Percolating polymeric composites present enormous potential owing to high dielectric constant () which can be realized near the percolation threshold, but the accompanied large loss forbids their extensive use in practice. Great efforts have been devoted to coat conductive particles with an insulating shell for constrained dielectric loss, yet they markedly reduce . In this work, we explore poly(vinylidene fluoride) (PVDF) composites with a serial of core@double-shell Al@AlO@PDA (polydopamine) nanoparticles with various PDA shell thicknesses. It reveals that the high of the nanocomposites results from a fast intra-particle polarization and a slow inter-particle polarization. The formation of double-shell enables the independent control of the two polarizations always coupled in traditional percolating composites. Through facilitating intra-particle polarization and repressing inter-particle polarization, Al@AlO@PDA/PVDF can achieve a much higher and lower dielectric loss simultaneously, far exceeding the unmodified Al@AlO/PVDF. Moreover, the calculated activation energy of carrier migration in Al@AlO@PDA/PVDF is obviously higher than that in untreated nanocomposites, indicating enhanced charge-trapping capability in the core@double-shell nanofiller composites. This core@double-shell strategy offers a new paradigm for the design and preparation of percolating composites with desirable dielectric performances.

中文翻译：

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通过解耦颗粒内极化和颗粒间极化改善核@双壳结构Al@Al2O3@PDA/PVDF纳米复合材料的介电性能

渗滤聚合物复合材料由于可以在渗滤阈值附近实现高介电常数而呈现出巨大的潜力，但随之而来的大损耗阻碍了它们在实践中的广泛使用。为了限制介电损耗，人们付出了巨大的努力，用绝缘壳包裹导电颗粒，但它们却显着降低了。在这项工作中，我们探索了具有一系列具有不同PDA壳厚度的核@双壳Al@Al2O@PDA（聚多巴胺）纳米颗粒的聚偏二氟乙烯（PVDF）复合材料。它揭示了纳米复合材料的高强度是由于快速的颗粒内极化和缓慢的颗粒间极化造成的。双壳层的形成使得能够独立控制传统渗滤复合材料中始终耦合的两种偏振。通过促进颗粒内极化和抑制颗粒间极化，Al@Al2O@PDA/PVDF可以同时实现更高和更低的介电损耗，远远超过未改性的Al@Al2O/PVDF。此外，计算得出的Al@Al2O@PDA/PVDF中载流子迁移活化能明显高于未处理的纳米复合材料，表明核@双壳纳米填料复合材料的电荷捕获能力增强。这种核@双壳策略为设计和制备具有理想介电性能的渗透复合材料提供了新的范例。