The adsorption isotherms of polyethylene glycol (I), polypropylene glycol (II), and ethylene oxide-propylene oxide block copolymer Pluronic L64 (III) on various active C with different degree of silanization were Langmuir-type. The limiting adsorption of I with different mol. wt. onto the same C was constant; the mol. areas at limiting adsorption decreased linearly with increasing no. of ethylene oxide units, showing a slope which decreased sharply with increasing silanization time. The results were explained by the orientation of CH2CH2 groups of I at the solid surface. The limiting adsorption, the mol. area at limiting adsorption, and the adsorbed layer thickness indicated that II did not lie flat on the active C surface. The adsorption of I onto methylated silica gel was low and that of II on to methylated silica gel decreased with increasing mol. wt. The adsorption of III onto methylated silica gel was higher than that onto hydrophilic silica gel.

Key words: WATER, BLOCK COPOLYMER, POLYETHYLENE OXIDE, PROPANEDIOL P, METHYLATION, SILICA GEL, ETHYLENE OXIDE, SILYLATION, EPOXYPROPANE, SURFACES ADSORPTION