液相剥离法制备石墨烯及在导热硅橡胶中的应

采用高速剪切机液相剥离法, 在胆酸钠的水溶液中将鳞片石墨剥离, 离心得到石墨烯分散液。AFM、TEM、Raman表征结果发现, 剥离出的石墨烯厚度小于4层, 尺寸大约在2~3 μm, 高质量缺陷少(I_D/I_G≈0.15)。将石墨烯分散液冷冻干燥后与银粉共同添加到硅橡胶中, 制备出导热硅橡胶。利用稳态热流法测试导热硅橡胶的导热系数发现, 当添加3vol%石墨烯时, 复合材料的导热系数由未添加石墨烯时的4.900 W/(m·K)提高到12.367 W/(m·K)。综上所述, 通过液相剥离法成功制备出缺陷较少的少层石墨烯, 能够与银粉协同提高导热硅橡胶的导热系数。

Graphene: Prepared by High Speed Shearing-assisted Exfoliation and Application in Thermal Conductive Silicon

Graphene dispersion was produced by centrifugation after exfoliating the graphite in aqueous solutions containing sodium cholate as a surfactant with high speed shearing machine. The exfoliated graphene (thickness≤4 layers) showing large lateral size of around 2-3 μm and high quality (I_D/I_G≈0.15) was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and Raman spectroscopy. After freeze drying, Graphene was added in the silver-silicone rubber to produce a hybrid graphene-metal thermal conductive silicone rubber, and steady-state heat flow method was applied to study the thermal conductivity of the composite. It was found that as filler loading fraction of graphene increased from 0 to 3vol%, thermal conductivity of siliver-silicone rubber dramatically improved from 4.9 W/(m·K)to 12.367 W/(m·K). This result suggests that little-defect graphene with few layers prepared by exfoliating can significantly enhance the thermal conductivity of silicone rubber by synergy effect when combined with silver powder.