Bottlebrush polymers with self-immolative side chains

Abstract

A series of bottlebrush polymers with self-immolative side chains were prepared by a grafting-onto method. Poly(3-azido-2-hydroxypropyl methacrylate) (PGA) and propargyl-capped poly(carbamates) were used as the backbone and side chains, respectively. A copper-catalyzed azide–alkyne cycloaddition reaction was used to graft the side chains onto the backbone with a high grafting density. A UV cleavable o-nitrobenzyl (ONB) linker was designed at the junction site of the backbone and side chain. Under UV irradiation, the ONB linkers cleaved to break the bottlebrush molecular architecture by detaching phenylamine terminated side chains from PGA backbones. The self-immolative disassembly of the detached side chains was then followed to generate aromatic amine small molecules. The model functional bottlebrush polymers were further constructed using acrylate substituted poly(carbamates) as side chains, whose self-immolative disassembly continuously released fluorescence signals. Moreover, the total disassembly rate of the bottlebrush polymers could be conveniently tuned by tailoring the substituent group of poly(carbamate) side chains.