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Well-Organized CdS/C<sub>60</sub> in Block Copolymer Micellar Cores
Koh, Haeng-Deog,Lee, Jung-Pil,Lee, Jae-Suk WILEY-VCH Verlag 2009 Macromolecular Rapid Communications Vol.30 No.12
<P>CdS nanoparticles of 4.5 nm diameter were synthesized in poly(2-vinylpyridine) micellar cores which were obtained by solvating a polystyrene-block-poly(2-vinylpyridine) block copolymer in polystyrene-selective toluene. Then, a C<SUB>60</SUB>-toluene solution was dispersed into the CdS micelle solution with stirring. This led to the well-defined organization of two different nanoparticles; specifically: a CdS NP decorated by several/dozens of C<SUB>60</SUB> molecules, because C<SUB>60</SUB> molecules were strongly coordinated with pyridine molecules in the micellar cores by charge-transfer complexation C<EM><SUB>60</SUB><SUP>δ−</SUP></EM>–P2VP<SUP>δ+</SUP>. A harmoniously organized CdS/C<SUB>60</SUB> micellar structure was clearly verified by transmission electron microscopy. Fluorescent quenching of CdS nanoparticles, which was strongly affected by neighboring C<SUB>60</SUB> molecules, was observed.</P><P> <img src='wiley_img/10221336-2009-30-12-MARC200900036-gra001.gif' alt='wiley_img/10221336-2009-30-12-MARC200900036-gra001'> </P> <B>Graphic Abstract</B> <P>C<SUB>60</SUB> molecules were successfully incorporated into free pyridines of CdS-containing poly(2-vinylpyridine) cores of polystyrene-block-poly(2-vinylpyridine) micelles by charge-transfer complexation between C<SUB>60</SUB> molecules and free pyridines. CdS and C<SUB>60</SUB> are shown to be harmoniously well-organized in a micellar core. <img src='wiley_img/10221336-2009-30-12-MARC200900036-content.gif' alt='wiley_img/10221336-2009-30-12-MARC200900036-content'> </P>
Koh, Haeng-Deog,Park, Ji-Woong,Rahman, M. Shahinur,Changez, Mohammad,Lee, Jae-Suk Royal Society of Chemistry 2009 Chemical communications Vol.2009 No.32
<P>The rod-like chains wrap tangentially to the curved interface of the spherical cores of the rod–coil micelles and vesicles that are reversibly interchangeable by varying the polymer concentration.</P> <P>Graphic Abstract</P><P>The authors demonstrate unique self-assembled micelle and vesicle structures using an amphiphilic rod–coil block copolymer in a rod-selective solvent. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b909000b'> </P>
Preparation of Ag-Embedded Polystyrene Nanospheres and Nanocapsules by Miniemulsion Polymerization
Koh, Haeng-Deog,Changez, Mohammad,Lee, Jung-Pil,Lee, Jae-Suk WILEY-VCH Verlag 2009 Macromolecular Rapid Communications Vol.30 No.18
<P>An isopropyl myristate (IPM) biocompatible oil and an IPM solution of dodecanethiol-capped Ag nanoparticles (NPs, 4.5 nm) were used as hydrophobes to suppress the Ostwald ripening of monomer/hydrophobe miniemulsified droplets in a surfactant-stabilized water phase. The formation of non-IPM-encapsulated nanospheres (48 nm) and IPM-encapsulated nanocapsules (90 nm) were precisely controlled by using a water-soluble and an oil-soluble initiator, respectively, in the presence of a pure IPM as a hydrophobe in miniemulsion polymerization. Well-defined PS nanospheres, on which surfaces were coated with Ag NPs (Ag/PS nanospheres, 65 nm), and nanocapsules encapsulating both NPs and IPM liquid phase (Ag-IPM/PS nanocapsules, 115 nm) were made by replacing the hydrophobe from pure IPM with Ag/IPM solution. These nanostructures were characterized by transmission and scanning electron microscopes.</P><P> <img src='wiley_img/10221336-2009-30-18-MARC200900222-gra001.gif' alt='wiley_img/10221336-2009-30-18-MARC200900222-gra001'> </P> <B>Graphic Abstract</B> <P>Ag-coated PS nanospheres (left) and Ag/liquid (isopropyl myristate, IPM)-encapsulated nanocapsules (right) were synthesized by miniemulsion polymerization in the presence of a water-soluble KPS and an oil-soluble AIBN initiator. An IPM solution containing dodecanethiol-capped Ag NPs acts as a hydrophobe to suppress Ostwald ripening of miniemulsified droplets. <img src='wiley_img/10221336-2009-30-18-MARC200900222-content.gif' alt='wiley_img/10221336-2009-30-18-MARC200900222-content'> </P>
