Geometry‐Induced Mechanical Properties of Carbon Nanotube Foams

Abstract

Carbon nanotube (CNT) foams have unmatched energy absorption properties derived from their complex hierarchical structure. The control of the micro‐scale geometry of these foams allows tuning their behavior to specific application‐driven needs. Geometrical structures in CNT foams are obtained by synthesizing CNTs on substrates patterned with different growth templates: circles, lines and concentric rings. To study the effects of the microstructural geometry on the bulk mechanical response of the foams, the samples are tested under cyclic quasi‐static compressive deformation (up to 50% strain). The geometry of the patterns plays a fundamental role on the samples' macroscopic energy absorption capability, maximum stress, and strain recovery. Patterned CNT structures demonstrated mechanical properties comparable or improved over non‐patterned, bulk CNT foams, but with much lower density. Quasi‐static compressive tests performed on different patterned structures with the same effective density (ρ = 0.02 g cm−3) exhibit considerably different responses. For example, the stress reached by foams patterned in concentric rings is ≈15 times higher than that observed for pillars and lines. The results show how the mechanical response of CNT foams can be tailored by varying the CNT microstructural architecture.