Solution properties of copolymer of p‐chlorostyrene and methyl methacrylate

The monomer reactivity ratios in the free radical copolymerization of methyl methacrylate and p‐chlorostyrene were obtained and an azeotropic copolymer containing the 0.484 mole fraction of methyl methacrylate was prepared. The copolymer was fractionated into nine fractions, which on the basis of their chlorine content and specific refractive index increments, were found to be homogeneous in their chemical composition. The solution behaviour of these fractions was examined by viscosity, osmotic pressure and light‐scattering techniques. The weight‐average molecular weights obtained in dioxane, chloroform and 78:22 v/v mixture of trans‐decalin and trichloro ethylene (Θ solvent at 22.3°C) were found to be identical but those obtained from benzene were as much as 80% higher, depending on the molecular weight. The data were treated by the method of STOCKMAYER and BENOIT and the deviation and square‐deviation of the chemical composition was obtained as zero and proportional to M1.5, respectively. The value of exponent “a” in the KUHN‐HOUWINK equation[η] = KMa obtained by use of the number‐average molecular weight and corrected weight‐average molecular weight, was identical but the apparent weight‐average molecular weights obtained in benzene gave a low value of “a” confirming the applicability of the STOCKMAYER‐BENOIT relationships. The value of the constant K obtained for the copolymer in the theta solvent was 6.4·10−4 compared with 4.9·10−4 and 5.0·10−4 obtained for poly(methyl methacrylate) and poly‐p‐chlorostyrene, respectively, indicating a 10% higher dimension for the copolymer.