Souier Tewfik, Stefancich Marco, Chiesa Matteo
Laboratory of Energy and Nanosciences, Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates.
Nanotechnology. 2012 Oct 12;23(40):405704. doi: 10.1088/0957-4484/23/40/405704. Epub 2012 Sep 20.
Nanocomposites of aligned multi-walled carbon nanotubes (CNTs) embedded in a polymer matrix yield a unique combination of thermal and electrical properties and mechanical strength. These properties are intimately related to the composite nanostructure and to the growth and processing conditions. The alignment of the tubes, the filling fraction and the contact junction between the nanotubes are key parameters controlling the composite electrical conductivity. For this purpose, a full description of the composite nanostructure is required. Among the non-destructive scanning probe techniques, scanning spreading resistance microscopy is found to be a powerful technique in identifying the carbon nanotubes with true nanometer resolution, thus competing with SEM and TEM imaging. Additionally, the technique provides valuable information about the electrical conduction mechanism within the composite structure. Indeed, by using a controlled contact force and an appropriate model of conduction at the nanoscale, the tip-CNT contact resistance, the CNT intrinsic resistance and the CNT-epoxy-CNT resistance junction are evaluated. This latter is found to be the factor controlling the overall electrical conductivity of the composite.
嵌入聚合物基体中的取向多壁碳纳米管（CNT）纳米复合材料具有热性能、电性能和机械强度的独特组合。这些性能与复合纳米结构以及生长和加工条件密切相关。碳纳米管的取向、填充率以及纳米管之间的接触结是控制复合材料电导率的关键参数。为此，需要对复合纳米结构进行全面描述。在无损扫描探针技术中，扫描扩展电阻显微镜被发现是一种强大的技术，能够以真正的纳米分辨率识别碳纳米管，从而可与扫描电子显微镜（SEM）和透射电子显微镜（TEM）成像相媲美。此外，该技术还能提供有关复合结构内导电机制的有价值信息。实际上，通过使用可控的接触力和纳米尺度下合适的导电模型，可以评估针尖 - 碳纳米管接触电阻、碳纳米管本征电阻以及碳纳米管 - 环氧树脂 - 碳纳米管电阻结。发现后者是控制复合材料整体电导率的因素。
