Flexible Skeleton-Rigid Enhancement Strategy for SiC/Polyarylate Nanocomposite Aerogels with Integrated Thermal Stability, Sound Absorption, and Electromagnetic Wave Transmission

This work outlines a flexible skeleton-rigid enhancement strategy to meet the needs for low thermal conductivity, sound absorption, noise reduction, and electromagnetic wave transmission in aerospace, electronic communications, and energy vehicles. It involves creating high-aspect-ratio thermotropic liquid crystalline polyarylate (PAR) nanofibers via melt spinning and wet ball milling to form a customizable 3D network. Rod-shaped SiC particles are then interlocked with these nanofibers through high-speed shear, resulting in a uniform preform. Directional freeze-drying and heat treatment follow, inducing molecular chain relaxation and viscous flow on the PAR surface, forming an in situ diffusion bonding layer at the SiC-PAR interface for efficient coupling and structural reinforcement. The SiC/PAR nanocomposite aerogels feature 72% porosity and an ultralow density of 0.0428 g/cm3. Increasing the SiC content from 70 to 80 wt % boosts its maximum stress by 32.3%. It offers excellent thermal stability at 250 °C, a low thermal conductivity of 0.035 W m–1 K–1, and a sound absorption coefficient of 0.34 in the 0–5500 Hz range. It also maintains strong electromagnetic wave transmission from 9 to 12 GHz. This makes it suitable for multifunctional uses in thermal insulation, sound absorption, and electromagnetic wave transmission.