Preparation and performance characterisation of a physically and chemically crosslinked self-healing phase change material

This paper addresses the leakage, low thermal conductivity, low enthalpy, structural instability and difficult recovery problems associated with traditional polyethylene glycol (PEG)-based polyurethane phase change materials (PCMs). To this end, a multi-scaffold flexible composite phase change material (DS-FCPCM) was prepared via a combination of physical adsorption and chemical bonding. Structurally, expanded graphite-silica sol was employed as the physical adsorption scaffold, diphenylmethane diisocyanate (MDI) as the hard segment of the chemical cross-linking scaffold, and butanedione dioxime (DMG) as a chain extender to achieve PEG encapsulation. The study revealed that the thermal conductivity of DS-FCPCM measured 1.81 times higher than that of pure PEG. Following 200 thermal cycles, the material exhibited consistent heat storage capacity relative to its initial state without any leakage. The incorporation of DMG facilitated the formation of oxime-urethane bonds, a class of dynamic covalent bonds, which endowed the material with fracture-healing capabilities. extending its service life while reducing maintenance costs. Furthermore, heating and cooling experiments verified the thermal regulation ability of DS-FCPCM in practical applications. The results showed that the thermal response rate of the DS-FCPCM sample was 2.11 times that of pure PEG, and the maximum temperature difference of the system at the same time was 8.1 °C. This work provides a new approach to improving the heat storage performance of polyurethane PCMs, and is of great significance for the development of reworkable and environmentally friendly energy storage materials. • High-efficiency physical heat transfer channels. • The thermal conductivity is 1.81 times that of pure PEG. • Self-healing chemical network. • Material encapsulation techniques using a hybrid physical and chemical approach. • Materials heat absorption/release test rig.