Synthesis of Well-Defined Polybenzamide-block-Polystyrene by Combination of Chain-Growth Condensation Polymerization and RAFT Polymerization.

Well-defined diblock copolymers composed of poly(N-octylbenzamide) and polystyrene were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene with a polyamide chain transfer agent (CTA) prepared via chain-growth condensation polymerization. Synthesis of a dithioester-type macro-CTA possessing the polyamide segment as an activating group was unsatisfactory due to side reactions and incomplete introduction of the benzyl dithiocarbonyl unit. On the other hand, a dithiobenzoate-CTA containing poly(N-octylbenzamide) as a radical leaving group was easily synthesized, and the RAFT polymerization of styrene with this CTA afforded poly(N-octylbenzamide)-block-polystyrene with controlled molecular weight and narrow polydispersity.

Successive chain-growth condensation polymerization for the synthesis of well-defined diblock copolymers of aromatic polyamide and aromatic polyether.

Well-defined diblock condensation copolymers composed of an aromatic polyamide and an aromatic polyether have been synthesized by means of successive chain-growth condensation polymerizations. Polymerization of a polyamide monomer with an orthogonally difunctional initiator is accompanied with side reactions. On the other hand, polymerization with a monofunctional initiator afforded well-defined polyamide, which has been converted into a macroinitiator by introduction of a terminal 4-fluorobenzophenone unit. Well-defined diblock copolymers are obtained by polymerization of a polyether monomer in the presence of this macroinitiator.