Synthesis of bifunctional nanoencapsulated phase change materials with nano-TiO2 modified polyacrylate shell for thermal energy storage and ultraviolet absorption

A novel kind of bifunctional nanoencapsulated phase change material with thermal energy storage and ultraviolet absorption functions was successfully prepared through surfactant-free emulsion polymerization with reactive emulsifiers. These nanocapsules consisted of n-octadecane and n-butyl stearate as binary core materials and polyacrylate supplemented with titanium dioxide nanoparticles (nano-TiO2) as hybrid shell materials. The experimental results show that the monomer conversion and thermal conductivity increased and the particle size and distribution decreased with increase in nano-TiO2 content when the nano-TiO2 dosage was below 0.2 wt%. Fourier transform infrared spectroscopy and XRD confirmed that the binary phase change materials were well encapsulated inside the polyacrylate-TiO2 hybrid shell and nano-TiO2 was also successfully crosslinked in the nanocapsules. TEM demonstrated that the synthesized nanocapsules exhibited a regular spherical profile and a well-defined core–shell structure with diameter ranging from 70 to 100 nm. In addition, the results obtained from DSC, TGA and UV–visible spectrophotometry showed that the as-prepared nanocapsules had good thermal storage capacity, thermal stability and ultraviolet absorption properties. It can be considered that the resultant nanoencapsulated phase change materials with polyacrylate-TiO2 hybrid shell may have high feasibility and hold good promise in the applications of intelligent thermoregulation fabrics. © 2019 Society of Chemical Industry