Correlation between stress relaxation dynamics and thermochemistry for covalent adaptive networks polymers

Smart polymers based on covalent adaptive networks (CANs) with reversible covalent bonds have drawn tremendous attention in the past few years. The relaxation properties of CANs polymers play an important role because of their stimuli-responsive capability. Here, we elucidate the correlation between the stress relaxation dynamics and reaction thermochemistry of CANs polymers. Diels-Alder (DA) reaction based cross-linked elastomers are utilized as model CANs polymers. In situ FTIR data reveals the dynamic reaction kinetics and thermodynamics in the solid state. The influence of cross-linking density on the temperature-dependent stress relaxation time of the CANs polymers well above the gel point can be normalized by the relative distance to the gel point conversion. Combining the Semenov-Rubinstein theory and Arrhenius' law, a simple scaling relationship between normalized relaxation time and reaction kinetics is established for CANs polymers.