Impregnation assisted graphene oxide/polyimide nanofiber composites with improved thermal conductivity and breakdown strength

As the development of integrated and flexible devices, polymer-based composites with simultaneously improved thermal conductivity, breakdown strength and mechanical properties have become urgent demands. In this study, tetrabutylammonium bromide modified graphene oxide (TGO) is utilized to fabricate the electrospun TGO/polyimide fiber membranes (E-TGO/PI), and then impregnated in polyamic acid (PAA) glue and performed thermal imidization to obtain the impregnated TGO/PI composite films (I-TGO/PI). The thermal conductivity almost linearly increases with the increasing of TGO content, and the 1wt%I-TGO/PI composite materials achieve a thermal conductivity of 0.499 W/mK and a breakdown strength of 124 kV/mm, with 16% and 311% enhancement compared to the corresponding 1wt%E-TGO/PI without impregnation. Meanwhile, the tensile strength and elongation at break of 1wt%I-TGO/PI increase by over 4 times than the pristine E-PI. Besides, the dielectric permittivity and dielectric loss of I-TGO/PI composite materials maintain at relatively low value throughout. The present work demonstrates that the combination of electrospinning and impregnation is an efficient strategy to improve the comprehensive properties of polymer composites for thermal management applications.