Formation of titanium nanostructures on block copolymer templates with varying molecular weights

A novel and simple method for producing mesoporous titanium films and supported titanium nanoparticle hexagonal arrays is presented. During evaporation on block copolymer templates, titanium self-assembles as either a mesoporous film or as a hexagonal close-packed nanodot structure. The morphology of the titanium only depends on the molecular weight of the block copolymer, which results in a remarkable fabrication technique that saves time relative to conventional methods. Analyses using scanning electron microscopy, X-ray reflectometry, and grazing-incidence small-angle X-ray scattering correlate the morphology of the titanium with the buried polymer structure. The mesoporous titanium film exhibited a pore size of approximately 16 nm, with a pore-to-pore distance of 42 nm. The average size of the hexagonally packed nanodots was 60 nm, with a center-to-center distance of 88 nm commensurate with the template features. An analysis of the chemical composition showed that the structures were titanium dioxide, which indicated that oxidation occurred during the fabrication process.
The authors acknowledge financial support from the EU-FP7 Integrated Infrastructure Initiative No. 262348 from the European Soft Matter Infrastructure (ESMI), LAMAND (Grant No. 245565), MERGING (Grant No. 309150), the Spanish MINECO project TAPHOR (MAT2012−31392), and the Deutsche Forschungsgemeinschaft (Grant No. KR 4522/1-1).