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

Abstract

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 conventional 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 (ΔHm). The ΔHm 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.