Chain dimensions of polystyrenes diluted with low molecular weight homologues

Abstract Chain dimensions of polystyrenes diluted with benzene, styrene monomer, and low molecular weight homologues were measured by small-angle neutron scattering. Polystyrenes were confirmed to be expanded in monomer and in the homologues having sufficiently low molecular weights when polymer concentrations are low, and the concentration dependence of the expansion factor gets weaker with increasing degree of polymerization, N S , of “diluent”. The critical N S value, N S,c , which is the maximum value to give the excluded volume effects, is much higher than the theoretical prediction, N S,c ≈ N L 1/2 , where N L is the degree of polymerization of the “solute” polymer.