Preparation and characteristics of composite films with functionalized graphene/polyimide

Abstract Polyimide (PI) has the inherent defect of poor intrinsic thermal conductivity and cannot meet the increasing demand for rapid heat dissipation in the thermal management introduction. To improve the thermal conductivity of PI, in this study, thick sheet graphene‐ionic liquid (TSG‐IL) functionalized graphene has been prepared by a one‐step ultrasonic‐chemical method. Under the action of mechanical force, IL is successfully modified on the surface of TSG, and TSG is peeled to some extent. TSG‐IL/PI has been prepared the typical method of solution casting followed by thermal imidization. The structure, morphology, thermal conductivity, and mechanical properties of the composites are evaluated by Fourier‐transform infrared spectroscopy, x‐ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and Hot Disk thermal conductivity tests. When the amount of TSG‐IL is 0.3 wt%, the thermal conductivity of TSG‐IL/PI (0.18 W·m −1 ·k −1 ) than pure PI and TSG (ultrasonication)/PI increased by 50.0% and 28.6%, respectively. Moreover, it can maintain good mechanical properties, and its tensile strength (121.5 MPa) is 6.5% and 3.5% higher than that of pure PI and TSG (ultrasonication)/PI, respectively. The potential for application in the preparation of composites with high‐thermal conductivity is promising.