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

Abstract

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 μm, 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 °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.