Tailored silyl ether monomers enable backbone-degradable polynorbornene-based linear, bottlebrush and star copolymers through ROMP

Ring-opening metathesis polymerization of norbornene-based (macro)monomers is a powerful approach for the synthesis of macromolecules with diverse compositions and complex architectures. Nevertheless, a fundamental limitation of polymers prepared by this strategy is their lack of facile degradability, limiting their utility in a range of applications. Here we describe a class of readily available bifunctional silyl ether-based cyclic olefins that copolymerize efficiently with norbornene-based (macro)monomers to provide copolymers with backbone degradability under mildly acidic aqueous conditions and degradation rates that can be tuned over several orders of magnitude, depending on the silyl ether substituents. These monomers can be used to manipulate the in vivo biodistribution and clearance rate of polyethylene glycol-based bottlebrush polymers, as well as to synthesize linear, bottlebrush and brush-arm star copolymers with degradable segments. We expect that this work will enable preparation of degradable polymers by ROMP for biomedical applications, responsive self-assembly and improved sustainability.