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Synthesis of Organosilica Films Through Consecutive Sol/Gel Process and Cationic Photopolymerization

“…This aspect is of high importance since many studies reported that epoxy ring opening was likely to take place under acid aqueous conditions. [28,[40][41][42][43] Epoxides can indeed possibly react with water under specific acid conditions to form diols or alkoxy ether terminal groups, preventing their polymerization. In order to avoid such unproductive ring opening reactions, Crivello et al used, for instance, weakly acidic ion exchange resins [12] instead of conventional mineral acids.…”

Fluorescence Spectroscopic and Atomic Force Microscopic Studies on the Microstructure of Polyimide/Silica-Titania Ternary Hybrid Composites

“…Some structure is overlapped with other structure, while some structure persists its own characteristics, depending on the reactivity (relative rate of hydrolysis and condensation during sol-gel reaction) of Si-O-Si, Ti-O-Ti and Si-O-Ti-O-Si bonding as well as the interaction between PI matrix and the inorganic particles. The homo-and hetero-condensation reactions of Si-alkoxide and/or Ti-alkoxide during sol-gel processing were systematically investigated by Hoebbel, et al 24,25 As the amount of Ti is increased in the Si-Ti system, any of the structures due to lots of different kinds of particles affect competitively and cooperatively on the photophysical behavior of the composite systems. Then, it may be considered that no peculiar structure is predominant and instead the local structure environment combines a variety of complex morphology, which gives a single broad and structureless emission peak.…”

Crystallization in hybrid organic-inorganic materials through self-organization from 3-glycidoxypropyltrimethoxysilane

“…A large variety of catalysts have been used for the opening of the epoxy groups, acid 16) and basic 19), 34) catalysts, photocatalysts. 35) 1-methylimidazole 19) (MI) and (£-aminopropyl)triethoxysilane (APTES) 36) are examples of basic catalysts, while Lewis acids, such as titanium, 37) zirconium 38) and aluminium alkoxides 39) are the most common acid catalysts. In particular, the transition metal alkoxides are very important in the solgel synthesis of GPTMS hybrids because they modify the inorganic network giving rise to the formation of a mixed oxide inorganic structure.…”