vis and fluorescence spectrophotometry. The perylene POSS imide derivative was further characterised by single crystal x-ray crystallography. The naphtha and biphenyl POSS imides exhibited extremely weak fluorescence, whilst the perylene
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POSS imide displayed particularly strong fluorescence, with a quantum yield approaching unity.
The incorporation of a pyridyl group on the periphery of a mono-functionalised POSS cage allowed for the synthesis of the first porphyrin functionalised POSS compound. Mono-porphyrin POSS exhibited comparable absorption properties to other pyridyl ligated ruthenium porphyrins.
Mono-functionalised pyrene POSS compounds were prepared through the reaction of 1-pyrene acid chloride with mono(3-aminopropyl)POSS. This synthetic pathway offered a convenient route to mono-functionalised pyrene POSS, in preference to the multi-substitution associated with Heck coupling. Mono-pyrene POSS was determined to be strongly fluorescent, exhibiting a high quantum yield of fluorescence
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Pourny, Manuel. "The preparation of encapsulated flouride anion in T8 silsesquioxane cages". Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418463.
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Liu, Yang. "Synthesis and Characterization of Polyhedral Oligomeric Silsesquioxane (POSS) Based Amphiphiles". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77182.
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Polyhedral oligomeric silsesquioxanes (POSS) have attracted substantial academic interest for many years as hybrid materials and nanofillers for controlling thermal and mechanical properties, and providing thermal and chemical resistance while retaining ease of processing. A natural extension of these studies has been POSS-based amphiphiles and thin film coatings. Studies at the air/water (A/W) interface have shown that trisilanol-POSS derivatives are amphiphilic and form uniform Langmuir films, whereas closed-cage POSS derivatives are hydrophobic and aggregate.
In previous work, a triester (POSS-triester) and a triacid (POSS-triacid) were synthesized from PSS-(3-hydroxypropyl)-heptaisobutyl (POSS-OH) and Weisocyanate and fully characterized by surface pressure – area per molecule (Π-A) isotherm and Brewster angle microscopy (BAM) studies at the A/W interface. The results indicated that POSS-triester is surface active forming a liquid expanded (LE) monolayer, whereas POSS-triacid forms a liquid condensed (LC) monolayer that is only weakly affected by pH. A face-on conformation was proposed and examined to understand the packing of POSS-based amphiphilic molecules at the A/W interface. The face-on/vertex-on comparison is rarely discussed for Langmuir monolayers at the A/W interface.
In this thesis, three other POSS-based esters were synthesized from POSS-OH and aminopropylisobutyl-POSS (POSS-NH₂) using Weisocyanate and a similar isocyanate containing two tert-butyl protected carboxylic acids. The synthesized materials are characterized by Π-A isotherm and BAM. For POSS-OH based diester (PAlDE) and POSS-NH2 based diester (PAmDE), LE/LC phase transitions were observed in Π-A isotherms over part of the experimentally accessible temperature range and were attributed to a change from a vertex-on to face-on conformation. Apparent BAM images confirmed LC islands coexisted with the LE phase. The experimentally observed dynamic estimates of the critical temperatures (Tc) were estimated from a two-dimensional Clausius-Clapeyron analysis and were consistent with the temperature dependence of the Π-A isotherms. These LE/LC phase transitions are the first observed for POSS amphiphiles.Ph. D.
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Liu, Yang. "Synthesis and Characterization of Polyhedral Oligomeric Silsesquioxane (POSS) Based Amphiphiles". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/76922.
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Polyhedral oligomeric silsesquioxanes (POSS) have attracted substantial academic interest for many years as hybrid materials and nanofillers for controlling thermal and mechanical properties, and for providing thermal and chemical resistance while retaining ease of processing. A natural extension of these studies has been working on POSS-based amphiphiles and thin film coatings. Studies at the air/water (A/W) interface have shown that trisilanol-POSS derivatives are amphiphilic and form uniform Langmuir films, whereas closed-cage POSS derivatives are hydrophobic and aggregate.
