▎ 摘　　要

In this letter, we report an "ultrasonication-free" direct exfoliation method to obtain graphene oxide with large lateral size (LGO). The average size of LGO sheets is about 50 mu m *50 mu m. The g-LGO film shows a superior in-plane thermal conductivity after the graphitization treatment. Furthermore, the in situ "molecular welding", using polyimide (PI) to weld up the GO sheets, is conducted to improve the performance of hybrid thermal conducting film. The thermal conductivity of g-LGO/PI film is 1053.975 +/- 8.762 W m(-1 )K(-1), superior to that of the g-LGO film and g-SGO/Pl. The direct preparation method to obtain GO with large lateral size, followed by such an in situ "molecular welding" strategy by PI, provides a promising way to fabricate graphene-based film for efficient thermal management. (C) 2018 Elsevier B.V. All rights reserved.