Polymeric Nanocapsules Containing Nematic LCs as Hydrophobes in Miniemulsion Polymerization
Koh, Haeng-Deog,Lee, Jae-Suk WILEY-VCH Verlag 2007 Macromolecular rapid communications Vol.28 No.3
<P>The distinct polymeric nanocapsule hybrid-structures consisting of LCs in the core and PMMA or polystyrene in the corona domain were prepared by one-step miniemulsion polymerization. Nematic LCs (4′-pentyl-4-biphenylcarbonitrile and 4′-heptyloxy-4-biphenylcarbonitrile) were especially adopted as hydrophobes that can suppress Ostwald ripening and had an important role to stabilize the miniemulsion droplets and control the size distributions of the latexes. The polymeric nanocapsule structures with narrow size distributions were confirmed by TEM and DLS measurements.</P><P> <img src='wiley_img/10221336-2007-28-3-MARC200600634-gra001.gif' alt='wiley_img/10221336-2007-28-3-MARC200600634-gra001'> </P>
Fabrication of Pt/Au Concentric Spheres from Triblock Copolymer
Koh, Haeng-Deog,Park, Soojin,Russell, Thomas P. American Chemical Society 2010 ACS NANO Vol.4 No.2
<P>Dispersion of an aqueous H<SUB>2</SUB>PtCl<SUB>6</SUB> solution into a trifluorotoluene (TFT) solution of a polystyrene-<I>block</I>-poly(2-vinylpyridine)-<I>block</I>-poly(ethylene oxide) (PS-<I>b</I>-P2VP-<I>b</I>-PEO) triblock copolymer produced an emulsion-induced hollow micelle (EIHM), comprising a water nanodroplet stabilized by PEO, H<SUB>2</SUB>PtCl<SUB>6</SUB>/P2VP, and PS, sequentially. The following addition of an aqueous LiAuCl<SUB>4</SUB> solution into the dispersion led to a coordination of LiAuCl<SUB>4</SUB> and PEO. The resulting spherical EIHM structure was transformed to a hollow cylindrical micelle by the fusion of spherical EIHM with the addition of methanol. This structural transition was reversible by the alternative addition of methanol and TFT. Oxygen plasma was used to generate Pt/Au concentric spheres and hollow cylindrical Pt/Au nano-objects.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-2/nn9016026/production/images/medium/nn-2009-016026_0002.gif'></P>
Molecular Level Ordering in Poly(2‐vinylpyridine)
Changez, Mohammad,Koh, Haeng‐,Deog,Kang, Nam‐,Goo,Kim, Jin‐,Gyu,Kim, Youn‐,Joong,Samal, Shashadhar,Lee, Jae‐,Suk WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.24
<P><B>The reaction between atactic poly(2‐vinylpyridine) and 1,4‐dibromobutane</B> leads to formation of long‐range 3D molecular ordering in polymer chains mainly because the side group (pyridine) of the polymer chain changes to a syndotactic configuration. This may enable the production of functional molecular devices that operate on a 3D atomic scale.</P>
The fabrication of nanopatterns with Au nanoparticles-embedded micelles via nanoimprint lithography
Lee, Jung-Pil,Kim, Eun-Uk,Koh, Haeng-Deog,Kang, Nam-Goo,Jung, Gun-Young,Lee, Jae-Suk IOP Pub 2009 Nanotechnology Vol.20 No.36
<P>We fabricated nanopatterns with Au nanoparticles-embedded micelles (Au-micelles) by self-assembly of block copolymers via nanoimprint lithography. The micelle structure prepared by self-assembled block copolymers was used as a template for the synthesis of Au nanoparticles (Au NPs). Au NPs were synthesized <I>in situ</I> inside the micelles of polystyrene-<I>block</I>-poly(2-vinylpyridine) (PS- <I>b</I>-P2VP). Au-micelles were arranged on the trenches of the polymer template, which was imprinted by nanoimprint lithography. The fabrication of line-type and dot-type nanopatterns was carried out by the combined method. In addition, multilayer nanopatterns of the Au-micelles were also proposed. </P>