The anionic polymerization of 1,4-divinylbenzene (1) and its ortho (2) and meta isomers (3) were studied under a variety of conditions. One of the two vinyl groups of 1 was selectively and exclusively polymerized in a living manner by the addition of a suitable additive under the conditions of −78 °C for 1 min and −95 °C for 30 min. Under such conditions, the unwanted addition reaction of the chain-end anion to the pendant vinyl group was almost suppressed and soluble polymers with predictable molecular weights of up to 60 500 g/mol and narrow molecular weight distributions (M w/M n < 1.05) were quantitatively obtained. The amount of dimerized chain produced by the addition reaction was negligible or very small (<5%). The effective additives in the polymerization involve potassium alkoxides and phenoxides, derived from tert-butyl alcohol, sec-butyl alcohol, 2,4-dimethyl-3-pentanol, 1-methylcyclohexanol, 1:2,5:6-di-O-isopropylidene-α-d-glucofuranose, phenol, 1-naphthol, and 2,6-di(tert-butyl)-4-methylphenol, and potassium carboxylate derived from pivalic acid. The living polymer of 1 was not stable at −78 °C after 5 min or longer times, but very stable at −95 °C even for 30 min. The chain-end anion could be stabilized by end-capping with tert-butyl methacrylate and 1,1-diphenylethylene, and the resulting anions remained unchanged at −78 °C even after several hours.

The anionic polymerizations of novel methoxy-substituted divinylbenzenes possessing nonequivalent vinyl groups, such as 2-methoxy-1,4-divinylbenzene (1), 4-methoxy-1,2-divinylbenzene (2), and 4-methoxy-1,3-divinylbenzene (3), are carried out with oligo(α-methylstyryl) lithium (αMSLi) in the presence of potassium tert-butoxide (tBuOK) in tetrahydrofuran at −78 °C. The poly(1)-poly(3) obtained with αMSLi/tBuOK are completely soluble and possess predicted molecular weights and narrow molecular weight distributions (MWD) (M w /M n < 1.1). On the other hand, the corresponding symmetrical divinylbenzenes, 2-methoxy-1,3-divinylbenzene (4) and 5-methoxy-1,3-divinylbenzene (5), undergo anionic polymerization to afford polymers with broad MWDs, indicating the occurrence of a serious intermolecular side reaction. The stability of the propagating carbanion derived from 1-3 is demonstrated by the quantitative efficiency of the sequential copolymerization with tert-butyl methacrylate. The chemical structure of the repeating unit of poly (1)-poly(3) is characterized by the 1 H and 13 C nuclear magnetic resonance measurements, suggesting that the polymerization of asymmetrical divinylbenzenes, 1-3, proceeds mainly on one of the nonequivalent vinyl groups. The electronic and steric effects of the electrondonating methoxy group play important roles in realizing the living anionic polymerization of these divinylbenzenes. The resulting poly(1)-poly(3) show a thermal cross-linking property over 300 °C, indicating the reactivity of the residual pendant vinyl group in each repeating unit.