Polyimide Aerogel Membranes with Adjustable Transparency and High Flexibility for Highly Efficient Solar Thermal Collection

Aerogel-based solar collectors inherently possess superinsulated performance, which can achieve green and sustainable thermal collection under atmospheric pressure without the need of a vacuum gap. However, the inherent brittleness, low transparency, and weak mechanical properties of aerogels limit the practical application as solar collectors. Herein, polyimide aerogel membranes (PIAMs) with integrated properties of robust flexibility, high transparency, and low thermal conductivity have been prepared. The prepared PIAMs achieve the adjustable transparency and significant transformation from fragility to high flexibility by introducing the asymmetric molecular structure. In particular, the prepared PIAMs realize an average optical transmittance of ∼90% over the long wavelength range of 500–2650 nm and exhibit high flexibility, a low density of 0.161 g/cm3, a low thermal conductivity of 0.045 W/mK, and a robust tensile strength of 6.02 MPa. Moreover, a simple and low-cost parabolic trough solar collecting device is assembled using PIAMs as an exterior structure, which could operate at atmospheric conditions and achieve highly efficient thermal collection. The results demonstrate that the effective thermal collecting temperature of solar collector was up to 231.5 °C. The as-prepared PIAMs with robust flexibility and high optical transparency can be used as the candidate for the application of solar collectors and advanced optical elements.