Advanced Functional Materials

Cover image for Vol. 15 Issue 6

June, 2005

Volume 15, Issue 6

Pages 883–1050

    1. Cover Picture: Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors (Adv. Funct. Mater. 6/2005)

      D. W. Green, I. Leveque, D. Walsh, D. Howard, X. Yang, K. Partridge, S. Mann and R. O. C. Oreffo

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200590020

      Biomineralized polysaccharide capsules (see Figure, center, and cover) provide microenvironments for encapsulation of human cells (top left) and biomolecules that lead to tissue formation. Embedded “host” capsules (bottom left) enable spatial separation of cell populations and temporal release of biological factors. Bone matrix formation is demonstrated (bottom right).

    2. Inside Front Cover: Oxidation Conditions for Octadecyl Trichlorosilane Monolayers on Silicon: A Detailed Atomic Force Microscopy Study of the Effects of Pulse Height and Duration on the Oxidation of the Monolayer and the Underlying Si Substrate (Adv. Funct. Mater. 6/2005)

      D. Wouters, R. Willems, S. Hoeppener, C. F. J. Flipse and U. S. Schubert

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200590021

      The influence of pulse height and pulse duration on the local oxidation of self-assembled monolayers of octadecyl trichlorosilane using scanning probe nanolithography is studied (see inside cover). A narrow window is found in which the terminal methyl groups of the monolayer are converted to carboxylic acid groups, as shown in the Figure.

    3. Contents: Adv. Funct. Mater. 6/2005 (pages 883–890)

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200590019

    4. Control of the Homeotropic Order of Discotic Hexa-peri-hexabenzocoronenes (pages 893–904)

      W. Pisula, Ž. Tomović, B. El Hamaoui, M. D. Watson, T. Pakula and K. Müllen

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400391

      Thumbnail image of graphical abstract

      Introducing dove-tailed alkyl chains onto the aromatic core of hexa-peri-hexabenzocoronene derivatives dramatically lowers the isotropization temperature (Ti), allowing thermal processing from the isotropic phase at practical temperatures. The effect of alkyl-chain length on Ti is investigated, as is the importance of a heteroatom in the side chain on the homeotropic self-assembly of the compounds between two surfaces (see Figure) and on a single surface.

    5. Multicolored Electrochromism of a Poly{1,4-bis[2-(3,4-ethylenedioxy)thienyl]benzene} Derivative Bearing Viologen Functional Groups (pages 905–909)

      H. C. Ko, S. Kim, H. Lee and B. Moon

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400556

      Thumbnail image of graphical abstract

      Chemical incorporation of viologen into poly{1,4-bis[2-(3,4-ethylenedioxy)thienyl]benzene} provides plentiful multicolor electrochromism ranging from highly transparent light blue to four other colors, since both the pendant and the backbone have cathodic coloring characteristics and their redox-potential ranges do not overlap.

    6. Preparation of Homogeneously Dispersed Multiwalled Carbon Nanotube/Polystyrene Nanocomposites via Melt Extrusion Using Trialkyl Imidazolium Compatibilizer (pages 910–916)

      S. Bellayer, J. W. Gilman, N. Eidelman, S. Bourbigot, X. Flambard, D. M. Fox, H. C. De Long and P. C. Trulove

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400441

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      Well-dispersed multiwalled carbon nanotube (MWNT)/ polystyrene nanocomposites (see Figure) are prepared via melt extrusion, using trialkylimidazolium tetrafluoroborate (DMHDIm-TFB)-compatibilized MWNTs. Quantification of the nanodispersion was realized via transmission electron microscopy (TEM) and laser scanning confocal microscopy image analysis. The Figure shows a TEM image of polystyrene with 1:1 imidazolium-treated MWNT and the corresponding analysis plot.

    7. Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors (pages 917–923)

      D. W. Green, I. Leveque, D. Walsh, D. Howard, X. Yang, K. Partridge, S. Mann and R. O. C. Oreffo

      Article first published online: 13 APR 2005 | DOI: 10.1002/adfm.200400322

      Thumbnail image of graphical abstract

      Biomineralized polysaccharide capsules (see Figure, center, and cover) provide microenvironments for encapsulation of human cells (top left) and biomolecules that lead to tissue formation. Embedded “host” capsules (bottom left) enable spatial separation of cell populations and temporal release of biological factors. Bone matrix formation is demonstrated (bottom right).

    8. Ellipsometric Characterization of the Optical Constants of Polyfluorene Gain Media (pages 925–933)

      M. Campoy-Quiles, G. Heliotis, R. Xia, M. Ariu, M. Pintani, P. Etchegoin and D. D. C. Bradley

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400121

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      The optical constants of five poly- fluorenes have been deduced using spectroscopic ellipsometry (see Figure) and employed to characterize the waveguiding conditions that hold for thin-film asymmetric slab structures, including cut-off thicknesses (40–70 nm) and confinement factors (between 37 % and 63 %).

