Preparation of flexible solid-solid phase change materials with simultaneously thermal energy storage capability, reprocessability and dual-actuated shape memory performance

Significant progress is mainly focused on the high latent heats and stability of traditional solid-solid phase change materials (SSPCMs) capable of thermal energy storage capability. However, an ultimate goal yet to be fulfilled is to fabricate flexible and mechanical robust SSPCMs with simultaneously remarkable thermal energy storage capability and other new functions. In this work, one type of novel flexible and mechanical robust SSPCMs, namely HTPCM8K, was fabricated via incorporation of key commercial raw materials into thermosetting SSPCMs. The synthetic HTPCM8K has exceptional thermal energy storage capability with the highest latent heats of 106.3 J g-1, meanwhile has remarkable reprocessability via hot press after incorporating the dynamic urea bonds into the polymeric skeleton. Surprisingly, the mechanical properties, phase change temperature, latent heats and encapsulation ratio of recycled HTPCM8K can be comparable with those of original one, demonstrating that the devised HTPCM8K not only has remarkable malleability and reprocessability, but also can maintain preeminent latent heat storage capacity and chemical stability during multiple thermal reprocessing process. Additionally, the yield stress, breaking strength and elongation at break of the recycled HTPUs elastomers can still maintain superhigh values of 13.18 MPa, 22.77 MPa and 1190.16%, which are superior to those of most SSPCMs. Especially, combining the good dynamic nature and the hydrophilicity of PEG chains, the devised HTPCM8K has dual thermal- and water-actuated shape memory performance. Importantly, it proposed the mechanism of thermal-actuated elastic and plastic shape memory behavior into one dynamic cross-linked crystalline polymer. The flexible and mechanical robust HTPCM8K is believed to have a broad application prospect in thermal energy storage systems and recyclable intelligent response materials.