Peering into the self-assembly of surfactant templated thin-film silica mesophases.

Content Provider	Semantic Scholar
Author	Doshi, Dhaval Gibaud, Alain Goletto, Valerie Lu, Mengcheng Gerung, Henry Ocko, Benjamin M. Han, Sang Myung Brinker, C. Jeffrey
Copyright Year	2003
Abstract	It is now recognized that self-assembly is a powerful synthetic approach to the fabrication of nanostructures with feature sizes smaller than achievable with state of the art lithography and with a complexity approaching that of biological systems. For example, recent research has shown that silica/surfactant self-assembly combined with evaporation (so-called evaporation induced self-assembly EISA) can direct the formation of porous and composite thin-film mesostructures characterized by precise periodic arrangements of inorganic and organic constituents on the 1-50-nm scale. Despite the potential utility of these films for a diverse range of applications such as sensors, membranes, catalysts, waveguides, lasers, nano-fluidic systems, and low dielectric constant (so-called low k) insulators, the mechanism of EISA is not yet completely understood. Here, using time-resolved grazing incidence small-angle X-ray scattering (GISAXS) combined with gravimetric analysis and infrared spectroscopy, we structurally and compositionally characterize in situ the evaporation induced self-assembly of a homogeneous silica/surfactant/solvent solution into a highly ordered surfactant-templated mesostructure. Using CTAB (cetyltrimethylammonium bromide) as the structure-directing surfactant, a two-dimensional (2-D) hexagonal thin-film mesophase (p6mm) with cylinder axes oriented parallel to the substrate surface forms from an incipient lamellar mesophase through a correlated micellar intermediate. Comparison with the corresponding CTAB/water/alcohol system (prepared without silica) shows that, for acidic conditions in which the siloxane condensation rate is minimized, the hydrophilic and nonvolatile silicic acid components replace water maintaining a fluidlike state that avoids kinetic barriers to self-assembly.
Starting Page	285
Ending Page	288
Page Count	4
File Format	PDF HTM / HTML
Alternate Webpage(s)	http://www.unm.edu/~solgel/PublicationsPDF/2003/DoshiPeering2003.pdf
PubMed reference number	13129369v1
Volume Number	125
Issue Number	38
Journal	Journal of the American Chemical Society
Language	English
Access Restriction	Open
Subject Keyword	Acids Bromides CETRIMONIUM BROMIDE Ethanol Kinetics Lasers Nanostructured Materials Non-Small Cell Lung Carcinoma Order (action) Pulmonary Surfactant-Associated Protein C Silicic Acid Siloxanes Small Tissue membrane evaporation sensor (device)
Content Type	Text
Resource Type	Article