High-damping ultralow-gel nonpolar elastomeric polymer through thiol-ene photo-click chemistry reaction

With the increasing demand for high-performance damping rubber material in various fields, improving the damping performance of existing nonpolar rubber has garnered tremendous scientific and industrial interest. However, it remains a long-standing challenge to improve the damping properties of nonpolar rubber materials due to their low intrinsic glass transition temperature (T-g) and incompatible surface energy with high-damping polar polymers or fillers. To solve this conundrum, ultra-low gel multifunctional carboxy-functional high vinyl polybutadiene HVBR (HVBR/COOH-x%) was prepared by grafting 3-mercaptopropionic acid (3PMA) onto HVBR via thiol-ene photo-click. The effects of reaction parameters including molecular weight, 1,2-vinyl content, photoinitiators, reaction time, thiol and photoinitiator dosage on gel content and carboxyl grafting ratio were investigated. The HVBR/COOH-x% demonstrate a controllable grafting ratio range from 2% to 73%. Furthermore, the increased T-g and intermolecular force resulted in excellent performance, including high-glass transition temperature of 26.3?, tensile strength of 15.52 MPa, and elongation at break of 396.16%. Particularly with a wide range of effective damping temperatures above 46.6?. Meanwhile, COOH endowed the HVBR with better self-viscosity, but also equipped it with stronger mutual viscosity. Therefore, this experiment proposes a feasible path to high damping and high adhesion in nonpolar rubber materials.