Simple route to gradient concentric metal and metal oxide rings

A simple route to concentric rings of metals or metal oxide was investigated. The gradient concentric polymer rings with unprecedented regularity were self-organized on metal coated Si substrate through the evaporation induced dynamic self-assembly. The rings were utilized as templates for the preparation of ordered metal or metal oxide rings by removing metal oxide between polymer rings. A thick layer of gold was thermally deposited on Si substrates and to ensure good adhesion between Au and Si a 2-mm thick TiO 2 was first evaporated on Si substrates. the sphere was finally brought into contact with Si substrate by the inchworm motor such that a capillary held PMMA solution forms with evaporation rate highest. the periodic organization of PMMA rings makes an intriguing template for producing metal and metal oxide rings. It was observed that the lithography free route allows subsequent preparation of a great variety of metal and metal oxide concentric ring patterns.