Hierarchical nanostructured surface design for robust and flexible multifunctional devices

This paper investigates structural and functional properties of a hierarchical hybrid flexible material with nanostructured surface architecture. These solids comprise of carpet-like arrays of covalently bonded carbon nanotubes (CNT) on the surface of strong and flexible carbon fabric. In-depth analysis of the multi-scale morphology of this structure is provided, with emphasis on structure-property relationships relevant to surface-interaction related applications such as catalysis, sensing, microfluidics and bio-scaffolding devices. A two-step process is used to anchor carbon nanotubes directly on the surface of carbon fiber cloth, and its morphology, structure and surface chemistry analyzed in detail. Surface structure model from structural and physical property measurements predict over 2000 times increase in specific surface area (SSA) of the fabric due to CNT carpet growth. This estimate is in good agreement with direct SSA measurement using Brunauer–Emmett–Teller (BET) gas-adsorption technique, indicating full utilization of the CNT surface sites, which can be used for adsorption, functionalization, thermal or electrical transport. Electrical measurement of these materials shows a systematic increase of sheet conductivity of the fabric with increasing CNT carpet height. These results indicate that this type of material design can combine the structural durability and flexibility of advanced fabrics with the enhanced surface activity of nanomaterials for a wide variety of surface interaction devices of the future