title: Coassembly of metal and titanium dioxide nanocrystals directed by monolayered block copolymer inverse micelles for enhanced photocatalytic performance.
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 (TiO(2)) 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 TiO(2) 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 TiO(2) NCs, followed by the reduction of Ag salts coordinated in the cores of micelles into AgNPs. Hydrophobic TiO(2) 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 TiO(2) NCs into connected nanoparticles, thus leading to a two-dimensionally ordered TiO(2) network in which AgNPs were also self-organized. The enhanced photocatalytic activity of the AgNP-decorated TiO(2) networks by approximately 27 and 44 % over that of Ag-free TiO(2) networks and randomly deposited TiO(2) nanoparticles, respectively, was confirmed by the UV degradation property of methylene blue.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul, Korea.
authors.forename: Himadri
authors.initials: H
authors.lastname: Acharya
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Sung
authors.forename: Insung
authors.initials: I
authors.lastname: Bae
authors.forename: TaeHee
authors.initials: T
authors.lastname: Kim
authors.forename: Dong Ha
authors.initials: DH
authors.lastname: Kim
authors.forename: Cheolmin
authors.initials: C
authors.lastname: Park