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 degrees C for 0.5 h with oligo(a-methylstyryl)lithium, -dilithium, and -dipotassium. Poly(2)s possessing predicted molecular weights and narrow molecular weight distributions ((M) over bar(w)/(M) over bar M(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 degrees C. This deactivation reaction could be almost completely suppressed at -95 degrees C. The deprotection of poly(2) was performed by treating with Bu(4)NF in THF at 0 degrees 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.