Bottlebrush Polyolefin Sulfones as Triggerable and Degradable Pressure-Sensitive Adhesives

The molecular architecture (topology) of bottlebrush polymers, featuring densely grafted side chains along a polymeric backbone, leads to unique physical properties, enabling their use as functional materials including elastomers and pressure-sensitive adhesives (PSAs). Bottlebrush polymers can form additive-free PSAs due to their architecture, but most are crosslinked materials that include all-carbon backbones, have thermally unstable disulfide bonds, or do not reach the high molar masses needed for bottlebrush PSAs. Here, we applied the alternating free-radical copolymerization of sulfur dioxide (SO₂) and norbornene-based macromonomers in a grafting-through approach to make bottlebrush polymers with number-average molar masses exceeding 1100 kg/mol and backbone degrees of polymerization exceeding 900. These first examples of poly(olefin sulfone) bottlebrush polymers incorporated polyacrylate, polymethacrylate, polystyrene, and poly(lactic acid) side chains, all attached to a poly(norbornene-alt-SO₂) backbone. Under mild alkaline conditions, these very high molecular weight bottlebrush polymers degraded considerably within 10 min and completely within 4 h. Finally, a bottlebrush polymer synthesized using this approach behaved as a PSA with a peel strength of ∼1200 N/m, substantially higher than non-degradable PSAs in commercial tapes. In sum, this work offers a versatile approach to synthesize triggerable and degradable bottlebrush polymer adhesives enabling end-of-life disposal following their intended applications.