Advanced Materials

Cover image for Vol. 17 Issue 10

May, 2005

Volume 17, Issue 10

Pages 1211–1306

    1. Cover Picture: Functionalized Gold Nanoparticles Mimic Catalytic Activity of a Polysiloxane-Synthesizing Enzyme (Adv. Mater. 10/2005)

      D. Kisailus, M. Najarian, J. C. Weaver and D. E. Morse

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200590051

      A synthetic analogue of a naturally occurring enzyme has been produced by grafting appropriate nucleophilic and hydrogen-bonding functionalities to gold nanoparticles via self-assembled monolayers (see Figure and cover). The synthetic analogue mimics silicatein proteins, which act as both catalysts and templates for formation of silica needles in a marine sponge, converting silicon alkoxide precursors to silica at low temperatures and near-neutral pH.

    2. Inside Front Cover: Self-Organization of Semiconducting Polysiloxane-Phthalocyanine on a Graphite Surface (Adv. Mater. 10/2005)

      P. Samorí, H. Engelkamp, P. A. J. de Witte, A. E. Rowan, R. J. M. Nolte and J. P. Rabe

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200590052

      Functionalized phthalocyaninato-polysiloxanes can self-organize at surfaces into ordered rod-like architectures with a molecular cross-section, both at the solid-liquid interface and in dry films after thermal treatment. The hundreds of nanometer long semiconducting cylinders (see Figure and inside cover) with high apparent stiffness are good candidates as molecular nanowires for future molecular scale electronics.

    3. Grain-to-Grain Stress Interactions in an Electrodeposited Iron Coating (pages 1221–1226)

      Y.-D. Wang, R. L. Peng, J. Almer, M. Odén, Y.-D. Liu, J.-N. Deng, C.-S. He, L. Chen, Q.-L. Li and L. Zuo

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401420

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      Lattice strain distributions mapped by high energy X-ray diffraction (see Figure) in an electrodeposited iron coating with nanocrystalline grains show high nonlinearity, providing unambiguous evidence for the existence of a strong stress interaction along the growth/deposition direction in a layered material.

    4. Reversible-Photon-Mode Full-Color Display by Means of Photochemical Modulation of a Helically Cholesteric Structure (pages 1226–1229)

      T. Yoshioka, T. Ogata, T. Nonaka, M. Moritsugu, S.-N. Kim and S. Kurihara

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401429

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      Photochemical modulation of the selective reflection of cholesteric liquid crystals over a wide range of the visible spectrum is achieved using the E–Z photoisomerization of compounds that have multiple chiral sites and azobenzene groups in the same molecule. The aspect ratio of the photoisomerizable compounds is important for changing the twisting ability of the azobenzene compounds. Blue, green, and red color patterning was accomplished with a resolution of 10–70 μm (see Figure).

    5. A Three-Dimensional Porous Silicon p–n Diode for Betavoltaics and Photovoltaics (pages 1230–1233)

      W. Sun, N. P. Kherani, K. D. Hirschman, L. L. Gadeken and P. M. Fauchet

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401723

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      Three-dimensional porous silicon p–n diodes made by standard industrial processing (see Figure) result in an energy-conversion layer with a large surface/volume ratio. This structure increases radioisotope energy-conversion efficiency tenfold, and could lead to a practical nuclear battery that lasts for many years. Experimental results also show marked photovoltaic response.

    6. Functionalized Gold Nanoparticles Mimic Catalytic Activity of a Polysiloxane-Synthesizing Enzyme (pages 1234–1239)

      D. Kisailus, M. Najarian, J. C. Weaver and D. E. Morse

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401109

      Thumbnail image of graphical abstract

      A synthetic analogue of a naturally occurring enzyme has been produced by grafting appropriate nucleophilic and hydrogen-bonding functionalities to gold nanoparticles via self-assembled monolayers (see Figure and cover). The synthetic analogue mimics silicatein proteins, which act as both catalysts and templates for formation of silica needles in a marine sponge, converting silicon alkoxide precursors to silica at low temperatures and near-neutral pH.

    7. Enhanced Nonlinear Transmittance by Complementary Nonlinear Mechanisms: A Reverse-Saturable Absorbing Dye Blended with Nonlinear-Scattering Carbon Nanotubes (pages 1239–1243)

      S. Webster, M. Reyes-Reyes, X. Pedron, R. López-Sandoval, M. Terrones and D. L. Carroll

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401772

      Thumbnail image of graphical abstract

      A nonlinear transmitting device combining a reverse-saturable absorbing dye and nonlinearly scattering suspended carbon nanotubes offers superior performance over the constituent materials. The composite system is dominated by the absorption properties of the dye below the onset of nonlinear scattering from the nanotubes, but above the onset, the dye becomes saturated and nonlinear scattering dominates (see Figure), thus providing additional protection.

