Bifunctional bimetal-POSS films integrating UV-IR shielding and reversible thermochromism

Sunlight is one of the most significant energy sources that we utilized in our daily life. Although it brings great benefits to us, due to the high energy of the ultraviolet part in sunlight, long time exposure to sunlight may cause severe problems to both humans and materials, such as skin cancer, material fatigue, and degradation. Also, the infrared part of the light can also lead to energy accumulation, heating the surface in an undesirable way. In order to ameliorate the ultraviolet shielding ability of thermochromic materials. In this paper, we synthesized a kind of novel film materials through coordinated self-assembly at room temperature in a very simple and green method. The material is mainly composed of two kinds of metal salts (Cr(NO₃)₃·9H₂O and CuSO₄·5H₂O) and octa-aminopropyl POSS, exhibiting great reversible thermochromic property from 20 to 80 ℃, superb UV shielding (100%) performance, and excellent infrared shielding (99%) ability. By increasing the ratio of CuSO₄·5H₂O, the UV shielding effectiveness was enhanced and it achieved nearly 100% along with 99% IR shielding effectiveness at 780–1400 nm when the addition is 50%. The relevant mechanisms were illustrated by decomposition analysis through UV–Vis spectroscopy, in situ XPS, in situ XRD, FT-IR, TG-MS tests, and molecular simulations. These unique properties make this material very promising in various areas, such as new generation smart windows, functional coatings, and temperature sensors.