纳米复合材料中界面动态特性的扫描静电显微技术研究

An Electrostatic Force Microscopy Investigation of the Dynamic Properties of Microscopic Interface in Nanocomposites

纳米复合材料中的微观界面结构和界面作用对材料的宏观介电性能,如介电常数、介电损耗、击穿强度等有十分重要的影响.本文发展了一种基于扫描静电显微探针技术的测量方法,可以直接表征二氧化钛/环氧树脂纳米复合材料的微观界面结构及相应的动态介电响应行为.实验中利用扫描探针的纳米尺度分辨能力,探测到不同温度下环氧树脂纳米复合材料的局域动态介电响应变化过程,从而获得纳米颗粒与高分子界面相互作用及极化相关的温度特性.进一步通过对二氧化钛纳米颗粒进行表面修饰,得到了两种不同特性的二氧化钛/环氧树脂界面,验证了不同界面作用引起的复合材料界面区域与非界面区域高分子链介电损耗图像的反差.

The microscopic structure and properties of the interfacial regions in nanocomposites considerably affect the dielectric properties such as dielectric constant, dielectric loss, and breakdown strength. In this paper, we developed a method based on electrostatic force microscopy （EFM） to characterize the structures and the dynamic dielectric responses of the interfaces in TiOJepoxy nanocomposites. The nanometer-scale resolution of EFM enabled direct detection of the temperature- dependent dielectric response associated with the molecular dipoles of the epoxy chains at the interface between TiO2 nanoparticles and epoxy matrix. In addition, different interfacial effects were obtained by the surface modification of TiO2 nanoparticles. The EFM images showed that the investigated interfacial regions around the two types of TiO2 nanoparticles exhibited different dielectric loss responses.