Enhanced thermal conductivity of electrically insulating polydimethylsiloxane composites with boron nitride nanosheet and aluminum oxide for thermal management on flexible electronics

Abstract With the trend of integration and miniaturization of stretchable electronics, thermal management has been a crucial issue. Developing novel materials with high thermal conductivity (TC) and flexibility is urgent. Herein, we report a stretchable polydimethylsiloxane (PDMS)/boron nitride nanosheet (BNNS)@spherical aluminum oxide (Al 2 O 3 ) composite with high TC and electrical insulation prepared by a two‐step strategy of sucrose‐template and hot‐pressing. An effective foam‐pressing route benefits the composites to form a three‐dimensional thermally conductive networks, improving the in‐plane TC value of the resultant composite to 4.03 W/(mK) at the filler mass fraction of 35.7 wt% and enhancing to 4.66 W/(mK) under 40% stretching ratio. Meanwhile, the composites can be restored to their former state and retain thermally conductive stability with repeated bending and twisting tests. Moreover, the composites were applied in LED with stretching, exhibiting good heat dissipation performance. These results demonstrate this PDMS composite can be potentially utilized as a high‐performance material to solve thermal management problems in flexible electronics. Highlights The heat conduction network is prepared by sucrose‐template and hot‐pressing. BNNS@P‐Al 2 O 3 fillers are self‐assembled via the electrostatic interaction. The composites exhibit good thermal conduction and superior flexibility. The thermal conductivity of the composite increases after stretching. The composites can retain thermal conductive stability after deformation.