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

Abstract 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°C, 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°C. 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.