title: Directed In Situ Shaping of Complex Nano- and Microstructures during Chemical Synthesis.
abstract: Chemical composition and shape determine the basic properties of any object. Commonly, chemical synthesis and shaping follow each other in a sequence, although their combination into a single process would be an elegant simplification. Here, a pathway of simultaneous synthesis and shaping as applied to polysiloxanes on the micro- and nanoscale is presented. Complex structures such as stars, chalices, helices, volcanoes, rods, or combinations thereof are obtained. Varying the shape-controlling reaction parameters including temperature, water saturation, and the type of substrate allows to direct the reaction toward specific structures. A general mechanism of growth is suggested and analytical evidence and thermodynamic calculations to support it are provided. An aqueous droplet in either gaseous atmosphere or in a liquid organic solvent serves as a spatially confined polymerization volume. By substituting the starting materials, germanium-based nanostructures are also obtained. This transferability marks this approach as a major step toward a generally applicable method of chemical synthesis including in situ shaping.
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: Georg R J
authors.initials: GR
authors.lastname: Artus
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: Sandro
authors.initials: S
authors.lastname: Olveira
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Patra
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Seeger
mesh_terms: D008832:Microchemistry / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D012833:Siloxanes / Q000138:chemical synthesis* / Q000737:chemistry; D013499:Surface Properties
chemical_list: D012833:Siloxanes
keywords: in situ shaping; polymers; polysiloxanes; synthesis; vapor-liquid-solid mechanism