Flexible and controllable self-regulating heating devices with positive temperature coefficient (PTC) behaviour are potentially excellent candidates in applications like healthcare, soft robotics, artificial skin and wearable electronics. Although extensive studies have been carried out in this field to understand the mechanism of PTC effect, rather limited conclusions have been reached. Many controversies remain on the dominating factors that influence the PTC performance of composites, hence limiting their design and broader applications. Herein, we propose a systematic study to explore the PTC phenomenon and the underlying mechanism, from a conductive network viewpoint, taking account of both conductive fillers and polymer matrices. Three representative conductive fillers with distinct dimensions and shapes (0D silver coated glass spheres, 1D carbon nanotubes and 2D graphene nanoplatelets), in combination with three different polymer matrices (high density polyethylene, thermoplastic polyurethane and polycarbonate) were selected to elucidate the effect of the “robustness” of different conductive networks on PTC behaviour in conductive polymer composites (CPCs). The desired conductive network can be obtained by selecting preferentially larger filler size, lower filler aspect ratio and/or selective distribution of filler (e.g. in the amorphous region of semi-crystalline polymers). The highest PTC intensity was observed around the “critical” percolation threshold, in correspondence of networks with the lowest number of inter-particle contacts. This study can serve as a guideline in the selection of the most appropriate conductive filler and polymer matrix for various self-regulating heating requirements and final applications.

具有正温度系数（PTC）行为的灵活且可控的自调节加热设备在医疗保健，软机器人，人造皮肤和可穿戴电子设备等应用中可能是极好的选择。尽管在该领域已进行了广泛的研究以了解PTC效应的机理，但得出的结论却相当有限。影响复合材料PTC性能的主要因素仍然存在许多争议，因此限制了它们的设计和更广泛的应用。本文中，我们提出了一项系统研究，从导电网络的角度探讨PTC现象及其潜在机理，同时考虑了导电填料和聚合物基质。三种具有代表性的导电填料，具有不同的尺寸和形状（0D镀银玻璃球，选择一维碳纳米管和二维石墨烯纳米片，并结合三种不同的聚合物基质（高密度聚乙烯，热塑性聚氨酯和聚碳酸酯），以阐明不同导电网络的“稳健性”对导电聚合物复合材料（CPC）中PTC行为的影响）。可以通过优先选择较大的填料尺寸，较低的填料长径比和/或填料的选择性分布（例如在半结晶聚合物的无定形区域中）来获得所需的导电网络。在“临界”渗透阈值附近观察到最高PTC强度，这与具有最少粒子间接触次数的网络相对应。