Coupling agent-functionalized boron nitride (f-BN) and glycidyl methacrylate-grafted graphene (g-TrG) are simultaneously blended with polyimide (PI) to fabricate a flexible, electrically insulating and thermally conductive PI composite film. The silk-like g-TrG successfully fills in the gap between PI and f-BN to complete the thermal conduction network. In addition, the strong interaction between surface functional groups on f-BN and g-TrG contributes to the effective phonon transfer in the PI matrix. The thermal conductivity (TC) of the PI/f-BN composite films containing additional 1 wt % of g-TrG is at least doubled to the value of PI/f-BN and as high as 16 times to that of the pure PI. The hybrid film PI/f-BN-50/g-TrG-1 exhibits excellent flexibility, sufficient insulating property, the highest TC of 2.11 W/mK, and ultralow coefficient of thermal expansion of 11 ppm/K, which are perfect conditions for future flexible substrate materials requiring efficient heat dissipation.

Like the thigmonastic responses of the leaves of Mimosa pudica, the curling of organosoluble and free‐standing polyimide (PI) films under the stimuli of fingertip‐touching or air‐blowing is discovered for the first time. The authors discover that the PI films at the dry status can rapidly and reversibly attract and release water molecules at the interface of the thin film in response to the changes of environmental humidity. The moisture‐triggered heterogeneous deformation across the film leads to self‐curling of PI films. With the blending of suitable amounts of sulfonated‐polyaniline (PANI‐S) to the PI matrix, the resultant PANI‐S/PI film can more effectively breath water from the air and simultaneously create more significant deformation and faster recovery. With the suitable designed patterns on the film, it can serve a highly sensitive and reliable actuator to grasp and release subjects as well as to fold into 3D structures, and to roll like a tank tread by providing trace moisture gradients. This robust PANI‐S/PI film can be cast into any shape or coated on various substrates and thus is a promising material for smart delivery systems in industrial applications.