A Unified View on Nanoscale Packing, Connectivity, and Conductivity of CNT Networks

Abstract

The design of functional structures from primary building blocks requires a thorough understanding of how size, shape, and particle-particle interactions steer the assembly process. Specifically, for electrically conductive networks build from carbon nanotubes (CNTs) combining macroscopic characterization and simulations shows that the achievable conductivity is mainly governed by CNT aspect ratio, length dispersity and attractive interactions. However, a direct link between the actual 3D network topology that leads to the observed electrical conductivity has not been established yet due to a lack in nanoscale experimental approaches. Here it is shown experimentally for randomly packed (jammed) CNT networks that the CNT aspect ratio determines, as theoretically predicted, the contact number per CNT which in turn scales linearly with the resulting electrical conductivity of the CNT network. Furthermore, nanoscale packing density, contact areas, contact distribution in random and nonrandom configurations, and least resistance pathways are quantified. The results illustrate how complex nanoscale networks can be imaged and quantified in 3D to understand and model their functional properties in a bottom-up fashion.

State of the‐Art for Extrudate Swell of Molten Polymers: From Fundamental Understanding at Molecular Scale toward Optimal Die Design at Final Product Scale

“…[93] Of course, the filler-matrix interaction needs to be sufficiently strong to enable an acceptable degree of dispersion quality. [94][95][96][97] It is further recommended to verify the impact on other macroscopic properties. [75,[98][99][100][101] It has been additionally indicated that the extrudate swell is influenced by the filler shape as well.…”

Aligned carbon nanotube morphogenesis predicts physical properties of their polymer nanocomposites

“…Recent work on three-dimensional morphological quantification 45,46 and modeling of CNS reinforced polymers 47,48 has shown that a significant amount of stochastically-varying local curvature is exhibited by the CNSs present in the polymer matrix. 45 These works also show that such structural randomness leads to the formation of a large number of van der Waals dominated junctions that may contribute to the mechanical and transport properties of such architectures.…”

“…3D descriptions of CNS morphologies in nanocomposites have recently been provided using quantitative electron tomography 45,46 and small angle X-ray scattering. 50 Specifically, we have developed an electron tomographic Fig.…”

Global and local conductivity in percolating crosslinked carbon black/epoxy–amine composites

“…Considering the option to model I-V curves, either macroscopically or in C-AFM, it will be clear that full details on the complete path between the one electrode (or tip) and the other electrode are required, which so far have not been obtained. Simulations with an effective (constant) contact resistance, taking the various pathways into account as done for carbon nanotube composites [32], will thus be (highly) approximate, as shown in this paper for CB composites, because the contact nature (and area) will vary considerably. We note that papers dealing with the electrical conduction of carbonaceous particulate polymer composites (see, e.g., refs.…”