Association of block copolymers in selective solvents 2. Viscosity, diffusion and light‐scattering measurements on hydrogenated poly(styrene‐isoprene) in trans‐decalin/decane mixtures

The association of a hydrogenated poly(styrene‐isoprene) block copolymer has been studied in mixtures of a selective (decane) and a non‐selective solvent (trans‐decalin). Viscosity, diffusion and light‐scattering studies were made within the temperature range of 25–100°C. Relatively small, compact micelles with a rather monodisperse distribution are found at low temperatures and high decane concentrations; very large, polydisperse associates are formed at intermediate decane concentrations and also at increasing temperature from the compact micelles prior to complete dissociation. These large particles have no particular effect on the inherent viscosity, which shows a gradual, continuous decrease as the polymer passes from the associated to the dissociated state. The association also gives rise to drastic changes in the UV absorption of the polystyrene part of the polymer. Kinetic experiments indicate a time scale of the order of ten seconds for the association‐dissociation transition.