An acceleration effect that benefits from the complexation of triazole with Cu was first confirmed in two model copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions in this work: a) 1:1 molar ratio of a diazide compound and an alkynyl-terminated poly(ethylene oxide) (ay-PEO18 with average degree of polymerization DP = 18) and b) 1:1 molar ratio of a dialkyne compound and an azido-terminated N3-PEO18. It was resulted that both model reactions produced ditriazoles as major products, although the former reaction exhibited a higher yield of PEO-PEO dimers, demonstrating better CuAAC acceleration effect. Illustrated by this acceleration effect, we developed a new method to synthesize molecular brushes with polymethacrylate backbone and ultrahigh densely grafted side chains (SCs) applying accelerated CuAAC grafting-onto strategy. Polymethacrylate backbones with multi-azido dangling groups were designed and subsequently applied for grafting-onto reaction with ay-SCs (including PEO18, PEO113, poly(methyl acrylate) (PMA31) and polydimethylacrylamide (PDMA46)) to prepare an array of molecular brushes with high grafting densities. Within our investigation, all these CuAAC grafting reactions finished within 10 minutes and the grafting density was affected by the composition of SCs and the initial molar ratios of ay-SCs to azido groups. The highest grafting density was obtained (1.34 SCs per backbone carbon atom) on both longer polymethacrylate backbone and shorter backbone when applying linear SCs with thinner structure, such as ay-PEO113.

Accelerated CuAAC coupling reaction fulfilled the synthesis of ultrahigh densely grafted polymers by grafting-onto strategy

2019 Spring National Meeting

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