Ultralow Contact Resistance of Thermal Interface Materials Enabled by the Vitrimer Chemistry of a β-Hydroxy Phosphate Ester

Highly efficient thermal interface materials (TIMs) are crucial for high-power electronic devices; however, the high thermal contact resistance (R_c) between mating surfaces limits their application. Here, we demonstrate a malleable thermoset polymer-based TIM that has a low R_cbecause of its ability to conform at the contact interface. We synthesized a β-hydroxy phosphate ester polymer (vEP, a kind of vitrimer with an associative dynamic covalent bond) and a polymer-Ag composite with conductive fillers (Ag flakes and Ag-nanoparticle-coated multiwalled carbon nanotubes). Interestingly, the total thermal resistance significantly decreased by approximately 2 orders of magnitude from 516 to 8.45 mm²K W^-1as the temperature increased from 45 to 132 °C. This was mainly due to the significantly enhanced conformability and dramatic decrease in R_cat above the topology freezing transition temperature by the exchange of the dynamic covalent bonds (vEP moiety). The proposed approach based on a vitrimer matrix (vEP) could be effective for developing TIMs that effectively minimize the interfacial thermal resistance of high-power electronic devices.