Vinyl polymerization. VI. Dilute solution properties of 1:1 Poly (styrene-co-ethylmethacrylate)

Abstract

1:1 Poly (styrene-co-ethylmethacrylate) (PSEM) was prepared by bulk polymerization and fractionated using methylethyl ketone/petroleum ether system. IR and NMR analyses of the copolymer substantiated the composition kinetically expected. As the composition heterogeneity of the compolymer was narrow, the characterization of the copolymer was effected in a single solvent by light scattering as well as viscosity measurements at 35°C. The molecular weight dependence of [η], the limiting viscosity number; (r̅²)_w^½, therms end to end distance and A₂ the second virial coefficient were established. The solvent ethylacetate was found to be thermodynamically more ideal for PSEM, than for polyethylmethacrylate. In an attempt to evaluate K, the Flory's constant, application of various methods appeared to give almost similar values. In order to explain the low value of φ, the Flory's universal parameter, rough estimates of (r̅²₀)^½, the unperturbedrms end to end distance; b, the statistical chain element;q, the persistence length and r̅²₀/lr̅_max, the semiflexibility parameter were also made.