Thermochromic polymer blends

Smart windows using thermochromic materials provide an excellent thermal management system over broad temperature ranges, leading to significant energy savings. Existing thermochromic materials face challenges, including difficulty in application, degradation during use, and limited durability. Here, we report a simple salted polymer blend system, consisting of poly(dimethylsiloxane), poly(ethylene oxide), and lithium perchlorate, that shows excellent thermochromic properties across an accessible temperature window and remarkable durability. The reversible temperature dependence of optical transmittance of the films arises due to the miscibility of the constituent polymers at room temperature, leading to high transparency, and the gradual phase separation and opaqueness with temperature rise. The easy-to-fabricate, stable polymer system can be a viable and cost-effective alternative to inorganic thermochromic materials such as vanadium dioxide for many applications.