title: Custom-made morphologies of ZnO nanostructured films templated by a poly(styrene-block-ethylene oxide) diblock copolymer obtained by a sol-gel technique.
abstract: Zinc oxide (ZnO) nanostructured films are synthesized on silicon substrates to form different morphologies that consist of foamlike structures, wormlike aggregates, circular vesicles, and spherical granules. The synthesis involves a sol-gel mechanism coupled with an amphiphilic diblock copolymer poly(styrene-block-ethylene oxide), P(S-b-EO), which acts as a structure-directing template. The ZnO precursor zinc acetate dihydrate (ZAD) is incorporated into the poly(ethylene oxide) block. Different morphologies are obtained by adjusting the weight fractions of the solvents and ZAD. The sizes of the structure in solution for different sol-gels are probed by means of dynamic light scattering. Thin-film samples with ZnO nanostructures are prepared by spin coating and solution casting followed by a calcination step. On the basis of various selected combinations of weight fractions of the ingredients used, a ternary phase diagram is constructed to show the compositional boundaries of the investigated morphologies. The evolution and formation mechanisms of the morphologies are addressed in brief. The surface morphologies of the ZnO nanostructures are studied with SEM. The inner structures of the samples are probed by means of grazing incidence small-angle X-ray scattering to complement the SEM investigations. XRD measurements confirm the crystallization of the ZnO in the wurtzite phase upon calcination of the nanocomposite film in air. The optical properties of ZnO are analyzed by FTIR and UV/Vis spectroscopy.
authors.affiliation: Lehrstuhl für Funktionelle Materialien, Physikdepartment, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Kuhu
authors.initials: K
authors.lastname: Sarkar
authors.forename: Monika
authors.initials: M
authors.lastname: Rawolle
authors.forename: Eva M
authors.initials: EM
authors.lastname: Herzig
authors.forename: Weijia
authors.initials: W
authors.lastname: Wang
authors.forename: Adeline
authors.initials: A
authors.lastname: Buffet
authors.forename: Stephan V
authors.initials: SV
authors.lastname: Roth
authors.forename: Peter
authors.initials: P
authors.lastname: Müller-Buschbaum
mesh_terms: D008970:Molecular Weight; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D011092:Polyethylene Glycols / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D019345:Zinc Acetate / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D011137:Polystyrenes; D012997:Solvents; C541965:polystyrene-b-poly(ethylene oxide); D011092:Polyethylene Glycols; D019345:Zinc Acetate; D015034:Zinc Oxide
keywords: block copolymers; nanostructures; phase diagrams; sol-gel processes; zinc oxide