PROTECTION AND POLYMERIZATION OF FUNCTIONAL MONOMERS .18. SYNTHESES OF WELL-DEFINED POLY(VINYLPHENOL), POLY[(VINYLPHENYL)METHANOL], AND POLY[2-(VINYLPHENYL)ETHANOL] BY MEANS OF ANIONIC LIVING POLYMERIZATION OF STYRENE DERIVATIVES CONTAINING TERT-BUTYLDIMETHYLSILYL ETHERS

Anionic polymerization behaviors of nine styrene derivatives with hydroxy functions protected with tert-butyldimethylsilyl groups, e.g., tert-butyldimethylsilyl ethers of 4-vinylphenol (1a), (4-vinylphenyl)-methanol (2a), 2-(4-vinylphenyl)ethanol (3a), and their meta (1b-3b) and ortho isomers (1c-3c), have been examined with various anionic initiators in THF at -78-degrees-C. Among them, 1a,b, 2b, and 3a-c undergo anionic polymerization without chain-transfer and termination reactions to afford stable living polymers. The resulting polymers all are found to possess molecular weights predictable from [monomer] to [initiator] ratios and narrow molecular weight distributions, the values of M(w)BAR/M(n)BAR being around 1.1. Deprotection of the silyl groups from these polymers provides well-defined linear polystyrenes with either phenolic or alcoholic hydroxy groups. As expected, they are shown to retain desirable characteristics of their parent living polymers, e.g., controllable molecular weights and narrow molecular weight distributions. By contrast, attempts to polymerize the structurally analogous 1c, 2a, and 2c have failed. No appreciable polymerization occurs with these monomers under the identical conditions used in the successful polymerizations. The mechanisms for side reactions in the unsuccessful polymerizations are proposed.