CHEMICAL MODIFICATION OF SILICA-GELS

Highly porous pure and polyethyleneglycol (PEG)-doped silica gels have been prepared from tetraethyl orthosilicate (TEOS) in ethanol using N H4OH base-catalysis. Addition of PEG to the SiO2-system increases the average particle size and most frequent pore diameter of the resultant gels while their total surface area decreases. The viscosity of the s ol increases with PEG concentration and passes through a maximum with increasing molecular weight at PEG 200. Results obtained indicate a de finite interaction of the polymer with SiO2 and that this interaction is not as a result of direct formation of Si-O-C linkage, but is more likely to be due to hydrogen bonding between the hydrated PEG and the Si-O-Si network. Structure-process correlations are considered.