title: Silica nanoparticle crystals and ordered coatings using lys-sil and a novel coating device.
abstract: Silica nanoparticles with a narrow particle size distribution and controlled diameters of 10-20 nm are synthesized via hydrolysis and hydrothermal aging of tetraethylorthosilicate in an aqueous L-lysine solution. Cryo-transmission electron microscopy (cryo-TEM) reveals that the silica nanoparticles assemble to form close-packed nanoparticle crystals over short length scales on carbon-coated grids. Evaporative drying of the same sols results in nanoparticle stability and remarkable long-range facile ordering of the silica nanoparticles over scales greater than 10 microm. Whereas small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) discount the possibility of a core (silica)-shell (lysine) structure, the possibility remains for lysine occlusion within the silica nanoparticles and concomitant hydrogen bonding effects driving self-assembly. Facile ordering of the silica nanoparticles into multilayer and monolayer coatings over square-centimeter areas by evaporation-induced self-assembly is demonstrated using a novel dip-coating device.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Snyder
authors.forename: J Alex
authors.initials: JA
authors.lastname: Lee
authors.forename: Tracy M
authors.initials: TM
authors.lastname: Davis
authors.forename: L E
authors.initials: LE
authors.lastname: Scriven
authors.forename: Michael
authors.initials: M
authors.lastname: Tsapatsis
mesh_terms: D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D012542:Scattering, Radiation; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide