Anionic polymerization of p‐diisopropenylbenzene in tetrahydrofuran: Reactivity of pendent double bond

Anionic polymerization of p‐diisopropenylbenene was found to be an equilibrium polymerization not only with respect to the monomer but also with respect to the pendent double bond. The polymerization was studied from kinetic as well as from the thermodynamic point of view, especially to ascertain the reactivity of the pendent double bond as compared with the double bond of monomeric analog. It was shown that the crosslinking rate constant of the pendent double bond is lower by about three to four orders than the propagation rate constant of the monomeric analog. The rate of cyclization was also very slow. From the equilibrium, the heat and entropy of polymerization of the monomer were determined as ΔHss = −5.8 kcal/mole and ΔSss = −18.0 cal/deg mole, respectively, and those of the pendent double bond as ΔHss = −6.3 kcal/mole and ΔSss = −27.8 cal/deg mole. When compared with the polymerization of α‐methylstyrene, the low thermodynamic polymerizability of the pendent double bond is attributed to the low heat of polymerization, which may arise from the large steric hindrance of neighboring groups. The effect is much smaller for the equilibrium than for the rate of polymerization, however.