We have developed a facile synthetic strategy for bottlebrush polymers using coupling reactions between nitroxide and carbon-centered radicals. Specifically, backbones containing nitroxide radicals and polymer side chains are both synthesized through atom transfer radical polymerization (ATRP) using commercially available materials. After abstraction of halogen atoms, side chains with carbon-centered radical are then directly captured by nitroxide radicals on the backbones to afford bottlebrush polymers. During the whole process, no complex synthesis of small-molecule linkers is involved. Owing to the effectiveness of reaction between radicals, densely grafted bottlebrush polymers with high molecular weight (apparent Mn on the order of 106 g/mol) can be achieved. With the versatility of ATRP, the monomer structure, grafting density, side chain/backbone length can be readily controlled through employing different reaction conditions. Additionally, polymer bottlebrushes produced by this strategy can be thermo-responsive at elevated temperature (&gt; 120 °C), since the alkoxyamine bonds generated by radical coupling between nitroxide and carbon-centered radicals are thermally reversible. Overall, this synthetic strategy provides a particularly simple and efficient routine for the production of a wide variety of functional bottlebrush polymers. Comparisons will also be made regarding the properties of bottlebrush polymers synthesized by this strategy relative to those of linear polymers recovered from the elevated temperature, thermally reversible reaction.

Thermo-responsive bottlebrush polymers by a novel grafting-onto strategy based on radical coupling and atom transfer radical polymerization

256th National Meeting (2018)

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