Excluded Volume Approach for Ultrathin Carbon Nanotube Network Stabilization: A Mesoscopic Distinct Element Method Study

Abstract

Ultrathin carbon nanotube films have gathered attention for flexible electronics applications. Unfortunately, their network structure changes significantly even under small applied strains. We perform mesoscopic distinct element method simulations and develop an atomic-scale picture of the network stress relaxation. On this basis, we put forward the concept of mesoscale design by the addition of excluded-volume interactions. We integrate silicon nanoparticles into our model and show that the nanoparticle-filled networks present superior stability and mechanical response relative to those of pure films. The approach opens new possibilities for tuning the network microstructure in a manner that is compatible with flexible electronics applications.

Densification of single-walled carbon nanotube films: Mesoscopic distinct element method simulations and experimental validation

“…The relaxation process is particularly fast during the first ns of the evolution. At the microstructure level, relaxation occurs through zipping, 14,20 a topological transformation in which crossed CNTs bind locally on a sub-ns time scale. 40 The bundle aggregates generated this way contain only a few CNTs.…”

“…Thus, the manipulation of the intertube crossing points can be used for developing sensors or flexible electronics devices. 12,13 In the optical domain, pristine films demonstrate antireflection properties, which are destroyed by densification. 14,15 Understanding the densification process at the microstructural level is a necessary step for establishing a structure-property relationship, which opens up the possibility of making more informed structural modifications toward a specific application.…”

Toward large scale modeling of carbon nanotube systems with the mesoscopic distinct element method

“…Such a choice leaves space for possible algorithm generalizations allowing to incorporate rigid bodies of various sizes, e.g. for modeling systems of CNTs and nanoparticles [28]. The parallelization is based on standard Message Passing Interface (MPI) [29] for distributed memory architectures.…”

Computationally Guided Design of Large-Diameter Carbon Nanotube Bundles for High-Strength Materials

“…The existence of a broad bundle size distribution in the yarn echoes an earlier result, 9 which found a broad range of bundle sizes identified in nanometer-thin single-walled CNT films collected from the FC-CVD furnace. 9 According to mesoscopic distinct element simulations, 9,32,33 the range of bundle sizes originates in the entanglement arising from repulsive interactions, which obstructs further CNT aggregation and formation of adhesion-stabilized cellular networks consisting of more uniform "large" CNT bundles. It is likely that the same entanglement mechanism plays an important role in the stability of the yarn structure.…”

“…A similar analysis was performed on the TEM images of stretched sheets. According to mesoscale simulations, , the stretching process induces densification by creating new bundles aligned along the applied strain direction. To capture the bundle cross-sections, thin lamellae were taken perpendicularly to the direction of applied strain.…”