Heteroepitaxial formation of aligned mesostructured silica films with large structural periodicities from mixed surfactant systems

Saeko Hayase, Yosuke Kanno, Masatoshi Watanabe, Masahiko Takahashi, Kazuyuki Kuroda, Hirokatsu Miyata

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    7 Citations (Scopus)

    Abstract

    Liquid-crystal phases consisting of cylindrical micelles of amphiphilic block copolymers and silica precursors are epitaxially built up on aligned surface micelles formed by an alkyl-PEO surfactant, Brij56, irrespective of the large difference in the intrinsic structural periodicities resulting in the formation of fully aligned mesostructured silica films with large lattice constants. Brij56 works as an alignment controlling agent on rubbing-treated polyimide through selective adsorption from a precursor solution containing the two surfactants, a block copolymer and Brij56, through strong hydrophobic interactions to form an anisotropic surface micelle structure. Aligned mesostructured silica layers with larger periodicities, which dominantly consist of block copolymers, form on these aligned surface micelles by gradually changing the vertical periodicity keeping the lateral intermicelle distance constant. This can be regarded as a kind of heteroepitaxy because the lattice constant at the surface is different from that of the bulk of the film. On the basis of this new concept, highly aligned mesostructured silica films with structural periodicities as large as 10 nm are successfully formed, which has never been achieved when the block copolymers are used alone as the structure-directing agent. The periodicity of the aligned films can precisely be controlled by an appropriate choice of block copolymers and the mixing ratio of the two surfactants, which increases the opportunity for applications of these films with highly anisotropic mesoscale structure.

    Original languageEnglish
    Pages (from-to)7096-7101
    Number of pages6
    JournalLangmuir
    Volume29
    Issue number23
    DOIs
    Publication statusPublished - 2013 Jun 11

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    ASJC Scopus subject areas

    • Electrochemistry
    • Condensed Matter Physics
    • Surfaces and Interfaces
    • Materials Science(all)
    • Spectroscopy

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