Steric stabilization of polymer suspensions in hydrocarbon media by adsorbed layers of graft copolymers

Sterically stabilized dispersions of fine polymer particles in hydrocarbon media have been used for the study of the adsorption of amphipathic graft copolymers at polymer/hydrocarbon interfaces. The amount of graft copolymer adsorbed on the particle surfaces during the dispersion polymerization has been determined for a number of polymer substrates, over a range of particle sizes, and at different stabilizer concentrations. From these results the average surface spacing of the solvated component of the adsorbed graft copolymer has been calculated for solvated groups of low, medium and high molecular weight. In a limited number of cases the hydrodynamic steric barrier thickness has also been measured. These stabilizer spacing and barrier thickness values are compared with the dimensions of the solvated groups in free solution and the nature of the packing of these groups on the particle surface is discussed. Anomalous results obtained in a few cases are shown to be due to the mechanism of particle growth.