Synthesis of inorganic-organic hybrid materials from TEOS, TBT and PDMS

Inorganic-organic hybrid materials have been synthesized by reaction of tetraethoxysilane (TEOS), titanium tetrabutoxide (TBT) and silanol-terminated polydimethylsiloxane (PDMS). The hydrolysis and polymerization reactions of TEOS and PDMS in presence of TBT have been followed by means of FT-IR spectroscopy. Hydrolysis reactions have been characterized by Si-O-C and Ti-O-C bonds and polymerization reactions by Si-O-Si, Si-O-Ti and Ti-O-Ti bonds. The instantaneous hydrolysis of TEOS, the condensation reactions between Si-OH groups forming crosslinked and linear Si-O-Si structures and the copolymerization reactions between Si-OH groups and PDMS molecules have been observed. The reaction between Ti-OH and Si-OH groups or PDMS gives Si-O-Ti bonds. Si-O-Ti bonds are formed during the addition step of TBT and they show a decrease along the reaction time up to gelling. By another hand, the concentration of crosslinked and linear Si-O-Si structures depend on the TBT concentration. High TBT concentration favors the formation of crosslinked chains. TBT influences the hydrolysis and copolymerization reactions between hydrolyzed TEOS and PDMS molecules.