可反应性Ag@SiO2纳米粒子填充的聚合物基复合材料微观结构与介电性能研究

项目名称： 可反应性Ag@SiO2纳米粒子填充的聚合物基复合材料微观结构与介电性能研究

项目编号： No.50807038

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 于淑会

作者单位： 中国科学院深圳先进技术研究院

项目金额： 23万元

中文摘要： 本研究采用聚乙烯吡咯烷酮（PVP）、氨水调节反应溶液的浓度和pH值，实现了纳米Ag颗粒在10～100nm范围内的可控制备。在氨水的碱性介质中通过正规酸乙酯的水解反应实现对纳米Ag颗粒的包覆。并选择具有环氧基的硅烷偶联剂对Ag@SiO2的结构表面进行改性。研究了Ag@SiO2作为填充颗粒的聚合物基复合材料的介电性能。对于Ag@SiO2/PVDF体系，当Ag@SiO2含量为28vol%，材料即变为导体，在此之前，介电常数低于50。当引入纳米BaTiO3之后， 体系则不容易发生渗流效应，Ag@SiO2含量40vol％、复合材料的介电常数在100Hz时达到723，同时其介电损耗为0.82，较不含Ag@SiO2的BaTiO3/PVDF体系分别提高了24.2和4.1倍。由于SiO2壳层和BaTiO3纳米微粒的阻隔作用，使得Ag的添加量可以高于理论渗流阈值而不发生"导通"现象。利用界面极化和微电容网络等模型对复合体系的介电行为以及SiO2包覆层的影响机制进行了系统地分析。本项目的研究结果对于获得具有高介电、低损耗的纳米填充聚合物基复合电介质材料具有较为重要的参考价值。

中文关键词： 纳米银;核壳结构;Ag@SiO2; 电介质;复合材料

英文摘要： Silver nano particles with controlled particle size in the range of 10~100nm have been prepared with liquid phase chemical method. The particle size was adjusted by controlling the ratio of PVP to AgNO3 and the amount of ammonia added as complexing agent. The as-prepared Ag was treated with tetraethoxysilane (TEOS) to form an insulating SiO2 layer on the surface (Ag@SiO2),which was further modified with a coupling agent to enhance the particle dispersability and interaction with the polymer matrix.The Ag@SiO2 nanoparticles were introduced to the PVDF, epoxy, and BaTiO3/PVDF matrix respectively to prepare dielectric composoites. In a three-phase Ag@SiO2/BaTiO3/PVDF system, it has been found that the typical "conductor/polymer" percolation effect was not observed in the composite as a result of the SiO2 layer, which prevented Ag particles from contacting with each other directly and restricted the movement of electrons under external field. The high dielectric constant of 723 and a relatively low loss of 0.82 were achieved at 100 Hz with 40 vol% Ag@SiO2 and 20 vol% BaTiO3, respectively. The microcapacitor network model and "Maxwell-Wagner-Sillars" effect were employed to investigate dielectric properties of the multi-phase composites. This study provides a guidance in obtaining nano-composites with high dielectric constant and low dielectric loss, which show potential applications in the microelectronic and high-density electronic packaging fields.

英文关键词： percolation effect；nano-composite dielectrics；core-shell Ag nano-particles；reactive functional group