Particle type composite phase change materials via microemulsion impregnation for photothermal conversion and temperature regulation of surface coatings

In order to facilitate the combination of composite phase change materials (CPCMs) and fabrics, granular CPCMs were prepared, a simple vacuum impregnation method was used to adsorb n-octadecane with disc-shaped diatomite as a carrier. To improve the adsorption capacity of n-octadecane on diatomite, the average pore size of its single point was increased from 13.35 nm to 25.54 nm through acidification. The microemulsion of n-octadecane liquid with particle size of less than 200 nm was immersed into the diatomite under vacuum conditions, and after demulsification, the particle type CPCMs with a particle size of about 30 μm was prepared. The stability, thermal properties of particle type CPCM, and its thermoregulation on textile were systematically studied. The particle type CPCM with the latent heat energy of 34.69 J/g revealed no phase leakage when heated for 30 min at 50°C. The impregnation rate of acidified diatomite was increased by 51.7% compared with original diatomite. The CPCMs mixed with polyurethane was coated on the surface of cotton fabric and evaluated the thermal properties of the fabric. The fabric was allowed to absorb heat at 40°C to reach saturation. Analysis showed that the heat storage performance of the fabric was increased by 7.9%, and the temperature difference was adjusted to 2.9–3.1°C, which effectively slowed down thermoregulatory in a relatively low temperature environment. Moreover, the coated particle type CPCM did not alter the coldness of the cotton fabric.