Polybenzoxazine aerogels created in Lewis acid catalysis for thermal insulation matrix in deep space exploration

Polybenzoxazine aerogel is a new polymer aerogel material developed in recent years, which the ring-opening polymerization of benzoxazine monomer under high temperature or HCl could achieve the formation of cross-linked three-dimensional network structure so that to further reduce the cost of preparation. However, HCl as a catalyst has the disadvantages of easy volatilization and corrosion. Here we introduced Lewis acid as the catalyst for fabricating nanoporous polybenzoxazine aerogels with low density and self-extinguishing properties depending upon the evolution law for the influence of the mixed ratio of Lewis acid and hydrochloric acid (volume ratio) on the corresponding aerogels. The results show that PBz aerogels prepared in the mixed acid environment (with n-hexane as the exchange solvent) have a good three-dimensional nanopore network structure, and the pore size distribution is in the range of 20–140 nm. Additionally, the obvious self-extinguishing performance (even exposing to a flame at 1200 °C), low density and excellent mechanical properties are reflected as well, potentially suggesting the broad application prospects in the field of aerospace.