Synthesis of (styrene‐p‐chlorostyrene) tri‐block copolymers and their properties in dilute solutions

Abstract

AbstractTwo series of well‐characterized (styrene‐p‐chlorostyrene) tri‐block copolymers of BmAnBm‐ and AmBnAm‐types (A: styrene monomeric unit, B: p‐chlorostyrene monomeric unit. n = 2m denotes the number of units) were synthesized by anionic polymerization technique. Their intrinsic viscosities in toluene, 2‐butanone, and cumene were studied over a wide range of molecular weights. The data were analyzed on the basis of two‐parameter theories. The unperturbed dimensions of the block copolymers are expressed by those of the parent homopolymers and the composition. The conformational behaviours of the BmAnBm and AmBnAm copolymers are similar in the non‐selective solvents, toluene and 2‐butanone, whereas in the selective solvent, cumene, which is a Θ solvent for poly‐p‐chlorostyrene and a good solvent for polystyrene, a molecule of the AmBnAm copolymers takes a more extended chain conformation and a greater value of the longrange interaction parameter than the BmAnBm copolymers of the same composition. However, an anomaly which suggests “Intrachain phase separation” was not observed in the viscosity behaviours of the block copolymers in cumene as well as in toluene and 2‐butanone.