In this study, two novel POSS derivatives were synthesized from PSS-(3-hydroxypropyl)-heptaisobutyl substituted (POSS-OH) and completely characterized. Weisocyanate reacted with POSS-OH, and a POSS-based triester (POSS-triester) was obtained. Trifluoroacidolysis of the POSS-triester at room temperature afforded the corresponding triacid (POSS-triacid). Purified POSS-OH, POSS-triester, and POSS-triacid were studied by using surface pressure - area per molecule (? -A) isotherms as well as Brewster angle microscopy (BAM) at the air/water (A/W) interface. Compared with previous work on trisilanol-POSS derivatives, the results indicated that POSS-triester was surface active and formed a liquid-expanded (LE) monolayer. In contrast, POSS-triacid monolayers were more condensed (LC) and were not dramatically affected by changes in pH. Results for the lift-off areas (Alift-off), limiting areas (A0), collapse areas (Ac), and collapse pressures (? c) of POSS-OH, POSS-triester, and POSS-triacid were compared to trisilanolisobutyl-POSS (TiBP) and were interpreted in terms of possible molecular conformations. Whereas, TiBP has been hypothesized to exist in a vertex-on conformation, POSS-OH and POSS-triacid packing at the A/W interface was consistent with face-on conformations. For POSS-triester, the isotherm was consistent with a vertex-on conformation at low ? , but a face-on conformation at high ? .Master of Science
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Hörner, Sebastian [Verfasser], Harald [Akademischer Betreuer] Kolmar i Siegfried [Akademischer Betreuer] Neumann. "Biofunctionalization of Silsesquioxane Nanoparticles / Sebastian Hörner ; Harald Kolmar, Siegfried Neumann". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1136422846/34.
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Kulkarni, Pallavi P. "Effect of polyhedral oligomeric silsesquioxane on gas transport properties of polyimide /". Connect to full text in OhioLINK ETD Center, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1196883179.
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Dissertation (Ph.D.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy degree in the Engineering Science Concentration in Chemical and Environmental Engineering." Bibliography: leaves 213-221.
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Peak, Sarah M. "SELECTIVE TRIPODAL TITANIUM SILSESQUIOXANE CATALYSTS FOR THE EPOXIDATION OF UNACTIVATED OLEFINS". UKnowledge, 2015. http://uknowledge.uky.edu/chemistry_etds/52.
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Regiomeric mixture of HMe2Si(CH2)3(i-Bu)6Si7O9(OH)3 (6), containing a Si-H group in one of the ligands of the silsesquioxane, was tethered onto a vinyl terminated hyperbranched poly(siloxysilane) polymer via a hydrosilation reaction to generate extremely active catalysts, P1-8 and c-P1-8. The synthesis of 6, in good yield, was accomplished via hydrosilation of CH2=CHCH2(i-Bu)7Si8O12 (1) to generate ClMe2Si(CH2)3(i-Bu)7Si8O12 (3) followed by the reduction of 3 with LiAlH4 to afford HMe2Si(CH2)3(i-Bu)7Si8O12 (4) where the base-catalyzed excision of one framework silicon was employed to generate a regiomeric mixture of 6.
[Ti(NMe2){Et3Si(CH2)3(i-Bu)6Si7O12}] (7), [Ti(NMe2){HMe2Si(CH2)3(i-Bu)6Si7O12}] (8), [Ti(NMe2){(i-C4H9)7Si7O12}] (9) and [Ti(NMe2){(c-C6H11)7Si7O12}] (10) were synthesized via protonolysis of Ti(NMe2)4 with one equivalent of the trisilanol precursor in order to determine if the presence of isomers would be intrinsically different as compared to the uniformly substituted catalysts. Isomers 8 and 9, demonstrated lower activity as compared to the uniformly substituted catalysts 9 and 10, however the isomers still exhibited extremely high catalytic activity for the epoxidation of 1-octene using tert-butyl hydroperoxide (TBHP) relative to titanium catalysts used in industry. Additionally, 9, 10, P1-8 and c-P1-8 were very selective catalysts for the epoxidation of various olefins such as terminal (1-octene), cyclic (cyclohexene or 1-methylcyclohexene), and more demanding olefins (limonene or α-pinene) employing TBHP as the oxidant. Furthermore, P1-8 and c-P1-8 were recyclable with minimal loss of titanium however the catalysts could also be repaired if a loss in activity was observed.
