Association of block copolymers in selective solvents, 1. Measurements on hydrogenated poly(styrene‐isoprene) in decane and in <i>trans</i>‐decalin

Abstract

Abstract The dilute solution properties and association of hydrogenated poly(styrene‐isoprene) two‐block copolymers in decane and trans ‐decalin have been studied by means of viscosity, diffusion and light‐scattering measurements. Data were obtained for two samples with molecular weights of 48 000 and 80 000, and both with a styrene content of 38%. In trans ‐decalin the normal behaviour of a non‐associating polymer is found. Association occurs in decane with the formation of compact micelles, composed (at ambient temperatures) of about 80 molecules. In contrast to what is observed in other associating two‐block systems, the transition to the completely dissociated state at elevated temperatures causes a drop of the intrinsic viscosity. Moreover, and this is not evident from the viscometric results, the diffusion and light scattering studies reveal that in the intermediate region between association and dissociation another kind of structure with very large dimensions is formed that exists over an extended temperature range. A qualitative description of the observed phenomena is given.