A review of thermochromic materials for coating applications: production, protection, and degradation of organic thermochromic materials

With urbanization and the reduction in forest land, there has been an increase in the temperature around urban areas resulting in the urban heat effect (heat island). As a measure of the urban heat effect, the use of organic polymer thermochromic material (OPTCM) as a building material seems to be a feasible solution. OPTCM is used as a reflective coating that reflects the sunlight, reducing the electricity load on cooling system. The OPTCM easily gets degraded under sunlight and thereby limits its usage in building coating applications. To reduce the photodegradation of OPTCM, it is generally encapsulated with an inorganic metal oxide such as titanium dioxide, zinc oxide, etc. Different methods are discussed and illustrated further to achieve the necessary microencapsulation. It is necessary to study the properties of different inorganic metal oxides as the encapsulating material. The effects of these encapsulating materials on the properties of OPTCM are further discussed in this review paper.