Living Anionic Polymerization of 1,4-Divinylbenzene and Its Isomers

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.