Colorless and Transparent Semialicyclic Polyimide Aerogels with Mechanical Durability for Thermal Insulation

Visible-light transparency, low thermal conductivity, and high mechanical resistance are important properties for aerogel insulators. Achieving these properties in a single aerogel, however, is a significant challenge. While aromatic polyimide aerogels are known to demonstrate high mechanical resistance, improving both visible-light transparency and thermal insulation remains a challenge. Herein, we present colorless and transparent aerogels with low thermal conductivity and high mechanical resistance based on colorless semialicyclic polyimides. The synthesis of transparent semialicyclic polyimide aerogels has been achieved through a strategic design of monomers and the establishment of a reliable sol-gel transition via a novel imidization process. These aerogels exhibit high bending strength and flexibility, as well as high thermal decomposition temperature of around 450 °C. An optimized aerogel indicates a low thermal conductivity of 27 mW m^-1 K^-1. The unprecedented characteristics of semialicyclic polyimide aerogels make them promising as advanced, transparent thermal insulators.