Impact of Morphology and Confinement Effects on the Properties of Aligned Carbon Nanotube Architectures

The intrinsic and scale-dependent properties of carbon nanotubes (CNTs) have made them the focus of many application-specific nanostructured materials studies. However, various CNT morphology and proximity effects can lead to > 1000× reductions in the performance of CNT-based material architectures, such as bulk materials and structures comprised of scalable aligned CNT (A-CNT) arrays. The physical and chemical origins of these effects, along with the concomitant structure-property mechanisms of materials comprised of A-CNTs, are not currently known and cannot be properly integrated into existing theories. This originates in part from an incomplete understanding of the morphology of real CNT systems, particularly in three-dimensions. Through experiments, theory, and multi-scale simulation, a framework capable of modeling the stochastic 3D morphology A-CNT arrays is developed, and presented here. Using new descriptions of the CNT morphology, the mechanical behavior of A-CNT arrays, A-CNT polymer matrix nanocomposites (A-PNCs), and A-CNT carbon matrix nanocomposites (A-CMNCs) is explored. The torsion and shear deformation mechanisms, which are governed by the low (< 1 GPa) intrinsic shear modulus of the CNTs, are shown to dominate the deformation mechanics and lead to the previously observed orders of magnitude mechanical property enhancement in A-CNT systems as the CNT volume fraction (Vf) is increased from ~ 1 to 20%. Using these structure-property prediction tools, precise tailoring and prediction of the application-specific performance of A-CNT based architectures is enabled, and future paths of study that could enable the design and manufacture of several classes of next-generation materials are discussed.

For further information please contact james.liddle [at] nist.gov (J. Alex Liddle), 301-975-6050.