A Layer-by-Layer Amplifier

Abstract

Materials Science![Figure][1] CREDIT: FANG ET AL., J. MATER. CHEM. 22 , 1305 (2012) A number of biological specimens, such as butterfly wings or diatom frustules, have been used as templates for making optical, catalytic, or electrical materials. This requires a process that conformally coats the template while retaining its detailed features. Diatom frustules are of particular interest because each species generates a unique shell morphology. Fang et al. have developed a wet chemical process to convert the silica shell wall into free-standing copper or nickel structures. The key steps are functionalization of the hydroxyl-bearing surfaces with an aminosilane, followed by layer-by-layer deposition of polyacrylate and polyamine, which amplifies the concentration of surface amines. The structures are then treated with palladium chloride, which acts as a catalyst for the electroless deposition of copper or nickel. The fidelity of the original diatom structures was greatly enhanced through the use of this layer-by-layer amplification technique, with deposition of much finer metal particles and almost no loss of the original template features. The authors were able to extend the process to multilayered copper/gold structures or multicomponent nickel/phosphorus alloys. J. Mater. Chem. 22 , 1305 (2012). [1]: pending:yes