液相剥离法制备石墨烯及在导热硅橡胶中的应

doi:10.15541/jim20160659

摘要/Abstract

摘要：

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。

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关键词: 液相剥离法, 石墨烯, 热导率

Abstract:

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.

Key words: liquid exfoliation, graphene, thermal conductivity

中图分类号:

TQ174

史智慧, 李莹, 闫璐, 曹韫真. 液相剥离法制备石墨烯及在导热硅橡胶中的应[J]. 无机材料学报, 2017, 32(9): 955-960.

SHI Zhi-Hui, LI Ying, YAN Lu, CAO Yun-Zhen. Graphene: Prepared by High Speed Shearing-assisted Exfoliation and Application in Thermal Conductive Silicon[J]. Journal of Inorganic Materials, 2017, 32(9): 955-960.

图/表 4

图1 (a~c)高速剪切机及其转头实物图, (d)离心得到的石墨烯分散液照片, (e~f)石墨烯的TEM照片及局部电子衍射图; (g~h)液相剥离得到的石墨烯AFM及其高度轮廓, (i~j)石墨烯片厚度和横向尺寸的分布直方图

Fig. 1 (a-c) A Silverson model L5M high-shear mixer with mixing head in 2l beaker of graphene dispersion; (d) Graphene dispersion produced by shear exfoliation; (e-f) TEM image of individual nanosheets and its electron diffraction pattern; (g-h) AFM height profiles of graphene dispersion(10 μm×10 μm); (i-j) Histogram of number of layers and lateral size of graphene flakes

图2 冷冻干燥后的石墨烯的拉曼光谱图

Fig. 2 Raman spectrum of graphene after freeze drying

图3 碘处理前(a~b)和后(c~d)片状银粉的SEM照片

Fig. 3 SEM images of the silver microflake samples before (a-b) and after (c-d) iodine modification

图4 银粉添加量与硅橡胶复合材料(a)和石墨烯添加量与银粉硅橡胶复合材料(b)导热系数关系图

Fig. 4 Thermal conductivity of the samples vs various silver filler loadings (a) and the samples vs various graphene filler loadings (b)

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