Reconfigurable high-temperature thermal protection shape memory aerogel based on phthalonitrile resin with facile template method

Shape memory polymer aerogels (SMPAs) hold great promise for aerospace thermal insulation but face high-temperature limitations. This study develops a phthalonitrile-based shape memory aerogel (SMPNA) through an in-situ polymerization template method, which exhibits remarkable compression resistance and low thermal conductivity due to its isotropic microporous structures. The shape recovery at high temperatures, based on its shape memory effect, allows SMPNA to provide dynamic thermal protection induced by its thermally driven deformation. The inherent high-temperature resistance of the matrix endows SMPNA with excellent thermal dimensional stability, exhibiting almost no shrinkage at 400 °C. In addition, after thermal treatment exceeds 600 °C, SMPNA undergoes carbonization while retains its microporous structure, thereby possessing excellent microwave absorption performance. The developed SMPNA integrates low-temperature insulation, high-temperature dynamic thermal protection, and microwave absorption capabilities after carbonization, broadening its application prospects. Furthermore, by incorporating multi-walled carbon nanotubes (MWCNTs), the SMPNA composite (SMPNAc) containing 8% MWCNTs exhibits good microwave absorption characteristics that can be modulated via shape memory behavior. Additionally, the microwave absorption performance of SMPNAc remains stable across a broad temperature range up to 400 °C. This work offers new insights for the multifunctional applications of SMPAs in high-temperature environments.