Epoxy-based silsesquioxane (EOVS) was successfully oxidized from octavinyl silsesquioxane (OVS) and then prepared the E51/BADCy/EOVS nanocomposites with epoxy resin and cyanate ester. With EOVS additions, a lower value of dielectric constant was achieved due to the increased free volume. The positron annihilation lifetime spectroscopy (PALS) demonstrated more nanocavity introduced by POSS increased the free volume of the system, and the crosslinking density calculated from DMA was combined to determine the spatial structure of molecular chains in nanocomposites. Subsequently, the internal microstructure of materials and the types of dipoles were confirmed by Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance spectroscopy (EPR), and the effect of various dipoles on the dielectric loss was fully discussed. Surprisingly, the dielectric constant and dielectric loss even decreased to 2.0 and 0.0036 (1 MHz), which suggested E51/BADCy/EOVS nanocomposites are promising candidates in the aspect of microelectronics industry.

以八乙烯基倍半硅氧烷 (OVS) 为原料成功氧化了环氧基倍半硅氧烷 (EOVS)，然后用环氧树脂和氰酸酯制备了 E51/BADCy/EOVS 纳米复合材料。添加 EOVS 后，由于自由体积增加，介电常数值较低。正电子湮没寿命谱 (PALS) 表明 POSS 引入的更多纳米腔增加了系统的自由体积，并且结合从 DMA 计算的交联密度来确定纳米复合材料中分子链的空间结构。随后，通过傅里叶变换红外光谱（FTIR）和电子顺磁共振光谱（EPR）证实了材料的内部微观结构和偶极子的类型，并充分讨论了各种偶极子对介电损耗的影响。