Preliminary epoxidation reactions employing P1-8 and c-P1-8 along with hydrogen peroxide (H2O2) as the oxidant were also explored using different solvents. P1-8 degraded quickly due to the hydrolysis of the titanium from the large amount of water present in the reaction mixture however c-P1-8 showed activity for the epoxidation of cyclohexene. Finally, regiomeric mixture of Ti(NMe2)(HS(CH2)3)(i-C4H9)6Si7O12) (13), was tethered onto gold nanoparticles for the conversion of propene to propylene oxide using molecular hydrogen and oxygen. While the catalysts showed low activity under our reaction conditions, numerous improvements can be investigated in order to improve upon the catalysts.
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Bakhshi, R. "Coating stent materials with polyhedral oligomeric silsesquioxane-poly(carbonateurea)urethane nanocomposites". Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18987/.
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The long-term efficacy of coronary or peripheral stenting is limited by in-stent restenosis (ISR), which occurs in 15 to 30% of patients and is attributed primarily to neointimal hyperplasia. By adding a drug-eluting coating, this rate has been reduced to about 5% or less. However, recently longer-term follow-up data has highlighted problems with drug-coated stents, including late stage thrombosis. A bio-stable poly(carbonate-urea)urethane has been used for stent coating and the surface properties of the polymer have been optimised by incorporating the polyhedral oligomeric silsesquioxane molecule. These POSS polymers improve the adhesion and the growth of endothelial cells. The work described in this thesis, presents an innovative approach in self-expanding/balloon expandable coronary stent design that incorporates a NiTi/stainless steel alloy scaffold with a polyhedral oligomeric silsesquioxane- poly (carbonate-urea) urethane nanocomposite polymer (POSS-PCU) coating. Electrohydrodynamic spraying and ultrasonic atomization spraying of the non-biodegradable nanocomposite polyhedral oligomeric silsesquioxane (POSS) polymer have been investigated in detail for coating metallic stent materials and compared with dip coating. Because of the tight geometry of coronary stents, these new coating techniques have been shown to offer advantages over traditional coating techniques. These advantages include, reduced polymer consumption, precise coating thickness as low as 10 μm and a highly controllable spray which leads to consistent reproducible results. However, poor adhesion, or bond deterioration over the lifespan/ deployment of the device could reduces the efficiency and could impart even more complexity to the implant including formation of debris which can induce thrombus formation. Changing the surface physical property/chemical composition through the proposed protocol has been shown to increase the bonding strength by up to three times. This study has identified a new process and conditions which can be used in stent coating research.
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Kulkarni, Pallavi. "Effect of Polyhedral Oligomeric Silsesquioxane on Gas Transport Properties of Polyimide". University of Toledo / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1196883179.
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Magossi, Mariana de Souza. "Nanocompósitos híbridos a base de silsesquioxano e nitroprussiato de cobalto e zinco : preparação, caracterização e aplicações eletroanalíticas /". Ilha Solteira, 2019. http://hdl.handle.net/11449/181980.
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Orientador: Devaney Ribeiro do CarmoResumo: Neste trabalho, novos nanocompósitos híbridos a base de silsesquioxano e nitroprussiato de cobalto e zinco foram preparados, seguindo dois métodos de síntese. Os materiais preparados foram caracterizados empregando diferentes técnicas: Espectroscopia na Região do Infravermelho por transformada de Fourier (FTIR), Espectroscopia Raman, Espectroscopia de Reflectância Difusa UV/Vis, Ressonância Magnética Nuclear (RMN), Difração de Raios-X (DRX), Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva de Raios-X (EDX), Microscopia Eletrônica de Transmissão (MET) e Análise Termogravimétrica (TGA). Após a obtenção dos nanocompósitos com complexos metálicos de nitroprussiato (ACCoN e ACZnN), realizou-se um estudo sistemático sobre o comportamento voltamétrico desses materiais, empregando técnicas eletroquímicas, tais como: Voltametria Cíclica (VC) e Voltametria de Pulso Diferencial (VPD), utilizando eletrodos de pasta de grafite. O eletrodo de pasta de grafite contendo ACCoN mostrou-se sensível a concentrações de hidrazina e isoniazida. Já o eletrodo de pasta de grafite contendo ACZnN foi aplicado na detecção de N-acetilcisteína e isoniazida com sucesso. Após os testes de eletro-oxidação catalítica dessas substâncias, realizou-se uma investigação da influência dos principais interferentes, de forma que a interferência observada não se mostrou significativa. Avaliou-se também a recuperação destas substâncias a partir de amostras de água da torneira e urina sint... