New Condensation Polymer Precursors Containing Consecutive Silicon Atoms—Decaisopropoxycyclopentasilane and Dodecaethoxyneopentasilane—And Their Sol–Gel Polymerization

Abstract

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.

Keywords

• sol–gel precursor
• condensation polymer
• alkoxycyclopentasilane
• alkoxyneopentasilane
• porosity
• polysilane
• polysiloxane
• oxidation of Si–Si bond