Highly Thermoconductive, Thermostable, and Super‐Flexible Film by Engineering 1D Rigid Rod‐Like Aramid Nanofiber/2D Boron Nitride Nanosheets

Polymer‐based thermal management materials have many irreplaceable advantages not found in metals or ceramics, such as easy processing, low density, and excellent flexibility. However, their limited thermal conductivity and unsatisfactory resistance to elevated temperatures (100 MPa, 450 °C) enable effective thermal management for microelectrodes operating at temperatures beyond 200 °C. A highly thermoconductive, high‐temperature stable, and superflexible paper is fabricated via a rational construction of 1D rigid rod‐like aramid nanofibers and 2D boron nitride nanosheets (BNNS). Significantly, the rod‐like nanofiber morphology and rigid molecular chain can enable more efficient phonon transport through the 1D/2D configuration. Hence, the heat sink paper paves the way for thermal management of new and powerful components.