BLOCK COPOLYMER ADSORPTION AND STABILIZATION OF COLLOIDS

The self-consistent field model of Evers et al. for the adsorption of block copolymers from solution is briefly reviewed and illustrated with simple examples for monomer and dimer adsorption. Equations for the free energy of interaction between surfaces bearing adsorbed layers of block copolymers are given, both for full equilibrium and for restricted equilibrium. The adsorption and stabilization behaviour of diblock copolymers is compared with that of triblock copolymers with an adsorbing middle block. It is shown that diblock copolymers give thicker adsorbed layers than triblock copolymers with the same length of the soluble blocks. If the adsorption energy of the adsorbing block is high enough, the structure of the adsorption layer and the stabilizing action of diblock copolymers are about the same as for end-grafted chains with the same coverage and length of the stabilizing hairs. There exists an optimum block length ratio for diblock copolymers, for which the adsorbed amount and polymer-induced repulsion between colloidal particles are a maximum. © 1990.