Polymerization of α-Methylstyrene in Cyclohexane with Potassium as Initiator. IV. Thermodynamic Study and Gel-Permeation Chromatographic Analyses of the Polymers

Abstract

Polymerization of α-methylstyrene in cyclohexane containing traces of tetrahydrofuran (THF) has been carried out at 40°C with potassium as initiator. The conversion of monomer to polymer was very slow, and a solution with [M]₀ of 5.15 mole/ liter, carrying 0.110 mole/liter of the living ends [LE], required two months to reach a stationary state. The gel-permeation chromatographic (GPC) analyses of these polymers showed them to have multimodal distributions which could be split into components D+A, B, and C similar to those found for poly-α-methylstyrene prepared in THF and α-dioxane as solvents. Furthermore, under identical conditions of [M]₀ and [LE], the GPC distributions of poly-α-methylstyrene prepared in cyclohexane, p-dioxane, and THF were the same, in spite of their different dielectric constants. Under identical conditions of [M]₀ but with different [LE], the effect of excessive [LE] on the GPC distributions of the polymers prepared in cyclohexane was not limited to the component D+A as was the case when THF or p-dioxane were the solvents, but also on the component C which increased its contribution [P]_e to the polymer.