Incorporation\nof Thioacetate Pendants on a Polyalkenamer\nEnables High Extensibility

This study focuses on functionalizing polycyclooctene\n(PCOE) with\nthioacetate groups using thiol–ene click chemistry. The ethylene\nthioacetate (EVSA) copolymers produced vary in thioacetate incorporation\n(4–25 mol %) via a controlled semibatch addition technique\nwith AIBN dosing. Copolymers with 4–14 mol % thioacetate are\nsemicrystalline, while those with 20–25 mol % are amorphous.\nIncreased functionalization correlates with decreased crystallinity\nand increased stretchability, with the highest functionalization (25\nmol %) showing a modulus of 0.045 MPa and 2000% elongation at break.\nThis behavior is due to the pseudoprecise functionalization of the\nthioacetate pendants and intrinsic cross-linking that occurs during\nmelt processing. Broadband dielectric spectroscopy (BDS) indicates\na low activation energy barrier (16 kJ/mol for the β process),\nsuggesting potential self-healing applications.