Nanostructured Coatings of Inner Surfaces in Microporous Matrixes

Abstract

There is growing interest in the physical properties of extremely small structures. The experimental realisation of new effects relies on the ability to create new types of structures and devices. Our understanding of material processing in the pursuit of ultra-small structures is continually advancing. Sophisticated epitaxial growth and lateral microstructuring techniques have made it possible to realise low-dimensional electronic systems with quantum confined energy structure i.e. quantum wells, quantum wires and quantum dots. Low-dimensional systems can also be obtained by confining a solid or liquid within the nanometer-sized pores of different porous materials (see[1]). Systems with size-selected nanoparticles embedded in a porous matrix via chemical coating have received some attention these past few years. In this case the confined materials penetrate into the pores due to wetting processes. In the case of non-wetting there is the possibility of using a mechanical coating of inner surfaces of porous materials when some external pressure forces non-wetting liquid into the pores[2]. Mechanical coating means that the mechanical energy of the piston forcing the liquids into the pores transforms to the energy of some new surface arising due to filling process (Fig 1). Since the total surface energy is proportional to the highly developed inner surface of the porous matrix, to surface tension of embedded materials and inversely proportional to the characteristic diameters of pores, for very small diameters a relative amount of surface energy may be very large and even comparable with some traditional sources of energy (Fig 1).