Eco-friendly reversible photochromic epoxy resin microcapsules with strong acid and alkali resistance for energy storage via facile in-situ microencapsulation

Multi-functional microcapsule considered as a promising technique is attracting more and more attention with social development. This study successfully prepared four kinds of eco-friendly epoxy resin microcapsules both with reversible photochromic and energy storage properties via in-situ polymerization. For the microcapsules, methyl palmitate (MP), which dissolves photochromic dyes (spiropyran), was used as the core material, and four epoxy resins (EP) with various molecular structured were selected as the shell material. The properties such as thermal stability, energy storage, surface morphology and UV absorption technology of these designed microcapsules were systematically investigated by thermogravimetric (TGA), differential scanning calorimetry (DSC), scanning electron microscope (FE-SEM), and UV–vis spectrophotometer, etc. Allowing the selection of microcapsules with mentioned properties for specific environments. The results show that hydrogenated bisphenol A epoxy resin (CYDH-3000) microcapsules possessed lower activation energy and higher UV absorption. The thermal stability of bisphenol A epoxy resin (E51) microcapsules was as high as 328.4 °C. While Bisphenol F epoxy resin (NP170) microcapsules have the highest energy storage efficiency (E = 91.45 %). The lower subcooling degree of hain epoxy resin (MHR-050) microcapsules reached 20.3 °C, showing promising application prospects in the thermo-regulated field. Meanwhile, these four epoxy resin microcapsules can retain specific shapes and photochromic phenomena with little enthalpy change in 10 % H2SO4 and 10 % NaOH environments due to the corrosion resistance of epoxy resins, which establishing the technical foundation for its application in viscose spinning.