Effect of Linker Length and Temperature on the Thermal Conductivity of Ethylene Dynamic Networks.

Dynamic covalent networks are a class of polymers containing exchangeable bonds. The influence of the thermodynamics and kinetics of dynamic bond exchange on the thermal conductivity and mechanical properties of dynamic networks is important for understanding how they differ from thermoplastics and thermosets. In this work, a series of ethylene dynamic networks are synthesized from benzene diboronic acid and alkane diols with different precise ethylene linker lengths. The thermal conductivity of these ethylene dynamic networks at 40 °C decreases from 0.19 to 0.095 W/(m K) when the ethylene linker length increases from 4 to 12 carbons. The thermal conductivity also has a strong temperature dependence, decreasing by a factor of 3 over the temperature range from -80 °C to 100 °C. The minimum thermal conductivity model predicts these trends of the thermal conductivity with variations in ethylene linker length and temperature.