Sol−Gel Nanocoating:  An Approach to the Preparation of Structured Materials

Nanocoating, the covering of materials with a layer on the nanometer scale, or covering of a nanoscale entity, to form nanocomposites and structured materials using the sol−gel process is reviewed. Templates from spherical nanoparticles to complex bicontinuous networks are discussed where either the coated material or the structured inorganic hollow frame resulting after removal of the template are of interest in fields of application ranging from information storage to catalysis. The sol−gel procedure allows coating of templates with complex shapes on the micrometer to nanometer scale, which some commonly used coating procedures cannot achieve. In addition, sol−gel coating techniques can be applied to delicate systems without disruption of their structure or functionality, for example, the coating of biocomplexes or organic aggregates, such as organogelators. Three-dimensional structures with elaborate pore architectures, such as polymer membranes and gels, can also be infiltrated with sol−gel solutions to achieve nanocoatings.