Mechanically Strong and Thermally Insulating Polyimide Aerogels by Homogeneity Reinforcement of Aluminum Oxide Cluster

ABSTRACT High‐performance thermal insulation is critically needed in applications where heat transfer must be substantially minimized. Traditional insulating materials, whether organic or inorganic, often suffer from thermal instability or mechanical fragility. Herein, we introduce a series of lightweight, highly porous polyimide/aluminum oxide cluster (PI/AlOC) composite aerogels that exhibit superior thermal insulation properties, achieved through freeze‐drying and thermal imidization processes. The aluminum oxide clusters serve as cross‐linking agents, enhancing the interaction between polyimide molecular chains and endowing the composite with improved structural integrity and mechanical robustness, as evidenced by a compression modulus of 8.7 MPa, six‐fold greater than that of pure PI aerogels. Moreover, the high porosity, reduced pore size, and three‐dimensional network structure of the PI/AlOC composite aerogel confer exceptional thermal insulation performance, particularly at elevated temperatures, surpassing that of commercial thermal insulation materials. Thus, the PI/AlOC composite aerogels, with their high mechanical strength and outstanding thermal insulation, are promising for practical applications in thermal insulation.