High Latent Heat and Recyclable Phase-Change Materials for Photothermoelectric Conversion.

Realizing organic phase-change material networks with excellent recyclability while maintaining high latent heat still faces great challenges due to the difficult trade-off between network composition. Herein, the high latent heat and recyclable phase-change materials (RPCMs) were developed by integrating linear poly(ethylene glycol) (PEG) multimers as phase-change components and the dynamic covalent cross-linking polyurethane network components in a semi-interpenetrating polymer network structure. The latent heat (54.7-145.0 J/g) can be readily tuned by the weight fraction of linear PEG multimers and the molecular weight of PEGs used in RPCMs. The RPCMs have excellent recyclability/reprocessability with activation energy of 81.23-125.84 kJ/mol by introducing dynamic disulfide bonds in the cross-linking network structure components in RPCMs while enabling the adjustable mechanical stress (10.72-14.04 MPa) and strain (7.40-266.22%), high thermal reliability, and high thermal stability. Efficient photothermal RPCMs were realized by introducing polydopamine particles in the RPCM matrix. The thermal management system and the photothermoelectric generator were designed based on the advantages of high latent heat and efficient photothermal ability of RPCMs and further demonstrated the excellent thermal management ability and photothermoelectric properties.