A UV-Cleavable Bottlebrush Polymer with o-Nitrobenzyl-Linked Side Chains

Abstract

An ultraviolet (UV)-cleavable bottlebrush polymer is synthesized using the "grafting-onto" strategy by combining living radical polymerization and copper-catalyzed azide-alkyne cycloaddition (CuAAC). In this approach, reversible addition-fragmentation chain transfer polymerization is used to prepare a poly(methylacrylate) backbone with azide side groups, while atom transfer radical polymerization is employed to prepare polystyrene (PS) side chains end-functionalized with o-nitrobenzyl (UV-cleavable) propargyl groups. CuAAC is then used to graft PS side chains onto the polymer backbone, producing the corresponding bottlebrush polymers with UV-cleavable PS side chains. The formation of the bottlebrush polymer is characterized by ¹ H nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), and Fourier transform infrared spectroscopy. The cleavage behavior of the bottlebrush polymer is monitored in tetrahydrofuran solution under UV irradiation by GPC and viscosity measurements.

Keywords: UV-cleavage; bottlebrush polymer; copper-catalyzed azide-alkyne cycloaddition; living polymerization technique; o-nitrobenzyl derivative.