| Abstract: | The conformational behaviour of polystyrene-block-polybutadiene-block-polystyrenes, ABA-type triblock copolymers, with 50 wt.-% of A blocks were studied by light scattering, viscometric and osmometric methods over a wide range of molecular weight. Unperturbed dimensions were found directly by light scattering in the θ solvent methyl isobutyl ketone and also estimated by extrapolation methods from intrinsic viscosity and osmometric results in toluene, a thermodynamically good solvent. Osmometric and viscometric results showed that the block copolymers form a Gaussian coil in toluene, whereas light scattering results indicated some segregation of blocks for a low-molecular-weight sample in the θ solvent. |
