Synthesis and thermal properties of novel solid-solid phase change materials with comb-polyurethane block copolymer structure for thermal energy storage

A series of novel comb-polyurethane phase change materials (CP-PCMs) with poly(ethylene glycol) (PEG) as side chain were synthesized through the reaction between diethanolamine-modified methoxypolyethylene glycol (DMPEG) with diisocyanate and 1,4-butanediol (BDO). The structure and phase change property of CP-PCM were characterized by gel permeation chromatography (GPC), 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared (FTIR) spectroscopy, and polarization optical microscopy (POM). The 1H NMR and FTIR spectra confirmed the success synthesis of CP-PCM. The POM images showed that CP-PCM possessed a completely crystalline structure and smaller spherulites compared with the pristine methoxypolyethylene glycol (MPEG). The influence of phase change property of CP-PCMs was also investigated using differential scanning calorimetry (DSC). The results showed that the CP-PCM synthesized using isophorone diisocyanate (IPDI) or 1,6-hexamethylene diisocyanate (HDI) as diisocyanate and MPEG with molecular weight of 5000 as soft segment possessed optimal phase change property. In addition, the phase change enthalpy and temperature of CP-PCMs decreased as the weight percentage of MPEG decreased.