The influence of hydrogen bonding on N-methyldiethanolamine-extended polyurethane solid–solid phase change materials for energy storage

Abstract

Hydrogen bonding was used to enhance the crystallinity and thus increase the phase change enthalpy of thermoplastic poly(ethylene glycol)-based polyurethane. With novel hydrogen bonding between two hard segments (NH⋯N) in N-methyldiethanolamine-extended polyurethane (NPU), the intensity of the NH⋯OC hydrogen bond between two hard segments increased, while that of the NH⋯O hydrogen bond between soft and hard segments decreased. The crystallinity and energy storage capability of NPU benefited from these and was thus enhanced. The phase change enthalpy was approximately 140 J g⁻¹, which is very close to the highest value reported for cross-linked polyurethane. In addition, the crystallinity and crystallite perfection of NPU increased with the regular arrangement of soft segments and the microphase separation between soft and hard domains. The influence of the three different hydrogen bonds on the phase change enthalpy, crystallinity, crystallization morphology and microphase structure of the soft segment was discussed.