Preparation and characterization of melamine/formaldehyde/polyethylene glycol crosslinking copolymers as solid–solid phase change materials

•A novel PCM of melamine/formaldehyde/polyethylene glycol (MFPEG) was fabricated.•MFPEG is a series of infusible and insoluble crosslinking copolymers.•MFPEG owns a suitable phase change temperature range and higher enthalpy.•Thermal cycling test showed MFPEG has a favorable thermal reliability.

A kind of solid–solid phase change materials (SSPCMs), melamine/formaldehyde/polyethylene glycols (MFPEG) crosslinking copolymers, was synthesized referring to the reaction mechanism and conditions of amine–aldehyde condensation reaction and aldolization. The composition and chemical structure, thermophysical and crystallographic properties of MFPEG crosslinking copolymers were investigated by Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectrometer (1H NMR), differential scanning calorimetry (DSC), thermogravimetry analysis system (TGA), wide-angle X-ray diffraction (WXRD) and polarization optical microscopy (POM). The results indicate that MFPEGs crosslinking copolymers possess excellent phase change properties and an applicable temperature range. The maximal latent heat enthalpies of heating and cooling cycle are 109.4 and 103.9 J/g, respectively. The decomposing temperature range of MFPEGs is about 340–455 °C in nitrogen atmosphere.