Preparation and properties of shape-stabilized phase change material cellulose benzoate-g-polyoxyethylene (2) hexadecyl ether with potential for thermal energy storage

Abstract

It is a worldwide challenge to efficiently use renewable resources to solve the current energy shortage. The existing cellulose-based material is incapable of proper power storage. In this study, a series of cellulose benzoate-g-polyoxyethylene (2) hexadecyl ether (CB-g-E₂C₁₆) solid–solid phase change materials were synthesized with cellulose as the skeleton and polyoxyethylene (2) hexadecyl ether (E₂C₁₆) as a functional side chain. The skeleton cellulose and benzoyl chloride restrict the free movement of the molecular chains of E₂C₁₆ above the phase transition temperature, leading to a solid–solid phase change. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were performed to investigate the chemical structures. The thermal energy-storage properties, thermal reliability and thermal stability of the CB-g-E₂C₁₆ were investigated by differential scanning calorimetry and thermogravimetry (TG) methods. The analysis results indicated that the E₂C₁₆ chains were successfully grafted onto the cellulose benzoate (CB) backbone and the copolymers exhibited typical solid–solid phase transition behavior. The enthalpy and degree of substitution of graft copolymers CB-g-E₂C₁₆ could be adjusted by changing the feeding ratio of the raw materials, reaction temperature and post-processing methods of CB. TG analysis results showed that the CB-g-E₂C₁₆ copolymers possessed good thermostability and they keep their stability up to 278℃. Compared with pure cellulose, CB-g-E₂C₁₆ copolymers could be dissolved in dimethyl sulfoxide and most of them could be dissolved in N,N-dimethylformamide.