Highly flexible GO–polyurethane solid–solid phase change composite materials for efficient photothermal conversion and thermal energy storage†

Solid–solid phase change materials (SSPCMs) are considered one of the most promising candidates for thermal energy storage due to their efficient heat storage and discharge capabilities. However, achieving both stable enthalpy and material versatility remains a significant challenge in the development of SSPCMs. In this study, we propose a simple but effective strategy for fabricating SSPCMs with high latent heat and mechanical strength. The polymers rely on triethanolamine to facilitate cross-linking and intermolecular hydrogen bonding, creating a strong cross-linking network within the material. This approach enables the SSPCM to exhibit a high phase transition enthalpy (101.2 J g⁻¹), excellent flexibility, superior tensile strength (∼35.96 MPa), and remarkable tensile strain (∼1275.4%). Additionally, the materials demonstrate excellent shape stability, shape memory, and self-healing properties, attributed to the cross-linking network. Furthermore, we add graphene oxide to the system to enhance its potential for efficient conversion, storage and release of solar energy, and the final solar thermal storage efficiency, with the addition of 0.5% GO, can reach 92%.