A Review of Vanadium Dioxide as an Actor of Nanothermochromism: Challenges and Perspectives for Polymer Nanocomposites

VO2 has been intensively studied as a model system for metal-insulator transition (MIT), ever since its phase switching behavior at relatively low temperature (T-c = 68 degrees C) was discovered. Its thermo-active characteristics have been studied for applications in thermal solar collectors to prevent overheating of the fluid absorber, smart windows, and smart tiles to optimize thermal comfort in buildings. In the last few decades, strong efforts were made to develop protocols to process VO2-based material into thin films, coatings, porous layers, and glazings in order to provide thermo-active properties to common substrates. A selection of complementary works in both the synthesis of VO2 nanoparticles and formulation of VO2-polymer nanocomposites is proposed in the present review. The perspective of this work is to provide an easy entry to the thermochromic nanocomposite research field as a tutorial to tackle future challenges such as improving the application-oriented properties, in particular transition temperature T-c and solar transmittance modulation Delta T-sol. Synthesis techniques to fabricate VO2 particles and nanoparticles and strategies to insert VO2 particles in a polymer matrix are presented.