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

Abstract

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.

Novel, flexible, and transparent thin film polyimide aerogels with enhanced thermal insulation and high service temperature

“…6(B), the fabricated aerogel films in this work improved the optical transparency and reduced the shrinkage over the previously reported PI aerogels with comparable backbone chemistry. 71,75 This could be due to different processing techniques, as well as slightly different chemical compositions, such as using different chemical crosslinkers. However, the facts behind optical transparency and aerogel shrinkage are still not fully clear, and the parameters such as chain arrangement, chain packing ability, and molecular weight may also affect both optical transparency and aerogel shrinkage behaviour.…”

Transparent and Bendable Silica Aerogels Integrated with CsxWO3 Films for Photothermal Temperature Self-Regulating Systems

“…Unfortunately, conventional silica aerogels are not capable of obtaining both high transparency and bending resistance, which greatly limits the application of highly transparent silica aerogels in the field of photothermal applications. 39 In the present work, the prepared C−Si-aerogel had both high transparency and bending resistance. Furthermore, it still maintains high transparency when it is bent (Figure 1b).…”

The Aramid-Coating-on-Aramid Strategy toward Strong, Tough, and Foldable Polymer Aerogel Films

“…The section morphology of the surface of corresponding films is revealed in Figure 2a2 40 PI nanofiber aerogel film, 41 Kevlar nanofiber aerogel film, 9 BN aerogel film, 42 silica/PEG aerogel film, 43 chopped aramid fiber reinforced PPTA aerogel, 44 and PI aerogel membrane. 45 The mechanical properties of HA/PANF aerogel composite films are improved significantly in comparison with PANF aerogel films. The visual effects have been revealed by the folding and tape-stripping tests.…”

“…(g) SEM images of the failure surface at cross-section view on HA/PANF-18.4-240. (h) Specific strength and specific modulus of HA/PANF-18.4-240 in comparison with the reported aerogel films of PI aerogel,40 PI nanofiber aerogel film,41 Kevlar nanofiber aerogel film,9 BN aerogel film,42 silica/PEG aerogel film,43 chopped aramid fiber reinforced PPTA aerogel,44 and PI aerogel membrane 45.…”