Nagarajan, Sivakumar and Bosworth, Joan K. and Ober, Christopher K. and Russell, Thomas P. and Watkins, James J.. (2008) Simple Fabrication of Micropatterned Mesoporous Silica Films Using Photoacid Generators in Block Copolymers†. Chemistry of Materials, 20 (3). pp. 604-606. ISSN 0897-4756Full text not available from this repository. (Request a copy)
Mesoporous metal oxide films have been the subject of extensive research because of their potential utility in sensors,(1)a microfluidics,(1)b microelectronics, optoelectronics, microelectromechanical systems,(1)c and catalysis.(1)d Many of these applications require the patterning of the mesoporous device layers to integrate other components necessary for intended applications. Patterning of mesoporous materials has been accomplished to date using a broad range of strategies including soft lithography,(2a, 2)c micropen lithography,(2)d ink-jet printing,(2)d micropatterned self-assembled monolayer templating,(2)e photochemical variation in acid concentration,(2)f and surfactant degradation.(2)g,h In all these approaches, mesoscopic structures are prepared through cooperative assembly of the hydrolyzed silica precursor species and organic surfactants or block copolymers in the presence of acid and excess amount of alcohol. The alcohol is required to slow the condensation of tetraethyl orthosilicate (TEOS) to permit adequate time for assembly to occur, which can result in long processing times and incomplete network condensation.(3) Because the structure evolution and precursor condensation occur simultaneously in this approach, the final film morphology cannot be completely prescribed before silica network formation. Moreover, because assembly occurs in solution or in solvated films, rapid diffusion of reactants and catalysts can result in poor resolution of patterning techniques that rely on spatial discrimination. One potential solution is to decouple structure generation from precursor condensation. Such an approach provides the potential for complete definition of desired hierarchical structure in a suitable template followed by precursor condensation to translate the defined architecture into the inorganic network.
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