Tailored Silyl Ether Monomers Enable Backbone-Degradable Polynorbornene-Based Linear, Bottlebrush, and Star Copolymers through ROMP

Ring-opening metathesis polymerization (ROMP) 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 via this strategy is their lack of facile degradability, which limits 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 PEG-based bottlebrush polymers, as well as to synthesise 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.