STUDIES ON THE INTERNAL SURFACE OF POROUS-GLASS AND CHEMICAL MODIFICATION THEREOF

Porous glass powders (CPG) prepared by spinodal phase separation, and silica gel showed IR spectra (Figs. 3 and 4) typical of so called isolated silanol hydroxyl groups on glass surface, when they were dehydrated by heating in dessicated air stream. Porous glass (SPG) prepared from volcanic sand as silicon source, which contains alminium up to 15% as A12O3 (Table 2), adsorbed water more quickly than CPG (Fig. 8), and it was fairly difficult to get simplified surface structure uniquely consisting of silanol hydroxyl groups, without any extraction of aluminium (Figs. 2 and 6). Surface density of aminoalkyl groups on the surface of porous glasses, either of CPG or of SPG which was dehydrated and followed by chemical modification with (aminoalkyl) tri-methoxysilane, was estimated according to the method of Gisin who had used it for amino-methylated polystyrene in Merrifield's method of sqlid-phase peptide synthesis. The surface densities of amino groups were about 2µmol.m-2 for both CPG and SPG as shown in Fig. 10 and 11. The value corresponds to 1/3 of the density of silanol hydroxyl groups, 7~9 µmpl. m_z, estimated from the data of water elimination measurements of porous glasses (Table 4) by assuming the elimination of a water molecule from every two hydroxyl groups. © 1990, The Chemical Society of Japan. All rights reserved.