Novel fabrication approaches toward nanostructured functional surfaces : from artificial leaves to block copolymer templates

This thesis describes novel approaches for fabrication of nanostructured functional surfaces: a fast molding and curing for reproduction of artificial leaves, facile replication for ceramic nanostructures, one-step self-assembly for sequenced patterns and functional templates of block copolymer. In a first approach, a simple and fast two-step molding process has been demonstrated the successful replication of hierarchical structures on a native leaf surface. Perfluoropolyether (PFPE) negative structures were generated through a fast UV curing to avoid shrinkage of the cells due to loss of water. Subsequently, hierarchical artificial leaf surface structures were produced with high fidelity by UV- and thermal-curing of a ceramic precursor polymer, polyvinylsilazane (PVSZ, SiCN ceramic precursor), mold. Through a molding and curing method involving no lithographic or mechanical machining process, regularly wrinkled ceramic nanostructures could also be achieved. Wrinkled polydimethylsiloxane (PDMS) stamps, generated in a lithography-free way, were used as masters for structure replication onto PVSZ films. The replicated PVSZ wrinkles were fabricated via a molding followed by photopolymerization using a wrinkled PDMS master. The PVSZ replica was converted to a silicon carbonitride (SiCN) ceramic material by pyrolysis at 800°C in a nitrogen atmosphere. Corrugated SiCN ceramic substrates fabricated by a facile replication process using nonlithographic PDMS masters were employed for the directed assembly of block copolymer microdomains. During thermal annealing of a polystyrene-b-polybutadiene (PS-b-PB) diblock copolymer, the material transport was guided by a wrinkled substrate to form regular modulations in the film thickness. As a consequence of the thickness-dependent morphological behavior of cylinder forming block copolymer, the material was guided into sequenced patterns of alternating cylinder (C), perforated lamella (PL), and lamella (L) phases which follow the topography of the substrate. Morphological behavior in thin films of a cylinder-forming PS-b-PB diblock copolymer affected by film preparations and annealing conditions onto corrugated substrates has been studied. Finally, terrace formation and morphological behavior in thin films of a polybutadiene-block-poly(2-vinyl pyridine)-block-poly(tert-butyl methacrylate) (BVT) terblock polymer have been studied