Flexible, Reprocessable, Thermal Conductive Reversibly Cross-linked Polythiourethane Composites with Hybrid Fillers and Segregated Structure

With the development of miniaturization and integration of electronic devices, heat dissipation has become one of the key issues in the electronic industry. Polymer composites with segregated structure have high thermal conductivity at low content of fillers. However, the weak interactions between matrix and fillers may destroy the mechanical property. In this work, the reversibly cross-linked polythiourethane microspheres (PTUM) are prepared; boron nitride (BN) and carbon nanotubes (CNTs) are respectively treated with different silane coupling agents to enhance the interaction with PTUM. Then, a special mixing method (heated at 60°C for 10 min and then mechanically mixed for another 20 min) is applied to further make hybrid fillers adhering tightly to the surface of PTUM. The composites show excellent thermal conductivity (0.96 W·m −1 ·K −1 ) and mechanical properties (elongation at break of 696%, tensile strength of 7.3 MPa, and toughness of 24.1 MJ/m 3 ) due to the modified hybrid fillers and segregated structure. Moreover, the composites can be effectively reprocessed due to dynamic bonds exchange. This work supplies a new method for preparing reversibly cross-linked composites with a combination of high thermal conductivity and mechanical property, showing broad applications in flexible electronic devices.