Layer-by-Layer Assembly of Clay–Carbon Nanotube Hybrid Superstructures

Much of the research effort concerning layered materials is directed toward their use as building blocks for the development of hybrid nanostructures with well-defined dimensions and behavior. Here, we report the fabrication through layer-by-layer deposition and intercalation chemistry of a new type of clay-based hybrid film, where functionalized carbon nanotubes are sandwiched between nanometer-sized smectite clay platelets. Single-walled carbon nanotubes (SWCNTs) were covalently functionalized in a single step with phenol groups, via 1,3-dipolar cycloaddition, to allow for stable dispersion in polar solvents. For the production of hybrid thin films, a bottom-up approach combining self-assembly with Langmuir-Schaefer deposition was applied. Smectite clay nanoplatelets act as a structure-directing interface and reaction media for grafting functionalized carbon nanotubes in a bidimensional array, allowing for a controllable layer-by-layer growth at a nanoscale. Hybrid clay/SWCNT multilayer films deposited on various substrates were characterized by X-ray reflectivity, Raman, and X-ray photoelectron spectroscopies, as well as atomic force microscopy.