New condensation polymer precursors containing consecutive silicon atoms- decaisopropoxycyclopentasilane and dodecaethoxyneopentasilane-and their sol-gel polymerization

The sol-gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon-organic composites. The development of new sol-gel precursors is very important for obtaining new types of sol-gel products. New condensation polymer precursors containing consecutive silicon atoms-decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)-were synthesized for the preparation of polysilane-polysiloxane material. The CPS and NPS xerogels were prepared by the sol-gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N₂ physisorption measurements (Brunauer-Emmett-Teller; BET and Brunauer-Joyner-Halenda; BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol-gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane-polysiloxane.