Silica films self-assembly

Industrial Applications Characterizing inverted micelles electrooptical displays electronic systems for optical information processing (organic photoconductors) " Langmuir-Blodgett films self-assembled monolayer films nano-stmctured silica films vacuum-deposited films Safety/Toxicity No data available... 

Etienne, M. Walcarius, A. 2005. Evaporation induced self-assembly of templated silica and organosilica thin films on various electrode surfaces. Electrochem. Comm. 7 1449-1456. 

Another photochemically based gating system is the one by Brinker and coworkers in which the cis-trans isomerization of azobenzene was applied.69 (Triethoxysilylpropylureido)azobenzene was co-condensed with TEOS by evaporation-induced self-assembly to yield a functionalized mesoporous silica thin film. The propylureidoazobenzene groups inside of the mesopores could then be iso-merized from their stable elongated trans structure to the more compact cis geometry upon UV irradiation. The trans geometry could be recovered by thermal treatment. The authors suggested that the results of the transitions from trans to cis could lead to an increase in pore size of approximately 0.7 nm and an increase of the polarity from 0 to 3 D. This could be applied to regulation of ion transport however, they did not confirm such expectations.69... 

An example of the first approach is the integration of hydrogels into nanostructured silica films by addition of a suitable monomer (e.g., methyl methacrylate, /V-isopropyl acrylamide, etc.) and an initiator for radical polymerization to a solution containing a structure-directing surfactant and a prehydrolyzed silica precursor. During self-assembly, the monomers partition within the hydrophobic core of the surfactant mesophase postsynthesis polymerization (for instance, by UV treatment) followed by solvent washing to remove the surfactant template yields a polymer-silica nanohybrid. 

As powders are unfavorable with respect to the potential applications in nonlinear optics and in the optical characterization of the composites, ordered mono and bifunctionalized organo-silica thin films were prepared through evaporation-induced self-assembly (EISA) and characterized. 

Brinker et al. developed a simple evaporation-induced self-assembly (EISA) process that allows the rapid production of patterned porous or nanocomposite materials in the form of films, fibers, or spheres. Starting from a homogeneous solution of soluble silica and surfactant below the critical micellar concentration, evaporation of ethanol increased surfactant concentration, driving self-assembly of silica-surfactant micelles and their further organization. By... 

B.W. Eggiman, M.P Tate, and H.W. Hillhouse, Rhombohedral Structure of Highly Ordered and Oriented Self-assembled Nanoporous Silica Thin Films. Chem. Mater., 2006, 18, 723-730. 

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