Han Xianghui, Chen Sheng, Lv Xuguang, Luo Hang, Zhang Dou, Bowen Chris R
Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan, 411105, Hunan Province, China.
Phys Chem Chem Phys. 2018 Jan 24;20(4):2826-2837. doi: 10.1039/c7cp07224d.
Polymer nanocomposites based on conductive fillers for high performance dielectrics have attracted increasing attention in recent years. However, a number of physical issues are unclear, such as the effect of interfacial thickness on the dielectric properties of the polymer nanocomposites, which limits the enhancement of permittivity. In this research, two core-shell structured reduced graphene oxide (rGO)@rigid-fluoro-polymer conducting fillers with different shell thicknesses are prepared using a surface-initiated reversible-addition-fragmentation chain transfer polymerization method, which are denoted as rGO@PTFMS-1 with a thin shell and rGO@PTFMS-2 with a thick shell. A rigid liquid crystalline fluoride-polymer poly{5-bis[(4-trifluoro-methoxyphenyl)oxycarbonyl]styrene} (PTFMS) is chosen for the first time to tailor the shell thicknesses of rGO via tailoring the degree of polymerization. The effect of interfacial thickness on the dielectric behavior of the P(VDF-TrFE-CTFE) nanocomposites with rGO and modified rGO is studied in detail. The results demonstrate that the percolation threshold of the nanocomposites increased from 0.68 vol% to 1.69 vol% with an increase in shell thickness. Compared to the rGO@PTFMS-1/P(VDF-TrFE-CTFE) composites, the rGO@PTFMS-2/P(VDF-TrFE-CTFE) composites exhibited a higher breakdown strength and a lower dielectric constant, which can be interpreted by interfacial polarization and the micro-capacitor model, resulting from the insulating nature of the rigid-polymer shell and the change of rGO's morphology. The findings provide an innovative approach to tailor dielectric composites, and promote a deeper understanding of the influence of interfacial region thickness on the dielectric performance.
近年来，基于导电填料的高性能聚合物纳米复合材料受到了越来越多的关注。然而，一些物理问题尚不清楚，例如界面厚度对聚合物纳米复合材料介电性能的影响，这限制了介电常数的提高。在本研究中，采用表面引发的可逆加成-断裂链转移聚合法制备了两种具有不同壳层厚度的核壳结构还原氧化石墨烯（rGO）@刚性氟聚合物导电填料，分别记为薄壳的rGO@PTFMS-1和厚壳的rGO@PTFMS-2。首次选用刚性液晶氟聚合物聚{5-双[(4-三氟甲氧基苯基)氧羰基]苯乙烯}（PTFMS），通过调节聚合度来调控rGO的壳层厚度。详细研究了界面厚度对含rGO和改性rGO的P（VDF-TrFE-CTFE）纳米复合材料介电行为的影响。结果表明，随着壳层厚度的增加，纳米复合材料的渗流阈值从0.68 vol%增加到1.69 vol%。与rGO@PTFMS-1/P（VDF-TrFE-CTFE）复合材料相比，rGO@PTFMS-2/P（VDF-TrFE-CTFE）复合材料表现出更高的击穿强度和更低的介电常数，这可以通过界面极化和微电容模型来解释，这是由刚性聚合物壳的绝缘性质和rGO形态的变化导致的。这些发现为定制介电复合材料提供了一种创新方法，并促进了对界面区域厚度对介电性能影响的更深入理解。
