Kinetic and thermodynamic characteristics of anionic living-equilibrium polymerization for (p-Isopropenylphenethyl)poly(α-methylstyrene) macromonomer

The anionic living-equilibrium polymerization (ALEP) of (p-isopropenylphenethyl)poly(α-methylstyrene) macromonomer (PMStM) was studied: PMStM was simultaneously purified and initiated above a ceiling temperature (Tc) and then propagated below Tc. Three PMStMs (Mn = 1.77 × 103, 3.65 × 103, and 5.36 × 103) were prepared by the coupling of poly(α-methylstyryllithium) with p-isopropenylphenethyl chloride, and were polymerized to produce polymacromonomers, (PMSt)m (m = 9.5, 4.1, and 3.5) by n-BuLi in d8-THF at temperatures below −10 °C under high vacuum via ALEP. From kinetic studies using a 1H NMR technique, the propagation rate constant (0.240, 0.110, and 0.079 l mol−1 s−1) at −78 °C was found to be proportional to a reciprocal of Mn of PMStM, and its Mn dependence was discussed based on a simple diffusion-controlled theory. The thermodynamic characteristics of ΔHMSt (−7.48, −6.73, and −3.82 kJ mol−1) and ΔSMSt (−26.8, −24.1, and −13.7 J mol−1 K−1) were determined from a kinetic analysis, and their Mn dependence was also discussed. The TC values for the three PMStM, including α-methylstyrene, were found to be the same (6.0 °C).