Synthesis of bottlebrush polymers with v-shaped side chains

Abstract

Bottlebrush polymers with v-shaped side chains were fabricated via “grafting onto” method by a combination of reversible addition fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP)/ring opening polymerization (ROP), and copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. RAFT was used to prepare poly(glycidyl methacrylate) backbones with an azide side group on each repeating unit (PGMA-N3). ATRP/ROP was used to synthesize a diversity of v-shaped side chains with an alkynyl group in the middle of polymer chain including poly(methyl methacrylate) (v(PMMA)2), poly(tert-butyl acrylate) (v(PtBA)2), polystyrene (v(PS)2), and poly(ε-caprolactone)-block-polystyrene (v(PCL-b-PS)). CuAAC reaction was then conducted to graft the alkynyl-functionalized side chains onto azide containing backbones and produce the corresponding bottlebrush polymers with varied v-shaped side chains such as PGMA283-g-v(PtBA22)2, PGMA100-g-v(PtBA22)2, PGMA100-g-v(PtBA35)2, PGMA100-g-v(PS10)2, PGMA100-g-v(PMMA30)2, and PGMA100-g-v(PCL10-b-PS24). For all these bottlebrush polymers with varied v-shaped polymer side chains, a high side chain grafting density was obtained with a value above ca. 80% based on the “grafting onto” method developed in this study.