Coassembly of Metal and Titanium Dioxide Nanocrystals Directed by Monolayered Block Copolymer Inverse Micelles for Enhanced Photocatalytic Performance

Authors

  • Dr. Himadri Acharya,

    1. Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
    2. Center for Soft Matters, Department of Chemistry, Assam University, Silchar, 788011, Assam (India)
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  • Dr. Jinwoo Sung,

    1. Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
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  • Insung Bae,

    1. Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
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  • Dr. TaeHee Kim,

    1. Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
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  • Dong Ha Kim,

    1. Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, 120-750 (Korea)
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  • Prof. Dr. Cheolmin Park

    Corresponding author
    1. Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
    • Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 (Korea), Fax: (+82) 2-312-5375
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Abstract

Functional nanostructures of self-assembled block copolymers (BCPs) incorporated with various inorganic nanomaterials have received considerable attention on account of their many potential applications. Here we demonstrate the two-dimensional self-assembly of anisotropic titanium dioxide (TiO2) nanocrystals (NCs) and metal nanoparticles (NPs) directed by monolayered poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymer inverse micelles. The independent position-selective assembly of TiO2 NCs and silver nanoparticles (AgNPs) preferentially in the intermicelle corona regions and the core of micelles, respectively, for instance, was accomplished by spin-coating a mixture solution of PS-b-P4VP and ex situ synthesized TiO2 NCs, followed by the reduction of Ag salts coordinated in the cores of micelles into AgNPs. Hydrophobic TiO2 NCs with a diameter and length of approximately 3 nm and 20–30 nm, respectively, were preferentially sequestered in the intermicelle nonpolar PS corona regions energetically favorable with the minimum entropic packing penalty. Subsequent high-temperature annealing at 550 °C not only effectively removed the block copolymer but also transformed the TiO2 NCs into connected nanoparticles, thus leading to a two-dimensionally ordered TiO2 network in which AgNPs were also self-organized. The enhanced photocatalytic activity of the AgNP-decorated TiO2 networks by approximately 27 and 44 % over that of Ag-free TiO2 networks and randomly deposited TiO2 nanoparticles, respectively, was confirmed by the UV degradation property of methylene blue.

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