Preparation and properties of polymeric solid-solid phase change materials of polyethylene glycol (PEG)/poly(vinyl alcohol) (PVA) copolymers by graft copolymerization

New serials of PVA-g-PEG graft copolymers with different molecular weights and different graft ratios were prepared. In these new materials,the rigid polymer PVA served as a skeleton, and the flexible polymer PEG served as a functional branch chain. The structures of the copolymers were measured with FTIR. Their phase change properties and crystallization behavior were analyzed by DSC, POM, and WAXD. During the transition, the whole polymers remained in the solid state, they all had solid-solid phase transition properties, and the phase transitions were all reversible. Compared with pure PEG, the maximum crystalline temperatures and enthalpies of the graft copolymers declined because of the addition of PVA and the value of phase change temperatures and enthalpies had no relationship with their graft ratio. The crystalline degrees of these phase change materials were affected due to the intermolecular interaction and chemical bond.