Flexible and enhanced thermal conductivity of a Al2O3@polyimide hybrid film via coaxial electrospinning

A novel core-shell structure of Al2O3 nanoparticles (NPs) attached on poly(amic acid) (PAA) fiber has been successfully developed by facile coaxial electrospinning technology for the first time. The as-prepared PAA fiber went through imidization to prepare the Al2O3@polyimide (Al2O3@PI) film. The resultant films with different Al2O3 contents are characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and dynamical mechanical analysis. The results indicated that the Al2O3 NPs could uniformly decorate the surface of fibers with a diameter of about 1 mu m, which enhanced the thermal and mechanical properties of the fiber-based films. In particular, the flexible film with a high content of Al2O3 of 59.3 wt% presents a high storage modulus (2.11 GPa) and excellent thermal stability (474 degrees C at 5% mass loss) as well as superior in plane thermal conductivity of 9.66 W m(-1) K-1. Finally, compared with pure PI film, the Al2O3@PI fiber-based film exhibits excellent thermal transfer ability in light emitting diode packaging. Therefore, the novel Al2O3@PI fiber-based film with integrated properties of insulation, thermal conductivity and flexibility can be used for wearable electronics and power devices.