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work, new nanocomposites based on silsesquioxane and cobalt and zinc nitroprusside were prepared, following two synthetic methods. The prepared materials were characterized by different techniques: Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, UV-Vis Diffuse Reflectance Spectroscopy, Nuclear Magnetic Resonance (NMR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA). After obtaining the nanocomposites with metallic nitroprusside complexes, it was carried out a systematic study on the voltammetric behavior of these materials, using electrochemical techniques, such as: Cyclic Voltametry (CV) and Differential Pulse Voltammetry (DPV), using graphite paste electrodes. The graphite paste electrode containing ACCoN was sensitive to concentrations of hydrazine and isoniazid. The graphite paste electrode containing ACZnN was applied to the detection of N-acetylcysteine and isoniazid, with success. After catalytic electrooxidation tests of these substances, it was investigated the influence of the main interferents, so that the noticed interferences were not significant. Also, it was evaluated the recovery of these substances from samples of tap water and synthetic urine. By this way, the binuclear hybrid nanocomposites formed (ACCoN and ACZnN) are potential candidates for the construction of electrochemical sensors in the hydrazi... (Complete abstract click electronic access below)
Doutor
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Liang, Kaiwen. "Cyanate ester, epoxy and epoxy/cyanate ester matrix polyhedral oligomeric silsesquioxane nanocomposites". Diss., Mississippi State : Mississippi State University, 2005. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
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Taleb, Wassim. "Nanotechnology for corrosion control : silsesquioxane based nanofillers for iron carbonate film enhancement". Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17863/.
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Carbon dioxide internal corrosion is one of the most common degradation mechanisms occurring in oil and gas exploration and production environments when carbon steel is the material of construction. Both general and localized attack can lead to severe production cuts and safety incidents and these are commonly mitigated via the use of corrosion inhibitors, the deployment of which significantly increases the operational expenditure. When environmental conditions are favourable, a naturally growing corrosion product known as iron carbonate precipitates onto the internal pipe wall providing protection from degradation but only when it is well adherent to the surface and compact. To date, research trying to take advantage of the protective abilities of these naturally growing films is limited. The aim of this research is to encourage the iron carbonate kinetics of formation but also its mechanical properties via the addition of a hybrid organic-inorganic molecule to mimic the formation of a nanocomposite. This should allow for the modified iron carbonate to better resist mechanical removal in order to sustain its naturally inherent steel protection properties over a wider range of environmental conditions. Electrochemical results show how the addition of a silsesquioxane-based nanofiller acts as nucleating agent and accelerates the build-up of the iron carbonate corrosion products. Mechanical properties such as hardness and modulus extracted from nanoindentation tests ascertain that the modified corrosion products are more robust. This thesis describes a novel approach relying on the protectiveness of the corrosion layer growing in situ in oil and gas transport systems to mitigate carbon steel dissolution in specific environmental conditions. It is anticipated that the benefits of such a batch treatment of the nanofiller would be greater than for conventional film-forming inhibitors.
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Wu, Kan. "Syntheses and Characterization of Polyhedral Oligomeric Silsesquioxane Based Giant Molecular Shape Amphiphiles". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399564457.
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Omambala, Joshua R. "The Electrorheological Effect of Polyhedral Silsesquioxane Cage Structures with Cyanopropyl Functional Groups". Thesis, University of Louisiana at Lafayette, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10248880.
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Previous research has shown that POSS particles in silicone oil show significant ER activity. It is shown for the first time the effect of the number of the same functional groups attached to POSS cage structures on the electrorheological activity of these structures. Two compounds of the Octahedral geometry (T8) of cyanopropyl POSS was used for this investigation. One of the compounds was purchased (monofunctionalized cyanopropyl POSS) and the other was synthesized (octafunctionalized cyanopropyl POSS). The hydrolysation method has been used in the synthesis, the yield of the synthesized octafunctionalized POSS compound calculated and the both micrometer sized compounds characterized. The effects of the functional group attached to the inorganic silicon-oxygen core structure of the POSS compounds on the rheological properties is demonstrated through steady flow and oscillatory tests. Particular attention is paid to how the number of the cyano functional groups affects the behavior of these suspensions of cyanopropyl POSS compounds in silicone oil under increasing electric field strength. The research also contributed answers to the effects of changing the concentration of the cyanopropyl POSS particles in the suspension. The flow curve was described by the Herschel-Bulkley model and the Yield stress values ascertained from the model. The dielectric characterization was also done to support the ER response results which showed that the octafunctionalized compound gave a better response. The differences of the electrorheological properties of these compounds has also been discussed with the tests.
