Self-emulsifying polyethylene glycol-based nanocapsule phase change material with enhanced thermal conductivity

The preparation of micro- and nanocapsule phase change materials (NPCMs) always requires the help of emulsifiers, leading to additional cost, time and energy consumption. In this study, we prepared a polyethylene glycol (PEG)-based NPCM without using emulsifiers, showing a sustainable development of engineering. The amphiphilic prepolymer of the NPCM could self-emulsify in water forming nano micelles, which were subsequently chemically cross-linked by trimethylolpropane obtaining the NPCM. The chemical crosslinking structure endows the NPCM with a solid state even at 90 °C, addressing the leakage issue of PEG. Due to the introduction of hydroxyl-functionalized multi-walled carbon nanotubes (OH-MWCNTs), the NPCM has an enhanced thermal conductivity of 1.04 W m−1 K−1, which is much greater than those of PEG and the NPCM without the OH-MWCNTs. The latent heat values of the NPCM in the heating and cooling processes are 74.4 and 72.3 J g−1, respectively, manifesting good thermal energy storage capability. Additionally, the NPCM also has good thermal stability and thermal reliability. •We prepared a polyethylene glycol (PEG)-based NPCM without using emulsifiers.•The chemical crosslinking structure endows the NPCM with a solid state even at 90 °C, addressing the leakage issue of PEG.•The NPCM has an enhanced thermal conductivity of 1.04 W m−1 K−1, which is much greater than that of PEG.