Preparation of ultrathin free-standing porous metal films

A new method for preparing ultrathin freestanding porous metal films bearing a dense two dimensional array of pores was investigated. A mixture of hydrophobic silica colloids and a photopolymerizable organic liquid was applied to a water surface, the organic liquid within the resulting mixed layer was photopolymerized and the silica colloids colloids were removed by etching with hydrofluoric acid. These freestanding porous membranes were used as templates to make porous metal membrane by sputtering a thin layer of metal on the polymeric membrane surface followed by oxidative degradation of the polymer. Scanning electron microscopy images of the porous membranes showed a part of the membrane that was supported by the EM grid, while the lower left region was a free suspended pert, which covers the openings of the grid. A stable porous metal film was obtained after thermal decomposition of the polymeric template.