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Voisin, Doria. "Structuration d’organosilices : assemblage covalent et auto-organisation de T8- silsesquioxanes octa-fonctionnalisés". Thesis, Montpellier, Ecole nationale supérieure de chimie, 2016. http://www.theses.fr/2016ENCM0017/document.
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Le présent travail vise la synthèse d’organosilices nano-structurées à partir de briques élémentaires de silsesquioxanes polyédriques fonctionnalisées (T8-POSS) de structure cube (RSiO1,5)8. L’assemblage de briques fonctionnelles T8-POSS a été étudié selon deux voies : par des interactions fortes en formant des liaisons covalentes et par des interactions faibles en formant des liaisons hydrogène.La première partie décrit la formation de réseaux hybrides covalents à partir de structure T8 POSS portant huit fonctions aldéhydes. La synthèse et la structure cristalline de ces « cubes » fonctionnalisés sont décrites et la réactivité des fonctions aldéhydes est examinée. La formation de liaisons C=N par réaction d’amines conduit à des réseaux tridimensionnels grâce à la formation de ponts organiques bis-imines joignant les unités silsesquioxanes. Bien que la formation d’imine soit réversible, les solides obtenus ne présentent pas d’ordre à longue distance. La formation de liaisons C=C, dans des conditions de synthèse non réversibles, par réaction de bis-ylures de phosphonium avec les aldéhydes a également été étudiée. Ces réactions de type Wittig engendrent la formation de réseaux hybrides amorphes contenant des sous-structures phenylène-vinylènes dotées de propriétés de fluorescence. La deuxième partie décrit la synthèse de nouvelles molécules de T8-POSS, possédant des fonctions organiques amines ou acides carboxyliques capables d’interactions intermoléculaires grâce à des liaisons hydrogène. Ces interactions permettent l’assemblage des dérivés du T8-POSS fonctionnalisés par huit fonctions acides carboxyliques en un réseau 3D ordonné. Les briques élémentaires T8- POSS s’auto-assemblent par dimérisation des fonctions acides pour engendrer des silices hybrides cristallines. Les structures ont été déterminées par diffraction de rayons X. Les fonctions acides carboxyliques sont intéressantes non seulement par leur capacité à former des liaisons hydrogènes mais également par leur aptitude à former des carboxylates métalliques. Ces derniers ouvrent des perspectives pour la formation de réseaux d’oragnosilices incorporant des métauxThe present work aimed at synthesising nano-structured organosilicas using polyhedral silsesquioxane building blocks (T8-POSS) having a cube structure. The assembly of T8-POSS building blocks to form a 3D network was studied in two ways: first by formation of strong covalent bonds and secondly by formation of weak hydrogen bonds.The first part described the formation of covalent hybrid networks from T8-POSS structures with eight aldehyde functional groups. The synthesis and crystal structure of these functionalised silsesquioxane cubes is described and the reactivity of the aldehyde groups is studied. The formation of C=N bonds upon reaction with amines lead to tree-dimensional networks upon formation of bis-imine bridges linking the silsesquioxane units. Despite the imine formation was reversible, the resulting solids were amorphous materials and exhibited no long distance order. The formation of C=C bonds, under non-reversible reaction conditions, was achieved by reaction of phosphonium bis-ylides. The Wittig type reactions generated amorphous hybrid networks containing bridging phenylene-vinylene substructures with fluorescence properties.The second part described the synthesis of new functionalised T8-POSS cubes with eight amine or carboxylic acid functions capable of intermolecular interactions by hydrogen bonding. It allowed the assembly of the octa-carboxylique acid cubes to form an ordered 3D hybrid network. The T8-POSS building blocks self-assembled upon dimerization of the acid groups and generated crystalline hybrid silicas. The crystal structures were determined by X-ray diffraction. The use carboxylic acid groups is interesting because of its ability to form hydrogen bonds and also because of its ability to form metal carboxylate derivatives. It could lead to hybrid metal organic silica frameworks
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Soares, Layciane Aparecida [UNESP]. "Propriedades analíticas e eletroanalíticas de um silsesquioxano nanoestruturado organofuncionalizado". Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/91961.
