Polymeric phase change material networks based on multi-telechelic polyethylene glycol-derived multimer structures for thermal energy storage

Multi-telechelic polyethylene glycol (PEG)-based multimers with multiple reactive groups at both ends of the molecular chains can be used to prepare solid-solid phase change materials (PCMs) networks with enhanced mechanical strength, shape stability, PEG weight and adjustability in crosslink density, denoted as multi-telechelic effect in this report. Herein, multi-telechelic PEG-based PCMs networks were synthesized via the crosslinking reactions between designed hydroxyl-terminated multi-telechelic PEG-based multimers and curing agents, whose parameters can be readily tuned by the structure of multi-telechelic PEG-based multimers, for example, the number of PEG-derived structural units and the functionality of curing agents. Compared to con-ventional di-telechelic diethanolamine (DEA)-cured PCMs (DPCMs), the multi-telechelic tri-hexamethylene diisocyanate-cured PCMs (TPCMs) increase to 8-50 times in the storage modulus while decreasing only by 9.4 % in melting latent heat (Delta Hm). The Delta Hm of TPCMs increases by 58.2 % from 77.0 J/g to 121.8 J/g with increasing the number of PEG-derived structural units (y) from 1 to 4 when PEG with a number-average molecular weight of 4 kDa was used. TPCMs possess fine shape and thermal stability as well as thermal reliability while the reprocessability of PCMs is endowed by introducing a transcarbamoylation catalyst. The multi-telechelic PEG -based multimers can provide an alternative approach towards high-performance PCMs networks.