    9. Localized Electrochemical Deposition of Copper Monitored Using Real-Time X-ray Microradiography (pages 934–937)

      S.-K. Seol, A.-R. Pyun, Y. Hwu, G. Margaritondo and J.-H. Je

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400514

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      Real-time X-ray microradiography is used to explore the localized electrochemical deposition of a copper structure. The authors show the importance of the distance between the electrode and the growing structure in determining the morphology of the final product and its lateral resolution. Using a two-step procedure, a high-aspect-ratio structure with good lateral resolution has been fabricated (see Figure).

    10. Oxidation Conditions for Octadecyl Trichlorosilane Monolayers on Silicon: A Detailed Atomic Force Microscopy Study of the Effects of Pulse Height and Duration on the Oxidation of the Monolayer and the Underlying Si Substrate (pages 938–944)

      D. Wouters, R. Willems, S. Hoeppener, C. F. J. Flipse and U. S. Schubert

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400534

      Thumbnail image of graphical abstract

      The influence of pulse height and pulse duration on the local oxidation of self-assembled monolayers of octadecyl trichlorosilane using scanning probe nanolithography is studied (see inside cover). A narrow window is found in which the terminal methyl groups of the monolayer are converted to carboxylic acid groups, as shown in the Figure.

    11. Designing a New Generation of Proton-Exchange Membranes Using Layer-by-Layer Deposition of Polyelectrolytes (pages 945–954)

      T. R. Farhat and P. T. Hammond

      Article first published online: 10 MAR 2005 | DOI: 10.1002/adfm.200400318

      Thumbnail image of graphical abstract

      Ultrathin, flexible composite membranes are constructed via the layered assembly of ionically conductive multilayer thin films on a porous polycarbonate membrane. Under ambient conditions, a fuel cell using a poly(ethylene oxide)/poly(acrylic acid) membrane (see Figure) delivers a maximum power density of 16.5 mW cm–2 at a relative humidity of 55 %, close to that of some commercial fuel cells.

    12. Facile Synthesis of Manganese-Loaded Mesoporous Silica Materials by Direct Reaction Between KMnO4 and an In-Situ Surfactant Template (pages 955–960)

      X. Dong, W. Shen, Y. Zhu, L. Xiong and J. Shi

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400430

      Thumbnail image of graphical abstract

      Manganese-containing mesoporous silica has been prepared by the in-situ reduction of KMnO4 by a surfactant template in the pores of the mesoporous material. These materials exhibit a high catalytic activity for CO oxidation: complete conversion can be achieved at around 300 °C. Furthermore, the catalyst is stable and can be used repeatedly (see Figure).

    13. Synthesis, Functionalization, and Bioconjugation of Monodisperse, Silica-Coated Gold Nanoparticles: Robust Bioprobes (pages 961–967)

      S. H. Liu and M. Y. Han

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400427

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      Monodisperse Au@SiO2nanoparticles (see Figure) are prepared via a facile synthesis. After functionalization and bioconjugation, the particles are used for the fast, colorimetric detection of DNA and protein, based on the sequence-specific hybridization properties of DNA and the specific binding affinity between proteins, respectively.

    14. Electrical Properties and Structure of p-Type Amorphous Oxide Semiconductor xZnO·Rh2O3 (pages 968–974)

      T. Kamiya, S. Narushima, H. Mizoguchi, K. Shimizu, K. Ueda, H. Ohta, M. Hirano and H. Hosono

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400046

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      xZnO·Rh2O3 (x = 0.5–2.0) comprise the only p-type amorphous oxide semiconductors found to date. Their atomic structures, electronic structures, and carrier-transport properties are examined in relation to their chemical composition. All the films exhibit carrier-transport properties similar to those of crystalline ZnRh2O4. The electronic structure of an amorphous oxide p/n junction is also discussed.

    15. Mechanical Properties of Functionalized Single-Walled Carbon-Nanotube/Poly(vinyl alcohol) Nanocomposites (pages 975–980)

      L. Liu, A. H. Barber, S. Nuriel and H. D. Wagner

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400525

      Thumbnail image of graphical abstract

      Functionalized-carbon-nanotube-based poly(vinyl alcohol) composites have been prepared through simple mixing. The nanotubes and the matrix strongly interact, and significant mechanical improvement is obtained on the addition of even small amounts of functionalized nanotubes to the polymer (see Figure for tensile modulus), which reflects the efficient matrix-to-tube load transfer.

    16. Suppression of Green Emission in a New Class of Blue-Emitting Polyfluorene Copolymers with Twisted Biphenyl Moieties (pages 981–988)

      S.-F. Lim, R. H. Friend, I. D. Rees, J. Li, Y. Ma, K. Robinson, A. B. Holmes, E. Hennebicq, D. Beljonne and F. Cacialli

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400457

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      A novel class of polyfluorenes are functionalized so as to increase the biphenyl twist angle. The optical and electroluminescence properties of these materials demonstrate suppression of the well-known green emission band. The Figure demonstrates the progression of the photoluminescence spectra of a copolymer of a non-substituted polyfluorene and an oxepin-functionalized polyfluorene (PF6-O) for increasing proportions of the oxepin moiety.

