CONFORMATIONAL BEHAVIOR OF (STYRENE-PARA-CHLOROSTYRENE) TRIBLOCK COPOLYMERS IN DILUTE-SOLUTIONS .2. TEMPERATURE-DEPENDENCE OF CONFORMATIONAL BEHAVIOR IN A SELECTIVE SOLVENT

Intrinsic viscosity, osmotic second virial coefficient and light scattering of the BmAnBm and AmBnAm copolymers (A, styrene monomeric unit; B, p-chlorostyrene monomeric unit, m and n denote the number of units) in cumene which is a good solvent for polystyrene but a θ solvent for poly(p-chlorostyrene) at 59.0°C, were studied over the temperature range 65° to 15°C. The results suggested that conformational transition from a random coil form to a segregated form occurs at a critical temperature which appears to be in the range 40° to 30°C, depending on the composition, molecular weight and structure of the block copolymers; the θ condition could not be attained by cooling the block copolymer solutions, and micelle formations due to intermolecular associations were found in some cases below the transition temperature. © 1979.