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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)
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Liu, Chang. "GIANT LIPIDS BASED ON POLYHEDRALOLIGOMERIC SILSESQUIOXANE AND POLYSTYRENE:THE SELF-ASSEMBLY IN THE MELT". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1502879178237178.
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Bo, Ni. "Design, Synthesis and Self-assembly of Polyhedral Oligomeric Silsesquioxane (POSS) Based Hybrid Materials". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152130982499385.
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Narikiyo, Hayato. "Development of Functional Materials Based on Polyhedral Oligomeric Silsesquioxane with Flexible Side-Chains". Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263688.
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付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム京都大学
新制・課程博士
博士(工学)
甲第23227号
工博第4871号
京都大学大学院工学研究科高分子化学専攻
(主査)教授 田中 一生, 教授 秋吉 一成, 教授 古賀 毅
学位規則第4条第1項該当
Doctor of Philosophy (Engineering)
Kyoto University
DGAM
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Kathan, Kyle R. "An investigation of the nodular microstructure of selected silsesquioxane and epoxy thermosetting resins". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012142.
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Echeverrigaray, Sérgio Graniero. "Processamento reativo de nanocompósitos iPP-POSS". reponame:Repositório Institucional da UCS, 2009. https://repositorio.ucs.br/handle/11338/1028.
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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)
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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.
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Reverdy, Charlène. "Industrial applications of functional nanocelluloses". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI080.
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Ce projet s’est focalisé sur l’ajout de nouvelles propriétés à des papiers grâce à l’utilisation de nanocelluloses fonctionnelles. Ces nanocelluloses sont des nanoparticules extraites du bois qui peuvent être divisées en deux catégories : les nanofibrilles de cellulose (CNFs) et les nanocristaux de cellulose (CNCs). Ce travail s’est essentiellement penché sur l’utilisation des CNFs. Leur réactivité chimique a été utilisée afin de les fonctionnaliser avec des organotrialkoxysilanes. C’est aussi leur fort enchevêtrement ainsi que la grande viscosité de ces CNFs en suspension qui ont été utilisés afin de synthétiser des petites particules de silsesquioxane pour rendre le matériau final antimicrobien et (super)hydrophobe. Les connaissances obtenues à travers l’étude sur des films modèle de CNFs ont ensuite été appliquées au couchage du papier. Ces CNFs fonctionnelles ont donc été évaluées pour le développement d’un papier possédant une surface antimicrobienne, anti-adhérente, barrière aux graisses ou superhydrophobeThe aim of this work is to implement new properties to a paper based material via the use of functional nanocelluloses. Nanocelluloses are nanoparticles extracted from wood and distinguished in two categories: Cellulose Nanofibrils (CNFs) and Cellulose Nanocrystals (CNCs). This work has only been carried out with CNFs. The chemical reactivity of CNFs was used to functionalize them with organotrialkoxysilanes. The entangled network and highly viscous suspension of CNFs was also used to synthesize silsesquioxane particles with limited size to impart (super)hydrophobic and antimicrobial properties. Knowledge obtained through the study of model CNFs films was then applied to paper based material coating. The functional CNFs were evaluated for its use in an antimicrobial, anti-adherent, greaseproof or superhydrophobic paper surface
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Farmer, Catherine Elizabeth. "Surface Characterization of Siloxane, Silsesquioxane, and Maleic Anhydride Containing Polymers at Air/Liquid Interfaces". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32408.
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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
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Liu, Chang. "Giant Molecular Shape Amphiphiles Based on Polyhedral Oligomeric Silsesquioxane: Molecular Design and “Click” Synthesis". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367933162.
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CINA', Valerio. "SYNTHESIS AND APPLICATIONS OF NOVEL FULLERENES AND SILSESQUIOXANES BASED STRUCTURES". Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/395393.
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Gupta, A. "Development and characterisation of silsesquioxane-polycaprolactone nanocomposite scaffolds for use in small intestinal tissue engineering". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1306713/.