    17. Fabrication and Surface Functionalization of Nanoporous Gold by Electrochemical Alloying/Dealloying of Au–Zn in an Ionic Liquid, and the Self-Assembly of L-Cysteine  Monolayers (pages 989–994)

      J.-F. Huang and I.-W. Sun

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400382

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      A nanoporous gold electrode has been fabricated via electrochemical alloying/dealloying of Au–Zn in a ZnCl2-based ionic liquid (see Figure). This electrode is functionalized by the self-assembly of L-cysteine monolayers on its surface, showing excellent performance for detecting Cu(II) ions in aqueous solution.

    18. Electrochromic Polymer-Dispersed Liquid-Crystal Film: A New Bifunctional Device (pages 995–999)

      F. P. Nicoletta, G. Chidichimo, D. Cupelli, G. De Filpo, M. De Benedittis, B. Gabriele, G. Salerno and A. Fazio

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400403

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      Bifunctional devices based on polymer-dispersed liquid crystals, which host electrochromic guest molecules, have been prepared (see Figure) and investigated. Such devices allow both an independent and fast switching from a scattering opaque state to a transmissive transparent state, and a color change from white (or pale yellow) to dark blue.

    19. Studies on the Reorganization of Extended Defects with Increasing n in the Perovskite-Based La4Srn–4TinO3n+2 Series (pages 1000–1008)

      J. Canales-Vázquez, M. J. Smith, J. T. S. Irvine and W. Zhou

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400362

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      A new family of layered perovskites, with the formula La4Srn–4TinO3n+2, has been investigated in order to understand the mechanism of incorporating excess oxygen into perovskite lattices. The structure evolves from well-defined layered phases (see Figure a) to cubic phases (see Figure b), where the excess oxygen is accommodated within the perovskite framework in randomly distributed short-range linear defects.

    20. Morphological and Chemical/Physical Characterization of Fe-Doped Synthetic Chrysotile Nanotubes (pages 1009–1016)

      E. Foresti, M. F. Hochella Jr., H. Kornishi, I. G. Lesci, A. S. Madden, N. Roveri and H. Xu

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400355

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      Fe-doped synthetic chrysotile nanotubes have been prepared, with morphologies readily controlled by the amount of Fe present. Increasing Fe content leads to decreased crystallinity and a flatter structure. Chrysotile nanocrystals usually form “cylinder-in-cylinder” arrangements (see Figure), and, interestingly, repeatedly form flat aggregates consisting of four individual tubes when containing higher than 0.57 wt.-% Fe.

    21. Low-Voltage, High-Performance Organic Field-Effect Transistors with an Ultra-Thin TiO2 Layer as Gate Insulator (pages 1017–1022)

      L. A. Majewski, R. Schroeder and M. Grell

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400570

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      Solution-based anodization of titanium offers the possibility of exceptionally cheap manufacture of high-quality, ultra-thin TiO2 films on plastic substrates. In conjunction with organic semiconductors, such thin films can be employed to produce transistors operating well below 1 V. The simplicity of the process (see Figure) makes the commercialization and integration of these devices in inexpensive, disposable, flexible, and mobile products possible.

    22. Organic Spin Ladders from Tetrathiafulvalene (TTF) Derivatives (pages 1023–1035)

      X. Ribas, M. Mas-Torrent, A. Pérez-Benítez, J. C. Dias, H. Alves, E. B. Lopes, R. T. Henriques, E. Molins, I. C. Santos, K. Wurst, P. Foury-Leylekian, M. Almeida, J. Veciana and C. Rovira

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400407

      Thumbnail image of graphical abstract

      Using the first organic spin ladder, a dithiophene-tetrathiafulvalene salt ((DT-TTF)2[Au(mnt)2] (mnt = maleonitriledithiolate)), as a model compound, two approaches to obtain new spin-ladder magnetic systems are described. Modification of the acceptor complex produces new organic spin ladders (structure and electron paramagnetic resonance spin susceptibility shown in Figure).

    23. Water-Stable, Magnetic Silica–Cobalt/Cobalt Oxide–Silica Multishell Submicrometer Spheres (pages 1036–1040)

      V. Salgueiriño-Maceira, M. Spasova and M. Farle

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400469

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      A new method for synthesizing water-stable, magnetic multishell colloids has been designed. It combines the well-known advantages of the layer-by-layer self-assembly of polyelectrolytes and the adsorption of in-situ-produced metallic clusters, offering interesting possibilities for the design of composite core–shell particles (see Figure).

    24. A New Sol–Gel Material Doped with an Erbium Complex and Its Potential Optical-Amplification Application (pages 1041–1048)

      L.-N. Sun, H.-J. Zhang, L.-S. Fu, F.-Y. Liu, Q.-G. Meng, C.-Y. Peng and J.-B. Yu

      Article first published online: 27 MAY 2005 | DOI: 10.1002/adfm.200400386

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      The optical-amplification potential of an erbium complex, formed in-situ in a gel, is discussed. The properties of the erbium-doped gel are investigated, and compared to those of the pure complex. Experimental data (from infrared, diffuse reflectance, and fluorescence spectroscopy) and a theoretical, Judd–Ofelt analysis (see Figure) are used to highlight the potential this new gel has for telecommunications applications.

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