Core–Shell Engineering of Conductive Fillers toward Enhanced Dielectric Properties: A Universal Polarization Mechanism in Polymer Conductor Composites. Issue 2 (18th November 2022)

• Record Type: Journal Article
• Authors: Zhou, Wenying; Cao, Guozheng; Yuan, Mengxue; Zhong, Shaolong; Wang, Yandong; Liu, Xiangrong; Cao, Dan; Peng, Weiwei; Liu, Jing; Wang, Guangheng; Dang, Zhi‐Min; Li, Bo
• Is Part Of: Advanced materials. Volume 35:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-18
• Subjects: core–shell design -- electron displacement -- filler‐clusters -- percolation -- polarization mechanisms; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202207829
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Flexible dielectric and electronic materials with high dielectric constant ( k ) and low loss are constantly pursued. Encapsulation of conductive fillers with insulating shells represents a promising approach, and has attracted substantial research efforts. However, progress is greatly impeded due to the lack of a fundamental understanding of the polarization mechanism. In this work, a series of core–shell polymer composites is studied, and the correlation between macroscopic dielectric properties (across entire composites) and microscopic polarization (around single fillers) is investigated. It is revealed that the polarization in polymer conductor composites is determined by electron transport across multiple neighboring conductive fillers—a domain‐type polarization. The formation of a core–shell filler structure affects the dielectric properties of tpolymer composites by essentially modifying the filler‐cluster size. Based on this understanding, a novel percolative composite is prepared with higher‐than‐normal filler concentration and optimized shell's electrical resistivity. The developed composite shows both high‐ k due to enlarged cluster size and low loss due to restrained charge transport simultaneously, which cannot be achieved in traditional percolative composites or via simple core–shell filler design. The revealed polarization mechanism and the optimization strategy for core–shell fillers provide critical guidance and a new paradigm, for developing advanced polymer dielectrics with promising property sets. Abstract : A new polarization mechanism based on electron displacement across a filler‐cluster is developed, which can quantitatively explain dielectric behaviors of percolative polymer composites. With the guidance, a novel design principle, via the manipulation of filler structure and composite morphology, to achieve desirable dielectric properties is demonstrated. The composite design is fundamentally different from traditional approaches based on filler–polymer interfaces.