▎ 摘　　要

NOVELTY - A composite material comprises polyethylene glycol in a loose and porous foam shape, and graphene which is sparsely filled in foam pores or attached to foam wall. The thermal conductivity of the composite material is relatively low at 25 degrees C. After the ambient temperature increases to more than 60 degrees C, the polyethylene glycol shrinks into a dense block state, while the compressed graphene phases are stacked and connected to form a heat-conducting network, and the thermal conductivity of the composite material is increased. Preparation of the composite material involves uniformly dispersing (i) hydroxy-terminated polyethylene glycol in a solvent, adding acryloyl chloride, performing pre-reaction, adding an acid binding agent, and reacting to obtain polyethylene glycol acrylate, and uniformly dispersing (ii) polyethylene glycol acrylate in a partially-reduced graphene oxide aqueous dispersion, adding an initiator, reacting, curing, demolding, freeze-drying, and removing the ice phase. USE - Polyethylene glycol-graphene composite material is used in intelligent thermal management material (claimed) for thermal management requirements of lightweight and miniaturized systems. ADVANTAGE - The polyethylene glycol-graphene composite material has desired thermal conductivity, thermal insulation performance and shape memory characteristics through end-group crosslinking and freeze-drying processing. When the ambient temperature exceeds 60 degrees C, the thermal conductivity of the composite material can be increased from 0.04 W/(mK) to 0.61 W/(mK). The transformation of thermal conductivity makes the composite material to have desired temperature-response intelligent thermal management characteristics, which is appropriate for thermal management requirements of lightweight and miniaturized systems. DETAILED DESCRIPTION - A polyethylene glycol-graphene composite material comprises polyethylene glycol in a loose and porous foam shape, and graphene which is sparsely filled in foam pores or attached to foam wall. The thermal conductivity of the composite material is relatively low at 25 degrees C. After the ambient temperature increases to more than 60 degrees C, the polyethylene glycol shrinks into a dense block state, while the compressed graphene phases are stacked and connected to form a heat-conducting network, and the thermal conductivity of the composite material is increased. Preparation of the polyethylene glycol-graphene composite material involves uniformly dispersing (i) hydroxy-terminated polyethylene glycol in a solvent, adding acryloyl chloride under an inert protective gas, performing pre-reaction at room temperature, preferably 20-25 degrees C, adding an acid binding agent, increasing the temperature to 55-70 degrees C, and continuously reacting to obtain polyethylene glycol acrylate, and uniformly dispersing (ii) polyethylene glycol acrylate in a partially-reduced graphene oxide aqueous dispersion, adding an initiator, increasing the temperature to above the initiation temperature, reacting, curing, demolding to obtain a polyethylene glycol-graphene composite hydrogel, freeze-drying, and removing the ice phase. The molar ratio of acryloyl chloride with respect to hydroxyl group in polyethylene glycol is (1-5):1. The molar ratio of acid binding agent with respect to hydroxyl group in polyethylene glycol is (1-3):1. The concentration of partially-reduced graphene oxide in the partially-reduced graphene oxide aqueous dispersion is 1-5 mg/mL. The addition amount of polyethylene glycol acrylate is preferably 10-50 wt.%. An INDEPENDENT CLAIM is included for preparation of the polyethylene glycol-graphene composite material.