One-pot polymer brush synthesis via simultaneous isocyanate coupling chemistry and grafting from RAFT polymerization

One-pot 'grafting from' of polystyrene on polydopamine coated SiO2 particles was investigated using a newly developed carbonyl-azide reversible addition-fragmentation chain transfer (RAFT) agent. Simultaneously during the RAFT polymerization of styrene, the carbonyl-azide group of the CTA rearranges into an isocyanate moiety permitting the one-pot coupling to functional surfaces. The one-pot coupling to the polydopamine surfaces was investigated, separately, using both the non-catalyzed amine-isocyanate coupling and the metal catalyzed alcohol-isocyanate coupling. Thermogravimetric analysis showed that the catalyzed one-pot 'grafting from' process produced nearly double the weight increase, and thus higher grafting density, when compared to the uncatalyzed system. These results are consistent with more available hydroxyl groups on the polydopamine surface. Finally, both one-pot 'grafting from' approaches exhibited higher grafting density when compared to their analogous 'grafting to' strategies using a-isocyanate terminated polystyrene and thus superseding previous 'grafting from' processes where two-steps were normally required.