School of Materials Science and Engineering, The Key Laboratory of Material Processing and Mold of Ministry of Education, Zhengzhou University, Zhengzhou, Henan 450001, China.
Nanoscale. 2016 Jul 14;8(26):12977-89. doi: 10.1039/c6nr02216b. Epub 2016 Jun 15.
Thermoplastic polyurethane (TPU) based conductive polymer composites (CPCs) with a reduced percolation threshold and tunable resistance-strain sensing behavior were obtained through the addition of synergistic carbon nanotubes (CNT) and graphene bifillers. The percolation threshold of graphene was about 0.006 vol% when the CNT content was fixed at 0.255 vol% that is below the percolation threshold of CNT/TPU nanocomposites. The synergistic effect between graphene and CNT was identified using the excluded volume theory. Graphene acted as a 'spacer' to separate the entangled CNTs from each other and the CNT bridged the broad gap between individual graphene sheets, which was beneficial for the dispersion of CNT and formation of effective conductive paths, leading to better electrical conductivity at a lower conductive filler content. Compared with the dual-peak response pattern of the CNT/TPU based strain sensors, the CPCs with hybrid conductive fillers displayed single-peak response patterns under small strain, indicating good tunability with the synergistic effect of CNT and graphene. Under larger strain, prestraining was adopted to regulate the conductive network, and better tunable single-peak response patterns were also obtained. The CPCs also showed good reversibility and reproductivity under cyclic extension. This study paves the way for the fabrication of CPC based strain sensors with good tunability.
通过添加协同的碳纳米管（CNT）和石墨烯双填料，获得了具有降低渗流阈值和可调电阻-应变传感性能的热塑性聚氨酯（TPU）基导电聚合物复合材料（CPCs）。当 CNT 含量固定在 0.255 体积%时，石墨烯的渗流阈值约为 0.006 体积%，低于 CNT/TPU 纳米复合材料的渗流阈值。利用排除体积理论确定了石墨烯和 CNT 之间的协同效应。石墨烯作为“间隔物”，将缠结的 CNT 彼此分离，而 CNT 桥接了各个石墨烯片之间的宽间隙，有利于 CNT 的分散和有效导电路径的形成，从而在较低的导电填料含量下实现更好的导电性。与基于 CNT/TPU 的应变传感器的双峰响应模式相比，具有混合导电填料的 CPCs 在小应变下显示出单峰响应模式，表明具有 CNT 和石墨烯协同效应的良好可调性。在较大应变下，采用预应变来调节导电网络，也获得了更好的可调单峰响应模式。CPCs 在循环拉伸下也表现出良好的可重复性和可恢复性。这项研究为制备具有良好可调性的基于 CPC 的应变传感器铺平了道路。
