Conductive polymer composites with segregated structures

Conductive polymer composites (CPCs) have generated significant academic and industrial interest for several decades. Unfortunately, ordinary CPCs with random conductive networks generally require high conductive filler loadings at the insulator/conductor transition, requiring complex processing and exhibiting inferior mechanical properties and low economic affordability. Segregated CPC (s-CPC) contains conductive fillers that are segregated in the perimeters of the polymeric granules instead of being randomly distributed throughout the bulk CPC material; these materials are overwhelmingly superior compared to normal CPCs. For example, the s-CPC materials have an ultralow percolation concentration (0.005-0.1 vol%), superior electrical conductivity (up to 106 S/m), and reasonable electromagnetic interference (EMI) shielding effectiveness (above 20 dB) at low filler loadings. Therefore, considerable progress has been achieved with s-CPCs, including high-performance anti-static, EMI shielding and sensing materials. Currently, however, few systematic reviews summarizing these advances with s-CPCs are available. To understand and efficiently harness the abilities of s-CPCs, we attempted to review the major advances available in the literature. This review begins with a concise and general background on the morphology and fabrication methods of s-CPCs. Next, we investigate the ultralow percolation behaviors of and the elements exerting a relevant influence (e.g., conductive filler type, host polymers, dispersion methods, etc.) on s-CPCs. Moreover, we also briefly discussed the latest advances in the mechanical, sensing, thermoelectric and EMI shielding properties of the s-CPCs. Finally, an overview of the current challenges and tasks of s-CPC materials is provided to guide the future development of these promising materials.