Novel Flexible Phase Change Materials with Mussel-Inspired Modification of Melamine Foam for Simultaneous Light-Actuated Shape Memory and Light-to-Thermal Energy Storage Capability

Form-stable phase change materials (PCMs) are widely used for thermal management. However, the strong rigidity and the weak photoabsorption ability have hindered their practical applications. Herein, we report a flexible PCM based on paraffin wax (PW) and polydopamine-coated melamine foam (MF@PDA) for the seamlessly combined light-actuated shape memory and light-to-thermal energy storage capability. The MF@PDA foams with different PDA contents, which act as supporting scaffolds to adsorb PW, are successfully obtained by varying the immersion times and the dopamine concentrations. The low density and high porosity of MF@PDA foams allow for high weight fraction of PW to be incorporated, making the PCMs show high latent heat and encapsulation ability. Simultaneously, the elastic MF@PDA foams impart the PCMs with good shape memory property by triggering the phase transition of PW. More importantly, due to the efficient photothermal effect of PDA coating, the PCMs exhibit excellent light-actuated shape memory effect (shape recovery ratio ∼ 100%, shape recovery speed ∼ 100 s) and solar-to-thermal energy storage efficiency (80.8%). The light-actuated shape recovery rates and the solar-to-thermal transfer rates are increased with the augmented amount of PDA coating. Besides, the PCMs exhibit quite stable shape memory cyclic performance and thermal reliability. This study provides a new strategy to design flexible and light-responsive PCMs with the potential to be used in advanced solar energy storage systems.