Incorporating Polar Oxazolidinones into Polycyclooctadiene via Frontal Ring-Opening Metathesis Polymerization

Frontal ring-opening metathesis polymerization (FROMP) is a rapid, facile method that requires little energy input by utilizing the polymerization exotherm to self-propagate. Although FROMP is efficient, its scope has been limited to highly strained monomers to provide enough energy to drive the polymerization front. Copolymerization has been a viable strategy to introduce more diverse monomers to make polar-functionalized dicyclopentadiene-based thermosets. In contrast, analagous FROMP copolymerizations to produce soluble thermoplastics containing polar repeat units have yet to be explored. Herein, we report the frontal copolymerization of cyclooctadiene (COD) with 1–5 mol % of a lower ring-strain oxazolidinone-fused cyclooctene (Oxa) to synthesize polybutadiene-based copolymers. As expected, as the Oxa loading increased, the front velocity decreased by up to 50% and maximum front temperature decreased by ~16 °C compared to pCOD homopolymer. While the degradation and glass transition temperatures were minimally affected, the polar Oxa units greatly influenced crystallization and tensile properties of the resulting materials. In particular, the ductility dramatically increased from 220% strain at break for pCOD to 1900% for copolymers with 5 mol % Oxa. This study provides an easy method to incorporate polar functionality into ubiquitous polyolefins and further demonstrates the impact of dipoles on material properties towards future applications.