Synthetic pathway to functional block copolymers with pendent triphenylamine and ethynylpyridine: Effect of countercation on anionic polymerization behavior

The block copolymerization of 4,4′‐vinylphenyl‐N,N‐bis(4‐tert‐butylphenyl)benzenamine ( A ) with 2‐(2‐(4‐vinylphenyl)ethynyl)pyridine ( B ) was performed using sec‐butyllithium (s‐BuLi) as an initiator in the absence and presence of potassium tert‐butoxide (KOBu^t) in tetrahydrofuran (THF) at ?78 °C. The block copolymerization was not successful in the absence of KOBu^t, whereas the well‐defined diblock copolymer (poly( A ‐b‐ B )) containing pendent triphenylamine and ethynylpyridine was successfully synthesized in the presence of excess KOBu^t due to the change in the countercation from Li⁺ to K⁺ and the suppression of ion dissociation by the salt common effect. The poly( A ‐b‐ B )s had predictable molecular weights (M_n = 4,900–20,000 g/mol) and narrow molecular weight distributions (M_w/M_n = 1.13–1.15). In addition, the resulting block copolymer showed good solubility and excellent thermal properties. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4233–4239