Glier Tomke E, Betker Marie, Witte Maximilian, Matsuyama Toru, Westphal Lea, Grimm-Lebsanft Benjamin, Biebl Florian, Akinsinde Lewis O, Fischer Frank, Rübhausen Michael
Institut für Nanostruktur- und Festkörperphysik, Center for Free Electron Laser Science (CFEL), Universität Hamburg, Luruper Chaussee 149, 22761, Hamburg, Germany.
Nanoscale. 2020 Dec 8;12(46):23831-23837. doi: 10.1039/d0nr05734g.
Flexible and conductive silver-nanowire photopolymer composites are fabricated and studied under mechanical strain. The initial resistances of the unstretched flexible composites are between 0.27 Ω mm-1 and 1.2 Ω mm-1 for silver-nanowire concentrations between 120 μg cm-2 and 40 μg cm-2. Stretching of the samples leads to an increased resistance by a factor of between 72 for 120 μg cm-2 and 343 for 40 μg cm-2 at elongations of 23%. In order to correlate network morphology and electrical properties, micrographs are recorded during stretching. The Fiber Image Network Evaluation (FINE) algorithm determines morphological silver-nanowire network properties under stretching. For unstretched and stretched samples, an isotropic nanowire network is found with only small changes in fiber orientation. Monte-Carlo simulations on 2D percolation networks of 1D conductive wires and the corresponding network resistance due to tunneling of electrons at nanowire junctions confirm that the elastic polymer matrix under strain exhibits forces in agreement with Hooke's law. By variation of a critical force distribution the resistance curves are accurately reproduced. This results in a model that is dominated by quantum-mechanical tunneling at nanowire junctions explaining the electrical behavior and the sensitivity of nanowire-composites with different filler concentrations under mechanical strain.
制备了柔性导电银纳米线光聚合物复合材料，并在机械应变下对其进行了研究。对于银纳米线浓度在40 μg cm-2至120 μg cm-2之间的未拉伸柔性复合材料，其初始电阻在0.27 Ω mm-1至1.2 Ω mm-1之间。在23%的伸长率下，样品的拉伸导致电阻增加，对于120 μg cm-2的样品，电阻增加72倍，对于40 μg cm-2的样品，电阻增加343倍。为了关联网络形态和电学性能，在拉伸过程中记录了显微照片。纤维图像网络评估（FINE）算法确定了拉伸过程中银纳米线网络的形态学特性。对于未拉伸和拉伸后的样品，发现了各向同性的纳米线网络，纤维取向仅有微小变化。对一维导线的二维渗流网络以及由于纳米线结处电子隧穿导致的相应网络电阻进行的蒙特卡罗模拟证实，应变下的弹性聚合物基体表现出符合胡克定律的力。通过改变临界力分布，可以准确再现电阻曲线。这就产生了一个模型，该模型以纳米线结处的量子力学隧穿为主导，解释了不同填料浓度的纳米线复合材料在机械应变下的电学行为和灵敏度。
