Dopamine functionalization for improving crystallization behaviour of polyethylene glycol in shape-stable phase change material with silica fume as the matrix

A new shape-stable phase change material (PEG/Dop-SF) was developed by using biomimetic modification of silica fume (SF) with dopamine (Dop) as the supporting matrix (Dop-SF). Biomimetic modification with dopamine has many advantages, such as a lack of toxicity and pollution, mild conditions and easy operation, and could improve the crystallization behaviours of PEG molecules in the PEG/Dop-SF. Moreover, the DSC results shows that the phase change enthalpy of PEG/Dop-SF is higher than that of PEG/SF. When the poly-dopamine adhered to the SF , the o-dihydroxybenzene of the dopamine linked with the hydroxyl of the SF by hydrogen bonding, leading to the freeing of the imino groups of poly-dopamine; therefore, in the process of fixing PEG in Dop-SF, the free imino groups of the poly-dopamine combined with the hydroxyl of the PEG by hydrogen bonding. This mechanism is inferred to characterize the interaction between PEG and Dop-SF. According to the results of the DSC and TGA measurements, the PEG/Dop-SF exhibited favourable heat storage capacity and thermal stability properties.