Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA.
ACS Appl Mater Interfaces. 2013 Mar 13;5(5):1636-42. doi: 10.1021/am302520e. Epub 2013 Feb 22.
SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 °C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.
SiO2 包覆的 Fe3O4 亚微米级球形粒子（具有导电核/绝缘壳结构）采用水热法制备，并以 10 和 20 体积%的负载量装入双酚 E 氰酸酯基质中，以合成多功能复合材料。所得复合材料的介电常数在宽频率和温度范围内得到增强，而由于单个导电 Fe3O4 亚微米球的绝缘 SiO2 涂层，纯净氰酸酯聚合物的低介电损耗角正切值在 160°C 时基本保持不变。这些复合材料还表现出室温下高的介电击穿强度。动态力学分析表明，填充 20 体积%填料的复合材料的储能模量是纯树脂的两倍，但玻璃化转变温度随填料含量的增加而显著降低。磁测量表明，这些复合材料具有较大的饱和磁化强度和可忽略的低矫顽力和剩余磁化强度。
