Flexibility and Thermal Storage Properties of Polyurethane Adhesive Supported Phase Change Composites Based on Polyurethane Phase Change Materials

Polyurethane phase change materials (PUPCMs) have been extensively applied in smart textiles and wearable electronic devices because of their excellent energy storage capacity. To realize the flexibility of PUPCMs for certain deformation and compact contact with objects, suitable support structures have been chosen to prepare polyurethane phase change composites (PUFPCCs) with energy storage capacity and device-level flexibility. In this work, PUPCM was prepared by the prepolymer method with polyethylene glycol (PEG) as the soft segment, 4,4-dicyclohexylmethane diisocyanate (HMDI) and 1,2-hexanediol as the hard segment. And polyurethane-based adhesives (PUA) were chosen to provide a support structure for PUFPCCs by physically blending and casting with prepared PUPCM. PUFPCCs showed good flexibility attributed to the film-forming performance of polyurethane-based adhesive in the composites. The chemical structure, crystallization properties, phase transformation properties and thermal stability of the prepared PUPCM and PUFPCCs were investigated via Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectroscopy, X-ray diffraction (XRD), polarizing optical microscope (POM), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis respectively. The phase change temperature of PUFPCCs ranged from 36 to 40 ℃. The maximum enthalpy value of PUFPCCs was up to 40 J/g for daily application. Moreover, the thermal stability of PUPCM was improved attribute to the support structure of PUA in PUFPCCs. Therefore, the prepared PUFPCCs have great potential for application in flexible wearable devices due to their excellent flexibility, suitable phase transition temperature close to human body temperature, high enthalpy value and improved thermal stability.