High-temperature thermal insulators: Constructing Al₂O₃ fibrous aerogels through scalable needleless electrospinning

Al₂O₃ nanofiber aerogels are widely used in high-temperature thermal insulation owing to their excellent thermal stability. However, the traditional sol-gel method for preparing such aerogels suffers from high brittleness. Consequently, the development of lightweight and flexible Al₂O₃ nanofiber aerogels via electrospinning technology has become a current research focus. Traditional single-needle electrospinning is limited by low nanofiber membrane productivity, which restricts the preparation efficiency and practical application of aerogels. In this study, a novel linear narrow-slit needleless spinneret was developed using needleless electrospinning technology, combined with COMSOL Multiphysics finite element simulation software. Using this spinneret, wide-width Al₂O₃/polyvinyl butyral (PVB) precursor composite nanofibers were efficiently fabricated, thereby enabling the preparation of Al₂O₃ nanofiber aerogels with outstanding thermal insulation performance. The microstructure, crystal phase, functional groups, and thermal insulation properties of Al₂O₃ nanofiber membranes prepared at different calcination temperatures were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), as well as thermal conductivity and insulation performance tests. The Al₂O₃ fibers prepared using this nozzle exhibit the lowest thermal conductivity after calcination at 700 °C, demonstrating excellent thermal insulation performance. The aerogel fabricated from these Al₂O₃ nanofibers possesses lightweight, flexible, and high-temperature-resistant characteristics: with a bulk density of only 27 mg/cm 3 and a thermal conductivity of 0.0386 W/(m·K), the aerogel maintained a surface temperature between 130 °C and 150 °C when heated on a 350 °C hot stage for 180 s. This study provides a novel approach for the efficient preparation of functional nanofiber materials, while also offering experimental references for the research and development of high-temperature thermal insulation Al₂O₃ nanofiber aerogels.