title: Composite mesostructures by nano-confinement.
abstract: In a physically confined environment, interfacial interactions, symmetry breaking, structural frustration and confinement-induced entropy loss can play dominant roles in determining molecular organization. Here we present a systematic study of the confined assembly of silica-surfactant composite mesostructures within cylindrical nanochannels of varying diameters. Using exactly the same precursors and reaction conditions that form the two-dimensional hexagonal SBA-15 mesostructured thin film, unprecedented silica mesostructures with chiral mesopores such as single- and double-helical geometries spontaneously form inside individual alumina nanochannels. On tightening the degree of confinement, a transition is observed in the mesopore morphology from a coiled cylindrical to a spherical cage-like geometry. Self-consistent field calculations carried out to account for the observed mesostructures accord well with experiment. The mesostructures produced by confined syntheses are useful as templates for fabricating highly ordered mesostructured nanowires and nanowire arrays.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
authors.forename: Yiying
authors.initials: Y
authors.lastname: Wu
authors.forename: Guosheng
authors.initials: G
authors.lastname: Cheng
authors.forename: Kirill
authors.initials: K
authors.lastname: Katsov
authors.forename: Scott W
authors.initials: SW
authors.lastname: Sides
authors.forename: Jianfang
authors.initials: J
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Tang
authors.forename: Glenn H
authors.initials: GH
authors.lastname: Fredrickson
authors.forename: Martin
authors.initials: M
authors.lastname: Moskovits
authors.forename: Galen D
authors.initials: GD
authors.lastname: Stucky
mesh_terms: D008854:Microscopy, Electron / Q000379:methods; D015394:Molecular Structure; D036103:Nanotechnology