Protection and polymerization of functional monomers, 26. Synthesis of well‐defined poly[4‐(3′‐butynyl)styrene] by means of anionic polymerization of 4‐(4′‐trimethylsilyl‐3′‐butynyl)styrene

Anionic polymerization of 4‐(4′‐trimethylsilyl‐3′‐butynyl)styrene ( 2 ) was carried out in THF at −78°C for 0.5 h with oligo(α‐methylstyryl)lithium, ‐dilithium, and ‐dipotassium. Poly( 2 )s possessing predicted molecular weights and narrow molecular weight distributions ( M̄ w / M̄ n < 1.11) were quantitatively obtained in all cases. By sequential anionic copolymerization of 2 and styrene, novel block copolymers, polystyrene‐ block ‐poly( 2 ) starting either from living polystyrene or living poly( 2 ), were synthesized. After completion of the polymerization, there occurred some gradual deactivation of the propagating carbanion of poly( 2 ) at −78°C. This deactivation reaction could be almost completely suppressed at −95°C. The deprotection of poly( 2 ) was performed by treating with Bu 4 NF in THF at 0°C for 1 h. The trimethylsilyl protecting group of poly( 2 ) was completely removed to afford a poly[4‐(3′‐butynyl)styrene] of a controlled molecular structure.