Seguimiento por espectroscopia infrarroja (FT-IR) de la copolimerización de TEOS (tetraetilortosilicato) y PDMS (polidimetilsiloxano) en presencia de tbt (tetrabutiltitanio)

Hybrid materials have been prepared in this work through the reactions of Si and Ti alkoxides (TEOS and TBT, respectively) and polydimethil siloxane (PDMS). These reactions have been studied by means of FT-IR spectroscopy during the whole reaction time. The hydrolysis of TEOS molecule has been followed by the 880 cm^-1 band, and the self-condensation reactions through the 1180 and 1150 cm^-1 bands. Polycondesation reaction between Si-OH groups and PDMS molecules has been followed by the 850 cm^-1 band. On the other hand, the hydrolysis reaction of TBT and the self-condensation of Ti-OH groups have been followed by the 1130 and 770-510 cm^-1 bands, respectively. Finally the condensation reaction between Si-OH and Ti-OH groups have been studied by the 936 cm^-1 band. Results have shown that hydrolysis and condensation reactions are depending on TBT concentration. The formation of Si-O-Si cross-linked structures increases with the TBT concentrations in the reaction. The self-condensation reaction of Si-OH grups or Ti-OH grous is very reapid forming Si-O-Si and Ti-O-Ti bonds, respectively. However, the Si-O-Ti bonds which are formed during the first moments of reaction are also rapidly broken due to H₂O molecules or the reaction medium. The evolution of PDMS linear and cyclic molecules is also studied.