Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

A series of poly(polyethylene glycol n-alkyl ether vinyl ether)s (PCmEnVEs) with various lengths of alkylchains and polyethylene glycol spacers as side chain (m = 16,18; n = 1,2) were synthesized via two steps.First, monomers-ethylene glycol hexadecyl ether vinyl ether (C16E1VE), ethylene glycol octadecyl ethervinyl ether (C18E1VE), diethylene glycol hexadecyl ether vinyl ether (C16E2VE) and diethylene glycoloctadecyl ether vinyl ether (C18E2VE) were synthesized by a modified Williamson etherification. Then,four new types of phase change materials were successfully fabricated by a living cationic polymeriza-tion. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR),thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray diffrac-tion (WAXD) were employed to characterize their composition, thermal properties and crystallizationbehavior. The results show that, the side chains of PC16E1VE, PC18E1VE, PC16E2VE and PC18E2VE are in ahexagonal lattice, and the onset temperatures for melting of PC16E1VE, PC18E1VE, PC16E2VE and PC18E2VEare 39.8.C, 37.4.C, 51.0.C and 48.9.C, the onset temperatures for crystallization are 36.7.C, 35.2.C,47.4.C and 46.3.C, respectively. The enthalpy changes of PC18E1VE, PC16E2VE and PC18E2VE are higherthan 100 J/g; on the contrary, it is 96 J/g for PC16E1VE. The enthalpy decrease is no more than 11% after 10heating and cooling cycles. The 5 wt% mass loss temperatures of PC18E1VE, PC16E2VE and PC18E2VE arehigher than 300.C; on the contrary, it fs 283.C for PC16E1VE. Using a weak polarity, flexible alkyl etherchain (-OCH2CH2O-) as a spacer to link the main chain and side chain is conducive to the crystalliza-tion of the alkyl side chain. These new phase change materials can be applied in heat storage, energyconservation, and environmental protection.