Elastic shape recovery of carbon nanotube sponges in liquid oil

Abstract

Self-assembled porous nanomaterials are potential candidates for applications such as filtration, adsorption and cleanup, yet their interactions with the surrounding environment and structural stability under external loads or fluid flow have not been adequately studied. Here, we investigated mechanical deformation and shape recovery of bulk carbon nanotube sponges immersed in various liquid oils under repeated compression cycles at large strains (50%). The nanotube sponges show virtually elastic recovery to their original volume (>98%) in the presence of oil, compared to other media such as air or water in which significant plastic deformation occurs. Oil was squeezed out of the sponge pores during compression and then sucked into the sponges to enable structure recovery when load is released, indicating the possibility for recycled oil adsorption. Smooth oil infiltration into the nanotube sponges by laminar flow is a critical factor for maintaining stable isotropic nanotube networks and promoting fast volume expansion with a thickness recovery rate of >10 mm min⁻¹ in low-viscosity oils. Our carbon nanotube sponges might be used in environmental applications such as oil adsorption and spill cleanup with enhanced robustness and recyclability.