Embedding Cleavable Enol Ether Linkages Into Cyclic Polymer Backbones Through REMP

The introduction of cleavable bonds into a fully hydrocarbon polymer backbone represents a promising strategy for imparting stimuli-responsive degradability. Here, we demonstrate this concept through the synthesis of degradable cyclic polymers via ring-expansion metathesis copolymerization (REMP) between cyclic enol ether 2,3-dihydrofuran (DHF) and a series of diester- and dicarboximide-functionalized exo-(oxa)norbornene derivatives. The copolymerization behavior is governed by the reactivity of the comonomers and the use of the sterically hindered, tethered ruthenium initiator CB6. NMR analysis confirms a high degree of alternation in the resulting copolymers. Importantly, these materials undergo degradation under mild acidic conditions through hydrolysis of the enol ether moieties embedded within the backbone. This work introduces a versatile platform for the design of degradable cyclic polymers, offering promising prospects for sustainable and responsive polymer materials.