Janus polyurethane composite film with highly aligned graphene fluoride and liquid metal: A versatile technique for thermal management and electromagnetic interference shielding

Flexible and multi-functional thermoconductive polymer composites have significant potential for application in advanced electronics. However, achieving a composite with necessary requirements such as flexibility, thermal conductivity, electromagnetic interference (EMI) shielding, and electrical insulation are challenging. The concept of Janus materials has provided the requirements of advanced electronics by forming a layered structure in polyurethane via sedimentation of liquid metal (LM) and graphene fluoride (GF). The fillers in the polyurethane were elongated and aligned along the draw direction using a stretching-induced filler alignment approach, which enhanced in-plane thermal conductivity and EMI shielding performance simultaneously. The Janus composite film exhibits electrical conductivity on one side and insulation on the other side, demonstrating the true nature of the Janus structure, while the film shows superior thermal conductivity (9.62 W·m−1·K−1) and EMI shielding effectiveness (55 dB) at a draw ratio of 2. These findings provide a novel approach to fabricating multifunctional composites for electronics applications.