Forming nanomaterials as layered functional structures toward materials nanoarchitectonics

Abstract

Although progress in nanotechnology is anticipated to stimulate the development of innovative materials, the areas of nanotechnology and materials science are somehow separated with little common ground in current technologies. Nanotechnology has some analytical aspects that are beneficial mainly to the nanoscopic sciences at the atom or molecular levels. Experience of these advanced techniques has only been applied in synthetic approaches to macroscopic materials in rather immature level. Forming nanomaterials into hierarchic and organized structures is a rational way of preparing advanced functional materials. Recently, one of us coined the term materials’ nanoarchitectonics to express this innovation. This review focuses on recent research to develop functional materials by forming nanomaterials into organized structures, especially in well-ordered layered structural motifs. This layered nanoarchitectonics can be achieved by using the versatile technology of layer-by-layer assembly. Reassembly of bulk materials into novel layered structures through layered nanoarchitectonics has created many innovative functional materials in a wide variety of fields as can be seen in ferromagnetic nanosheets, sensors, flame-retardant coatings, transparent conductors, electrodes and transistors, walking devices, drug release surfaces, targeting drug carriers and cell culturing. The properties of a material depend on its architecture — this is perhaps best exemplified by the dramatically different behaviours of graphite, graphene and carbon nanotubes. With the advent of nanotechnology, arranging materials into specific, organized structures at the nanoscale has become increasingly important. This issue is discussed here by Katsuhiko Ariga and co-workers, who emphasize the versatility of the layer-by-layer technique. Sheets are first separated from the bulk and assembled differently, sometimes with other components. They can be layered on substrates through electrostatic interactions but also covalent, coordination or hydrogen bonds, and the layer-by-layer procedure can also be carried out in different ways, such as dipping, spin coating or spraying. All of this enables the formation of structures with a wide variety of morphologies, properties and applications, including in the biomedical field. Forming nanomaterials into hierarchic and organized structures is a rational way of preparing advanced functional materials. The term nanoarchitectonics can express this innovation. This review focuses on recent researches to develop functional materials by forming nanomaterials into organized structures, especially in well-ordered layered structural motifs. This layered nanoarchitectonics can be achieved by using the versatile technology of layer-by-layer assembly. Reassembly of bulk materials into novel layered structures through layered nanoarchitectonics has created many innovative functional materials in a wide variety of fields as can be seen in ferromagnetic nanosheets, sensors, flame-retardant coatings, transparent conductors, electrodes and transistors, walking devices, drug release surfaces, targeting drug carriers and cell culturing.