Unperturbed chain dimension of poly(vinyl chloride) polymerized at different temperatures

For poly(vinyl‐chlorides) polymerized at various temperatures in a range of −15 to +50°C., the Θ‐point was determined in the system tetrahydrofuran/water at 30°C., according to the method proposed by ELIAS, and the unperturbed chain dimension in the Θ‐solvent was investigated in relation to the structural factors, such as branching and stereoregularity of the polymer, as a function of the polymerization temperature. The unperturbed chain dimension of the polymer polymerized at lower temperature was found to be larger than that polymerized at higher temperature. This result is interpreted by that poly(vinyl chloride) is more syndiotactic and less branched with lower polymerization temperature, and that increase in the syndiotacticity leads to the increase of unperturbed dimension more effectively than the effect of short chain branching.