Estudio por espectroscopía infrarroja de la reacción de hidrólisis y policondensación del IEOS en presencia de PDMS

Abstract

In this work, we have studied, by FT-IR Spectroscopy, the influence of the molecular weight of organic polymers (polydimethylsiloxane, PDMS) in the hydrolysis and polycondensation reactions of tetraethylortosilicate (TEOS) in acid medium. Following of the bands located at 880,1180 and 850 cm-1, the hydrolysis and selfcondensation of TEOS process and copolymerization between TEOS and PDMS respectively can be studied. The rates of hydrolysis and self-condensation of TEOS are not affected by the presence of the polymer. However, the reaction of copolymerization between TEOS and PDMS decreases when the molecular weight of polymer increase, and this is due to both the diferences in the concentration of silanol end groups of polymer and polymer viscosity. The materials obtained from high molecular weight (18000 and 26000 g/mol) have gelification times as TEOS. On the other hand the gelification time decreases when polymers of lower molecular weight (550 and 1700 g/mol) are used. This work shows that FT-IR Spectroscopy can be applied to investigate the sol-gel reactions.