Towards high performance semi-interpenetrating phase change materials networks via linear polyethylene glycol-based multimerization effect

Abstract

Semi-interpenetrating polymer network (semi-IPN)-based phase change materials (PCMs) with linear polyethylene glycol (PEG)-based multimer intends to enhance the encapsulation fraction, shape stability and mechanical strength in a synergetic way relative to semi-IPN-based PCMs with linear PEG monomer. Herein, semi-IPN-based PCMs comprised of PEG-based multimers and covalent crosslinking polyester network were successfully synthesized via efficient esterification reaction between eco-friendly citric acid and multiple aziridine ring-containing species. The linear PEG-based multimers with various PEG unit number were formed by the reaction between polyethylene glycol and toluene diisocyanate in various molar ratio. With increasing PEG unit number of linear PEG-based multimers from 1 to 6, the PEG weight fraction of PCMs increases by 48.91% (from 60 wt% to 89.35 wt%) and the storage modulus (G′) of PCMs rises (from G′ = 12390 Pa for PCM-2–0.6 at 1 Hz at 90 °C while to G′ = 12780 Pa for PCM-6–0.6 at 1 Hz at 125 °C) when PEG weight fraction is nearly 60 wt%. The maximum latent heat reaches up to 141.0 J/g with the maximum PEG weight fraction of 89.35% in PCMs with linear PEG-based multimers encapsulated. The PCMs feature shape-stable form even at 140 °C, efficient photothermal effect by introducing carbon black and degradation ability resulting from hydrolysis effect of ester structure. The enhanced comprehensive performance of semi-IPN-based PCMs is due to the introduction of linear PEG-based multimers instead of pristine PEGs, which is denoted as multimerization effect, and the semi-IPN-based PCMs with multimerization effect will broaden the application of PCMs.