Giant nanomembrane

Membrane, which is self-supporting by definition, separates two spaces of either liquid or solid states, and controls transport of materials and information across them. Its importance in various industrial applications need not be emphasized anew. In the biological world, ion channels and other transport functions are essential for maintenance of the living state, and such functions are supported by biological membranes that consist of lipid bilayers and embedded protein molecules with a membrane thickness of 5-10 nm. The nanoscopic thickness of the biological membrane is the basis of the existence of complex molecular organizations on and in the membrane architecture. Such exquisite organizations have not been achieved with purely artificial materials. On the other hand, macroscopic size is, of course, desired for most industrial membranes. Their ideal features would include defect-free, uniform morphology, macroscopic robustness, efficient permeability, and tailor-made selectivity. The combination of complex molecular architecture as in biological membrane and macroscopic, robust morphology of industrial membrane constitutes a research target of far-reaching significance. An approach toward such an ideal membrane is to develop nanometer-thick (molecular size) membranes with macroscopic mechanical stability and to equip them with welldesigned functional units. Polymeric materials and inorganic materials have been used most frequently to fabricate practically interesting membranes, but their thickness basically remained in the micrometer range, and they involved little organized membrane architectures.