title: Gold-decorated block copolymer microspheres with controlled surface nanostructures.
abstract: Gold-decorated block copolymer microspheres (BCP-microspheres) displaying various surface morphologies were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) microspheres. The microspheres were fabricated by emulsifying the PS-b-P4VP polymers in chloroform into a surfactant solution in water, followed by the evaporation of chloroform. The selective swelling of the P4VP domains in the microspheres by the Au precursor under acidic conditions resulted in the formation of Au-decorated BCP-microspheres with various surface nanostructures. As evidenced by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) measurements, dotted surface patterns were formed when microspheres smaller than 800 nm were synthesized, whereas fingerprint-like surface patterns were observed with microspheres larger than 800 nm. Au nanoparticles (NPs) were located inside P4VP domains near the surfaces of the prepared microspheres, as confirmed by TEM. The optical properties of the BCP-microspheres were characterized using UV-vis absorption spectroscopy and fluorescence lifetime measurements. A maximum absorption peak was observed at approximately 580 nm, indicating that Au NPs are densely packed into P4VP domains on the microspheres. Our approach for creating Au-NP-hybrid BCP-microspheres can be extended to other NP systems such as iron-oxide or platinum NPs. These precursors can also be selectively incorporated into P4VP domains and induce the formation of hybrid BCP-microspheres with controlled surface nanostructures.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.
authors.forename: Minsoo P
authors.initials: MP
authors.lastname: Kim
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Kang
authors.forename: Dae-Woong
authors.initials: DW
authors.lastname: Jung
authors.forename: Aravindaraj G
authors.initials: AG
authors.lastname: Kannan
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Kim
authors.forename: Kang Hee
authors.initials: KH
authors.lastname: Ku
authors.forename: Se Gyu
authors.initials: SG
authors.lastname: Jang
authors.forename: Weon-Sik
authors.initials: WS
authors.lastname: Chae
authors.forename: Gi-Ra
authors.initials: GR
authors.lastname: Yi
authors.forename: Bumjoon J
authors.initials: BJ
authors.lastname: Kim
mesh_terms: D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D008863:Microspheres; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D011137:Polystyrenes / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D008823:Micelles; D011137:Polystyrenes; D011145:Polyvinyls; D011725:Pyridines; C509607:polystyrene-block-poly(4-vinylpyridine); D014867:Water; D006046:Gold