Control of microstructural heterogeneities in carbon nanotube foams

Arrays of aligned carbon nanotubes (CNTs) under compression are known to exhibit a dissipative hysteretic response similar to classical foams. Here, we control the microstructure of the arrays during synthesis using a variable supply of carbon source and catalyst. We control CNT alignment and density along the array height, creating bands of high- and low-density regions. We study the dynamic response of these materials and show the ability to tailor the location and extent of strain localization under compression. We show that the synthesis procedures described herein allow for construction of CNT arrays with improved protection and energy dissipation in impact tests.