Synthesis of PVA@S-BNNSs flexible fiber backbone by electrostatic spinning assisting the construction of excellent ductile epoxy thermal interface materials

With the emergence of flexible electronics technologies based on stretchable, foldable, and bendable properties, there is a growing need for new thermal interface materials (TIMs) that possess better flexibility and stretchability. Epoxy resins, as thermal management materials commonly used to improve heat transfer and heat transport, need to have high thermal conductivity as well as excellent flexibility and a degree of stretchability. In order to devise TIMs that can be employed with flexible electronic devices, here we propose a strategy to form a flexible thermal conductive network structure with the shape of a "rice plant" inside the flexible epoxy resin matrix. The polyvinyl alcohol (PVA) flexible network skeleton constructed by the electrostatic spinning technique is regarded as the branches of the rice plant, and the ultra-sonicated boron nitride nanosheets (BNNS) are assumed to be the granular rice seeds. As a result, a perfect interconnected thermal conductivity path can be constructed, and the thermal conductivity is greatly enhanced with a relatively low boron nitride loading. Additionally, the prepared EP/PVA@S-BNNSs epoxy composites can exhibit a low elastic modulus and 153 % elongation at the break, demonstrating superior electrical insulation and excellent ductility, making them suitable for a wide range of applications in flexible electronic and wearable devices.