Processable and recyclable crosslinking solid-solid phase change materials based on dynamic disulfide covalent adaptable networks for thermal energy storage

Highlights: • The chemical dynamic crosslinking SSPCMs (V-PCMs) were fabricated for thermal energy storage. • V-PCMs show solid-solid phase change characteristic and can repeated store and release heat via the melting and crystallization of PEG chains. • V-PCMs can be reprocessed through hot press through the dynamic exchange reaction of disulfide. • The reprocessed V-PCMs also show excellent energy storage ability and solid-solid phase characteristic. Generally, the chemically crosslinking solid-solid phase change materials (PCMs) are fabricated to address the issues of leakage and poor mechanical properties of traditional PCMs. However, the solid-solid PCMs also bring environmental pollution and resources waste as the permanent chemically crosslinking polymers cannot be recycled and reprocessed once molded. Herein, we reported a dynamic-covalent- crosslinking PCMs (V-PCMs) consisting of polyethylene glycol (PEG) as phase change ingredient, polyaryl polymethylene isocyanate (PAPI) as crosslinking points and disulfide as dynamic bonds. The as-prepared V-PCMs can reversibly store and release heat via melting and crystallization of PEG chains, and exhibit anti-leakage performance and solid-solid phase change merit due to chemically crosslinking networks even above melting point (T_m) of PEG. Besides, the V-PCMs show recycling and reprocessing ability from association mechanism of dynamic disulfide bonds. Also, the recycled V-PCMs can reversibly store and release heat and exhibit solid-solid phase change characteristic as original V-PCMs. This method provides a promising way for the fabrication of chemically crosslinking solid-solid PCMs with recyclability and multi-functionalization.