A major issue limiting the thermal conductivity (TC) of polymer-based composites is the inevitable vacancy among thermal conductive fillers; the fabrication of continuous thermal conductivity network is significant. In this work, we successfully constructed interpenetrating carbon nanotube (CNT) @carbonized polyvinyl alcohol (αPVA) network in polyimide (PI)/boron nitride nanosheets (BNNS) membranes through co-electrostatic spinning of polyamide acid (PAA)/BNNS precursor fibers and PVA/CNT precursor fibers and subsequent high-temperature treatment. The CNT @αPVA network works as a continuous thermal conductivity network in the membrane, which could also bridge BNNS to remove the vacancies among BNNS fillers. Due to the formation of dual thermal conductive networks, the TC of PI/BNNS with 30 wt% BNNS reached an increasement of 100% with the addition of only 0.3 wt% CNT. In addition, the composites present electrical insulating properties with volume resistivity of about 10¹⁵ Ω·cm, as well as excellent flexibility, pretty good acid–alkali tolerance, and self-extinguishing. This work provides an effective way to develop continuous thermal conductive networks in polymer-based composites for scalable thermal management applications in microelectronics devices.

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