SURFACE SCIENCE AND STABILITY OF NETWORKS PREPARED FROM HYDROXY-TERMINATED POLYDIMETHYLSILOXANE AND METHYLTRIETHOXYSILANE

Polydimethylsiloxane (PDMS) hybrid networks have been prepared by the reaction of PDMS(OH)(2), average molecular weight 26 x 10(3), 43.6 x 1 0(3) and 58 x 10(3), and methyltriethoxysilane (MeTEOS, 10-60 wt%) usi ng a dibutyltin dilaurate or dibutyltin diacetate catalyst. By hydroly sis and homo- and cocondensation, MeTEOS forms a siliceous domain (MeS D) and acts as a crosslinker for the PDMS domain, Kinetic studies show ed that high MeTEOS and catalyst concentrations and reduction of free surface area favor fast gelation and efficiency in converting MeTEOS t o the MeSD, Under the water-sparse conditions utilized, cure was slow and substantial evaporative loss of MeTEOS occurred. (C) 1998 John Wil ey & Sons, Ltd.