Control of pore size distribution of silica gel through sol-gel process using water soluble polymers as additives

Abstract

To control the pore size distribution of silica gel, several kinds of water soluble polymers were added in the sol-gel process starting from tetraethyl orthosilicate. The polymers employed here were classified into three groups. The first group comprised uncharged polymers such as polyvinyl alcohol and polyethylene glycol, which affected only the amount of micropores and small mesopores (<20 nm). The second group comprised charged polymers (polyelectrolyte) such as polyacrylic acid (anionic) and a quaternary salt of polyethylene imine (cationic), which significantly increased the number of larger mesopores (>20nm). The third group comprised proteins such as lipase and albumin and decreased the number of micropore and mesopores and greatly increased the number of macropores. The results could almost be explained in terms of the principal effects of the polymers on a process of sol particle growth.