Interfacial interactions and their influence to phase behavior in poly(vinyl pyrrolidone)/silica hybrid materials prepared by sol-gel process

In this research, hybrid materials constructed by poly(vinyl pyrrolidone) (PVP) and inorganic tetraethyloxysilane (TEOS) or methyltriethyloxyslane (MTEOS) were synthesized via sol-gel process. From visual and scanning electron microscopic (SEM) observation, inorganic silicate was not separated from the organic phase in PVP/MTEOS hybrid system and in PVP/TEOS hybrid system with 20 wt.% or less TEOS content. With 40 wt.% TEOS content, microphase separation occurred; furthermore, phase separation and phase inversion can be observed with TEOS content increased to 60 wt.% or more in PVP/TEOS hybrid system. These results were confirmed by the variation of glass transition behavior. From infrared spectra analysis, hydrogen bonds were formed in both PVP/MTEOS and PVP/TEOS hybrid systems. However, higher hydrogen bonding interaction in PVP/TEOS did not induce higher compatibility as compared to PVP/MTEOS. This was due to the greater non-polar interaction between methyl group of MTEOS and polymer backbone in PVP/MTEOS hybrid system. (C) 2004 Elsevier B.V. All rights reserved.