Polymer conformation and viscometric behaviour-II. Conformational transition in (benzyl methacrylate-cyclohexylmethyl methacrylate) copolymers in dilute solution

Copolymers of benzyl methacrylate with cyclohexylmethyl methacrylate were synthesized. The reactivity ratios of the monomers were established. Osmotic and viscometric measurement were made in isobutyl methyl ketone (IMK) and toluene at 25° for a copolymer of equimolar composition. The viscometric relations in both solvents were established. Viscometric studies of fractions of the 1:1 copolymer show discontinuities in the intrinsic viscosity [η] as a function of temperature and sharp changes in the unperturbed dimensions of the chain in IMK. Variations of the refractive index increment in the same temperature range were observed. This behaviour is interpreted as a conformational transition of the copolymer chain. The results are discussed in relation to the behaviour of the homopolymers in the same solvent.