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Tissue engineering of small intestine aims to provide a cure to patients suffering from short bowel syndrome by increasing the absorptive surface through neo-intestinal mucosal tissue. So far, preliminary in vivo attempts by a research team in the USA have shown regeneration of neo-intestinal mucosa in rat models with some success; however experiments in this complex field of tissue engineering still remain in infancy and far from clinical use. A fresh perspective is required to further investigate all the three aspects of tissue engineering, namely, the polymer scaffold, the cell supply, and the biomolecules. The concept of nanocomposite polymer is rapidly emerging and has generated a lot of enthusiasm in tissue engineering due to their high surface to volume ratio and hence enhanced performance. This work was focussed to develop and characterise scaffolds for small intestinal tissue engineering using a new nanocomposite polymer of polycaprolactone and silsesquixane, developed in our laboratory. An in vitro study was also performed to test the scaffolds for cell viability and proliferation using rat’s intestinal epithelial cells. Our results have shown that biodegradable polycaprolactone-silsesquioxane nanocomposite can be fabricated in desired scaffold morphology using simple techniques like particulate leaching, and that it supports intestinal cell growth and proliferation. Future studies incorporating these scaffolds for in vivo use in animal models need to be carried out in order to investigate further about their ability to withstand natural forces within the abdomen, and whether they support cell growth based on principles of cell migration, before a more definitive and continuous cell supply is available in form of stem cells cued specifically to intestinal lineage.
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Qu, Haoran. "SOLUTION SELF-ASSEMBLY OF HEXAETHYLENE GLYCOL-FUNCTIONALIZED POLYHEDRAL OLIGOMERIC SILSESQUIOXANE (GPOSS) TETHERED WITH POLYSTYRENE CHAIN". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1486638275556455.
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McPherson, Melinda Kay. "The Reactivity of Chemical Warfare Agent Simulants on Carbamate Functionalized Monolayers and Ordered Silsesquioxane Films". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26793.
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The reactivity of chemical warfare agents (CWAs) and CWA simulants on organic and oxide surfaces is not currently well understood, but is of substantial importance to the development of effective sensors, filters and sorbent materials. Polyurethane coatings are used by the armed forces as chemical agent resistive paints to limit the uptake of CWAs on surfaces, while the use of metal oxides has been explored for decontamination and protection purposes. To better understand the chemical nature of the interactions of organophosphonate simulants with these surfaces, an ultra-high vacuum environment was used to isolate the target interactions from environmental gaseous interferences. The use of highly-characterized surfaces, coupled with molecular beam and dosing capabilities, allows for the elucidation of adsorption, desorption, and reaction mechanisms of CWA simulants on a variety of materials.
Model urethane-containing organic coatings were designed and applied toward the creation of well-ordered thin films containing carbamate linkages. In addition, novel trisilanolphenyl-polyhedral oligomeric silsesquioxane (POSS) molecules were used to create Langmuir-Blodgett films containing reactive silanol groups that have potential use as sensors and coatings. The uptake and reactivity of organophosphonates and chlorophosphates on these surfaces is the focus of this study.
Surfaces were characterized before and after exposure to the phosphates using a number of surface sensitive techniques including: contact angle goniometry, reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) measurements. In conjunction with surface probes, uptake coefficients were monitored according to the King and Wells direct reflection technique. The integration of these analytical techniques provides insight and direction towards the design of more effective chemical agent resistant coatings and aids in the development of more functional strategies for chemical warfare agent decontamination and sensing.Ph. D.
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Deng, Jianjun. "Interfacial Characterization of Polyhedral Oligomeric Silsesquioxane (POSS) Amphiphiles and Polymer Blends: Thermodynamics, Morphology, and Rheology". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27126.
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Over the past two decades one class of oligomers, polyhedral oligomeric silsesquioxanes (POSS), has attracted considerable attention because of their unique hybrid organic/inorganic molecular structures and nanoscopic sizes. While surface and interfacial properties may play a key role in many potential POSS applications, relatively little is actually known about the surface properties of POSS. This dissertation provides studies of the interfacial aspects of both POSS molecules and POSS/polymer blends at the air/water interface (A/W) through surface pressure-area per molecule (π-A) isotherm, Brewster angle microscopy (BAM), and interfacial stress rheometry (ISR) studies.
