Relationship between segmental, chain, and bond relaxation processes in model telechelic vitrimers

Polymers with associative dynamic covalent links, vitrimers, can exhibit thermo-rheological characteristics enabling properties such as self-healing. Largely, vitrimeric properties are controlled by the bond exchange mechanism. While dependent on linkage chemistry, bond exchange is expected to interrelate with dynamical processes of glass-forming polymers, including segmental and strand relaxation. The interaction between these processes, especially as the system approaches its vitrimer arrest and glass transition temperatures (T_g), remains incompletely understood. We report results of a coarse-grained associative bond exchange model in a glass-forming polymer. We demonstrate that a classical bond-swapping algorithm yields a good minimal model of associative bond exchange, with a well-defined, tunable activation state. Our work shows a decoupling of the bond-swapping and segmental relaxation processes at high temperature, with a new regime of behavior as T_g is approached. Results provide insights into the coupling of glassy and bonded vitrimer dynamics, with implications for the rational control of vitrimer properties.