Synthesis of poly(vinyl acetate)-b-poly(4-vinylpyridine) block copolymers by a combination of cobalt-mediated radical polymerization and RAFT polymerization and their use in dispersion polymerization under UV radiation

Abstract

Well-defined poly(vinyl acetate)-block-poly(4-vinylpyridine) (PVAc-b-P4VP) block copolymers were synthesized for the first time by a combination of cobaltmediated radical polymerization (CMRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization, and were used to prepare PVAc-b-P4VP hairy polystyrene (PSt) particles. PVAc end-capped by a cobalt(II) acetylacetonate complex was first synthesized by the CMRP of vinyl acetate, after which the cobalt complex was modified into a dithiobenzoate group for the RAFT polymerization of 4-vinylpyridine. The hairy PSt particles were synthesized by the dispersion polymerization of St using the PVAc-b-P4VP as both a macro-initiator and a colloidal stabilizer under UV radiation. The average size of PSt particles synthesized with 20 wt.% of PVAc-b-P4VP (M n 0 39,500 g/mol) was 136 nm (CV019.2%). Very small Au nanoparticles were successfully immobilized on the surface of the PSt particles.

Controlled/Living Radical Polymerization in Dispersed Systems: An Update

“…This approach has been described for the synthesis of PSt particles using macroRAFT agents of PMAA, 392 P4VP, 393 or PVAc-b-P4VP. 394 PnBA, PMA, and PAN particles have also been reported using macroRAFT agents of PNAM, 395 P2-EHA, 396 and PEG-b-PAN, 397 respectively. 7.3.2.…”

“…Finally, macroRAFT (co)­polymers have also been evaluated as reactive stabilizers, the goal being to covalently anchor the macroRAFT agent onto the particle surface, via the in situ formation of an amphiphilic/diblock copolymer, without seeking the control over the radical polymerization of the core-forming polymer. This approach has been described for the synthesis of PSt particles using macroRAFT agents of PMAA, P4VP, or PVAc- b -P4VP . PnBA, PMA, and PAN particles have also been reported using macroRAFT agents of PNAM, P2-EHA, and PEG- b -PAN, respectively.…”

Direct Transformation of Living Anionic Polymerization into RAFT-Based Polymerization

“…Thus, block copolymers are synthesized from an intermediate denoted as macroinitiator or macro-chain-transfer agent (macro-CTA). For this purpose, the terminal halides of ATRP products were subject to nucleophilic attack by thiocarbonylthio salts to form macro-CTAs that could further mediate RAFT polymerizations. − End-group modification of products prepared from ATRP, NMP, and cobalt-mediated polymerization with di(thiobenzoyl) disulfide afforded similar macro-RAFT agents. − A mechanistic switch from RAFT to ROP was achieved using either a unique radical-induced hydroxylation process or insertion reaction of a single molecule of hydroxyethylene cinnamate . An inverse process that switched from ROP to RAFT was accomplished using esterification of hydroxyl terminus into thiocarbonylthio moiety .…”