Preparation of microporous metal membranes by two-step replication of the microstructure of anodic alumina

Porous alumina films have some disadvantages in actual use. The major problems are insufficiency of chemical stability in aqueous conditions and mechanical strength. To avoid these disadvantageous points, a novel technique has been developed to fabricate stable microporous metal films from the anodic alumina, which involves the two-step molding process for replicating the microstructure of the porous anodic alumina. Selective electroless metal deposition at a localized catalyst was adopted, and gave microporous metal membranes with a high aspect ratio > 60. The diameter and number of the micropores could be controlled by selecting the mother structure of anodic alumina. Metal films of pore diameter of 2000-150 A could be obtained by the present method. The microporous membranes demonstrated will be used for many technological and scientific applications, e.g. electrodes, optical devices and chemical sensors in addition to filtration.