Results for POSS Langmuir thin films at A/W show that trisilanol-POSS derivatives are a new class of amphiphiles, that exhibit multiple phase transitions in going from traditional 2D Langmuir monolayers (1 POSS molecule thick) to various 3D multilayer films upon compression. With small length/diameter ratios and bulky shapes, the monolayer phase behavior and packing states of different POSS are simpler than the traditional rod-like lipids. Meanwhile trisilanol-POSS derivatives have very different collapse behavior and multilayer organization showing strong substituent effects even though they have similar molecular sizes. While trisilanolisobutyl-POSS (TiBuP) monolayers undergo collapse around π ≈ 18 mNm⁻¹ and form various ordered or disordered solid-like 3D aggregates at different compression rates, trisilanolcyclohexyl-POSS (TCyP) monolayers collapse into trilayers via instantaneous nucleation with hemispherical edge growth around π ≈ 3.7 mNm⁻¹. ISR results reveal three different non-Newtonian flow regimes that correlate with phase transitions in the Pi-A isotherms. Further symmetric compression after trilayer formation induces TCyP thin films to self-assemble into highly ordered crystalline-like hydrophobic multilayers (≈8 POSS molecule thick) with unique rod-like morphologies, which are dramatically different from –collapsed– morphologies seen in other systems.
By treating POSS derivatives as ideal nanofiller for studying confinement effects on filled polymer systems, amphiphilic poly(dimethylsiloxane) (PDMS) derivatives with different polar functional groups are studied as blends with TiBuP and octaisobutyl-POSS at A/W to resolve one of the key challenges for current nanocomposite applications: How to control nanofiller dispersion in polymer matrices? The results in this dissertation reveal that introducing polar groups into polymeric matrix polymers is a good way to control dispersion.Ph. D.
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Karabiyik, Ufuk. "Optical and thermal characteristics of thin polymer and polhedral oligomeric silsesquioxane (POSS) filled polymer films". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27713.
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Single wavelength ellipsometry measurements at Brewster's angle provide a powerful technique for characterizing ultrathin polymeric films. By conducting the experiments in different ambient media, multiple incident media (MIM) ellipsometry, simultaneous determinations of a film's thickness and refractive index are possible. Poly(tert-butyl acrylate) (PtBA) films serve as a model system for the simultaneous determination of thickness and refractive index (1.45 at 632 nm). Thickness measurements on films of variable thickness agree with X-ray reflectivity results. The method is also applicable to spincoated films where refractive indices of PtBA, polystyrene and poly(methyl methacrylate) are found to agree with literature values within experimental error. Likewise, MIM ellipsometry is utilized to simultaneously obtain the refractive indices and thicknesses of thin films of trimethylsilylcellulose (TMSC), regenerated cellulose, and cellulose nanocrystals where Langmuir-Blodgett (LB) films of TMSC serve as a model system.
Ellipsometry measurements not only provide thickness and optical constants of thin films, but can also detect thermally induced structural changes like surface glass transition temperatures (Tg) and layer deformation in LB-films. Understanding the thermal properties of the polymer thin films is crucial for designing nanoscale coatings, where thermal properties are expected to differ from their corresponding bulk properties because of greater fractional free volume in thin films and residual stresses that remain from film preparation. Polyhedral oligomeric silsesquioxane (POSS) derivatives may be useful as a nanofiller in nanocomposite formulations to enhance thermal properties. As a model system, thin films of trisilanolphenyl-POSS (TPP) and two different molar mass PtBA were prepared as blends by Y-type Langmuir-Blodgett film deposition. For comparison, bulk blends were prepared by solution casting and the samples were characterized via differential scanning calorimetry (DSC). Our observations show that surface Tg is depressed relative to bulk Tg and that magnitude of depression is molar mass dependent for pure PtBA films. By adding TPP as a nanofiller both bulk and surface Tg increase. Whereas, bulk Tg shows comparable increases for both molar masses, the increase in surface Tg for higher molar mass PtBA is greater than for lower molar mass PtBA. These studies show that POSS can serve as a model nanofiller for controlling Tg in nanoscale coatings.Ph. D.
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Jiang, Jing. "Giant Shape Amphiphiles Based on Polyoxometalates (POMs)-Polyhedra Oligomeric Silsesquioxane (POSS) Hybrids: Synthesis and Characterization". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366811690.
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Lee, Byoung-Jo. "Nucleating Agent-Assisted Preparation of Polypropylene (PP)/Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites and Their Characterization". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1247779040.
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Yue, Kan. "Design, Synthesis and Self-Assembly of Shape Amphiphiles Based on Polyhedral Oligomeric Silsesquioxane-Polymer Conjugates". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384817970.
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Pu, Fan. "The Ionic Effect on the Self-Assembly of Polyhedral Oligomeric Silsesquioxane Macroions in Dilute Solutions". University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1426507842.
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