The Preparation And Research Of PEG Based Copolymers Soild-soild Phase Change Materials

Polyethylene glycol(PEG) based Polymer solid-solid phase change energy storage materials (SSPCMs) has received much attention and become the hot topics in the study of phase change energy storage materials (PCMs) due to the advantages of no liquid leakage, without encapsulation. But it still has the problem of small phase change latent heat and inflexible phase transition temperature in the practical application.In this work, a series linear or comb copolymer PCMs based on PEG and its derivatives polyethylene glycol monomethyl ether (MPEG) which act as phase change material were successfully synthesized. IR, POM, XRD, TGA, DSC were used to study the phase morphology, crystallinity, thermo stability and phase change behavior. And the relationship between the PEG content (and/or molecular weight) and the phase change performance of PCMs were further discussed.The research results show that the linear copolymers and comb copolymers have the typical solid-solid phase change style without liquid molecules leaking during the process of phase change. This series of SSPCMs have nearly the same size of the spherulites structure of pure PEG, which have stable reversible phase transition behavior and higher decomposition temperature. The wide phase transformation temperature range (25.5～64.4℃) enables them to be used in textiles, phase change wall and so on. In addition, the phase transition enthalpy is also much higher than that of other comb copolymer SSPCMs previously reported. The phase transition enthalpy of comb copolymer CCP2000-5000is up to159.6J/g, much higher than that of some comb copolymer SSPCMs previously reported.The phase change temperature and enthalpy of these SSPCMs can be easily varied by changing the molecular weight of PEG. The phase transition temperature and enthalpy of these SSPCMs will increase with the increase of PEG molecular weights in main chain, when the molecular weight of MPEG side chain is550g/mol. If the molecular weight of side chain MPEG increases to1000g/mol, the phase change temperature and enthalpy will also have a gradual growth trend with the increase of the molecular weight of PEG in the main chain backbone. While if the molecular weight of MPEG side chain is high to5000g/mol, the phase change temperature and phase change enthalpy will not increase with the increase of the molecular weight of PEG in the main chain, because the side chain MPEG has important implications for the crystallization of comb copolymers.