In addition, the influence of the PDA chemical functionality will be explored by surface modification of the organic template. The second part of the project focused on the formation of oriented crystallites of MnO 2 at PDA thin films. There are many practical applications for these materials, such as cathode materials for primary and secondary batteries, oxidation catalysts, ion-exchangers, and separation agents. Thin epitaxial films of these tunnel structures have potential applications as rapid-response, highly selective sensors for ions or small molecules. Therefore, oriented deposition of the tunnels perpendicular to the film was desired.
Products are often poorly crystalline and multiphase, making characterization difficult.
Because it is more readily synthesized at low temperatures and often in a single step by solution methods, a -MnO 2 was chosen as the first system for deposition. A large-scale screening was carried out to determine the best method for the manganese oxide deposition. Unfortunately, due to the high temperature required, those methods that produced the best a -MnO 2 crystals in solution were found to be incompatible with the PDA films. Eventually, a procedure was found in which the PDA film structure was nominally maintained. Glass substrates coated with PDA are exposed to crystallizing solution containing MnSO 4 .