Integrated simulation of active carbon nanotube forest growth and mechanical compression

Carbon nanotube (CNT) forests are CNT populations that self-assemble into vertically oriented cellular arrays during growth. The anisotropic and inhomogeneous morphology of forests arises from complex mechanical interactions between CNTs during their collective growth and influences many forest properties. A time-resolved simulation is developed to model actively growing CNT populations having distributed properties and growth characteristics. The model considers van der Waals (vdW) attraction between neighboring CNTs and allows the growing and deforming CNTs to interact and react based on a balance of forces. Parametric variations of growth rate distribution and CNT occupation density generate variable CNT forest morphology in manners consistent with experimental observations. The forces opposing vdW bonding between contacting CNTs during forest growth are found to diminish with distance from the growth substrate and are proportional to CNT bending stiffness. Axial and transverse compression of simulated forests capture experimentally observed phenomena of coordinated axial buckling, transverse densification, and the foam-like force-displacement response that is typical of CNT forests. This new paradigm in CNT forest modeling may be used as an analytical tool to examine CNT forest growth kinetics, multi-physics CNT forest performance, and the post-synthesis processing and forming of CNT forest microstructures. (C) 2015 Elsevier Ltd. All rights reserved.