Incorporation of indolinospirooxazine on ethylene-vinyl acetate copolymer to produce a intelligently temperature-regulated nonwhite cool material

Cool materials that adjust cooling efficiency according to sunlight intensity are needed because people have different needs for cooling at different times. Several colors of commercial microencapsulated photochromic powder were melt blended with ethylene-vinyl acetate copolymer in a two-roll mill at 90 °C to prepare the photochromic films of corresponding colors. Pink photochromic films [the organic photochromic compound is indolinospirooxazine (NISO)] were selected to continue the following variable experiment due to its best performance in the indoor cooling test. The pink photochromic films change color as well as transmittance according to the intensity of sunlight, thereby achieving an intelligent cooling effect. A maximum decrease around 10 °C was observed in natural environment when the addition amount of pink photochromic powder reaches 2.0 phr under strong sunlight and all films did not show cooling effect under weak sunlight. This material can be covered on buildings to regulate the indoor temperature.