Siloxane organic hybrid material

Thus the sol-gel methodology is an alternative to classical thermodynamic routes for the synthesis of solids. It is also evident that the preparation of the solids through Chimie Douce bridges molecular chemistry and solid state chemistry. This chapter will be focused on material prepared by the sol-gel process, where an organic part is associated with a silica or siloxane Si—O—Si network. Two types of organic-inorganic hybrid materials can be prepared by the sol-gel process and are completely different the nanocomposites and the nanostructured hybrid materials6-9. 

Cyclic siloxanes are one of the important class of inorganic-organic hybrid compounds, which have often been used to improve the properties of the materials [23-25],... 

Dragan, E. S. Cazacu, M. Nistor, A., Ionic Organic/Inorganic Materials. III. Stimuli Responsive Hybrid Hydrogels Based on 01igo(N,N-dimethylamino-ethylmethacrylate) and Chloroalkyl-Functionalized Siloxanes. J. Polym. Sci., Part A Polym. Chem. 2009,47, 6801-6813. 

Yamada, N. Yoshinaga, L Katayama, S., Formation Behavior and Optical Properties of Transparent Inrganic-Organic Hybrids Prepared from Metal Alkoxides and Polydimethylsiloxane. J. Sol-Gel Sci. Technol. 2000,17,123-130. Lebeau, R. Maquet, J. Sanchez, C. Beaume, F. Laupretre, F., Structural and Dynamical Studies of Hybrid Siloxane-Silica Materials. J. Mater. Chem. 1997,... 

Materials related to polysiloxanes are silsesquioxanes (Scheme 1) (2). These cubic siloxane molecules have been produced with a number of functional species such as styrene and methacrylate moieties protruding from one corner of the structure (3, 4). Classic free radical polymerization of these molecules has been shown to produce an inorganic / organic hybrid homopolymer. Furthermore, cubes have been synthesized with pendant silyl hydrido and silanolate moieties which can be used for further functionalization (5). 

Of special interest are the concept of structure-directed function of hybrid materials and how to control their build-up from suitable units by self-organization. Toward this objective, new functional hybrid membrane materials can be anticipated that form selective patterns so as to enable efficient translocation events. This implies the search for hybrid soUd systems in which the molecular recognition-driven transport function could be ensured by a well-defined incorporation of specific receptors, covalently linked in a dense siloxane matrix. 

Therefore, numerous siloxane-based hybrid organic-inorganic materials have been developed in the past few years. This development yields many interesting new materials, with improved mechanical properties timable between those of glasses and those of polymers. Sol-gel processed hybrid materials such as, optical devices, new sensors and biosensors, new catalysts or membranes have been reported to have high efficiencly, good selectivity and stability (Lebeau, 1999). 

Atsushi Morikawa studied organic materials science at the Tokyo Institute of Technology. In 1992 he obtained his doctor s degree on siloxane dendrimers and polyimide-silica hybrid materials by sol-gel method. After a two-year spell as a research engineer at Asahi Chemical Company, he transferred to the Faculty of Engineering at Ibaraki University to continue his research on polyfether ketone) dendrimers and polyimides. 

Other chemical modifications include the introduction of siloxane, reaching an organic-inorganic hybrid material [43, 44]. It can be added in the polymer backbone or also as pendant group. This approach consists in the generation of interpenetrating networks which increase the thermal stability of the material [45]. 

---