Effect of isomeric pyridine moieties in ethynylstyrene derivatives on their anionic polymerization

The anionic polymerization behaviors of ethynylstyrene derivatives containing isomeric pyridine moieties, 2‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( A ), 3‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( B ), and 4‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( C ), were investigated in the identical conditions. The anionic polymerization of A – C was performed with (diphenylmethyl)potassium (Ph₂CHK) in tetrahydrofuran (THF) at ?78 °C. The polymerization of A proceeded quantitatively at –78 °C for 4 h, and the resulting poly( A ) possessed predictable molecular weights (M_n = 3300–68,500) and narrow molecular weight distributions (MWDs) (M_w/M_n = 1.04–1.11). In contrast, the anionic polymerization of B was not performed at –78 °C for 4 h due to the occurrence of side reactions. The monomer B was quantitatively recovered after the reaction. In the polymerization of C performed at –78 °C for 6 h, observed M_n values of the resulting poly( C ) were in good agreement with calculated molecular weights based on monomer to initiator ratios, but the MWDs were somewhat broad (M_w/M_n = 1.23–1.31). To estimate the reactivity of A and to characterize its living nature, the block copolymerization of A with 2‐vinylpyridine (2VP) and methyl methacrylate (MMA) was performed. The well‐defined block copolymers, poly(2VP)‐b‐poly( A ) and poly( A )‐b‐poly(MMA), were successfully synthesized without any additives. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011