Tough and sustainable solid-solid phase change materials achieved via reversible crosslinking for thermal management

Phase change materials (PCMs) exhibit significant potential for overcoming the issues related to thermal energy storage and management. However, they have faced persistent challenges in applications due to liquid leakage and solid rigidity. Novel tough and sustainable solid-solid phase change materials (SSPCMs) have been achieved using the designed carboxyl-epoxy group reactive system, which forms a reversible vitrimeric structure after crosslinking. It is demonstrated that the networks overcome the limitations of liquid leakage and solid rigidity, showing excellent phase stability after being heated for 5 hours with a tensile strength of 13.5 MPa and an elongation at break of 45%. The highest phase transition enthalpy of the prepared SSPCMs is 92.01 J g^-1. The reversible phase transition of polyethylene glycol (PEG) segments locked within the networks enables excellent smart shape memory features. Notably, the networks can undergo rearrangement through interesterification, thereby acquiring recyclability and self-healing properties. Additionally, the thermal conductivity of the matrix is enhanced through the addition of BN. It is further demonstrated that the thermally conductive PCMs retain high toughness, recyclability and shape memory features, while simultaneously exhibiting potential thermal management capabilities.