Adsorption of poly(vinylimidazoles) onto silica surfaces

The solution properties (proton uptake and viscosity) and the adsorption of poly(vinylimidazole) (PVI) and partially quaternized poly(vinylimidazoles) (PQPVI 0 to 52%) onto silica are studied at pH 3, 5 and 7, at ionic strengths of 10(-3) to 10(-1) M. For all pH values, adsorption peaks for PQPVI are between 2 and 4%, where electrophoretic mobility is minimum. Adsorption decreases with pH and increases with salinity. Results compare well with previous data at pH 10 [Bohmer et al., Colloids Surf. A 99 (1995) 53]. Polymer uptake results from specific bonds between acidic silica and basic imidazole. However, polymer uptake is strongly altered by electrostatic interactions. The charge balance at the isoelectric point shows that the adsorbed layer enhances surface ionization through charge compensation. (C) 1998 Elsevier Science B.V. All rights reserved.