    8. Fabrication of Three-Dimensional Surface Structures with Highly Fluorescent Quantum Dots by Surface-Templated Layer-by-Layer Assembly (pages 1243–1248)

      D. Zhou, A. Bruckbauer, C. Abell, D. Klenerman and D.-J. Kang

      Version of Record online: 4 APR 2005 | DOI: 10.1002/adma.200401520

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      A facile, parallel, and controllable approach to fabricating three-dimensional microscale structures with highly fluorescent quantum dots (QDs) over centimeter-sized surface regions is presented. Highly selective layer-by-layer assembly on a surface patterned by microcontact printing produces features of up to twenty QD/polymer bilayers. Hierarchical structures such as (green-QD/red-QD)n (see Figure) and (QD1/polymer)n(QD1/QD2)m are also fabricated.

    9. Porous-Silicon/Polymer Nanocomposite Photonic Crystals Formed by Microdroplet Patterning (pages 1249–1251)

      Y. Y. Li, V. S. Kollengode and M. J. Sailor

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401760

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      A simple method to construct composite microparticles consisting of porous-silicon one-dimensional photonic crystals infused with a polymer is described. The particles (see Figure) are generated by spray-coating a fine mist of polymer solution onto a photonic crystal layer and then removing the uncoated material by chemical dissolution.

    10. Ferrocene-Functionalized Cationic Polythiophene for the Label-Free Electrochemical Detection of DNA (pages 1251–1254)

      F. Le Floch, H.-A. Ho, P. Harding-Lepage, M. Bédard, R. Neagu-Plesu and M. Leclerc

      Version of Record online: 24 MAR 2005 | DOI: 10.1002/adma.200401474

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      Specific, sensitive detection of unlabeled target DNA at room temperature is reported. A new, water-soluble, ferrocene-functionalized, cationic polythiophene is synthesized. This conducting polymer, used together with gold-bound peptide nucleic acid (PNA) probes, makes, by a simple electrostatic method, DNA detection possible (see Figure).

    11. Electro-Mechano-Optical Conversions in Pr3+-Doped BaTiO3–CaTiO3 Ceramics (pages 1254–1258)

      X. Wang, C.-N. Xu, H. Yamada, K. Nishikubo and X.-G. Zheng

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401406

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      A new class of praseodymium-doped ceramics simultaneously displays electrostriction (the conversion of electrical energy into mechanical energy), mechanoluminescence, and electroluminescence. For example, red-light emission is produced upon compression (see Figure). These environmentally friendly materials may find application in multifunctional sensors or devices.

    12. Functionalized Arylacetylene Oligomers for Organic Thin-Film Transistors (OTFTs) (pages 1258–1261)

      V. A. L. Roy, Y.-G. Zhi, Z.-X. Xu, S.-C. Yu, P. W. H. Chan and C.-M. Che

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401998

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      Oligo(arylacetylene)-based organic thin-film transistors (OTFTs) possess good structural order and smooth film morphologies, and exhibit field-effect mobilities of 0.3 cm2 V–1 s–1, one of the highest field-effect mobilities reported for an OTFT device that does not possess a self-assembled-layer configuration. The Figure shows the measured output characteristics (drain–source current, IDS versus drain–source voltage, VDS) at different gate voltages (VG).

    13. A Lead-Free High-Curie-Point Ferroelectric Ceramic, CaBi2Nb2O9 (pages 1261–1265)

      H. Yan, H. Zhang, R. Ubic, M. J. Reece, J. Liu, Z. Shen and Z. Zhang

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401860

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      A lead-free high-Curie-point Aurivillius-phase ferroelectric ceramic, CaBi2Nb2O9, has been fabricated by spark plasma sintering (SPS). It has a Curie point (943 °C) that is much higher than previously reported (650 °C). The piezoelectric constant d33 of the SPS textured material was nearly three times that of ordinary-fired (OF) materials and was stable up to 800 °C (see Figure). These textured ceramics are promising candidates for high- temperature piezoelectric applications.

    14. Self-Organization of Semiconducting Polysiloxane-Phthalocyanine on a Graphite Surface (pages 1265–1268)

      P. Samorí, H. Engelkamp, P. A. J. de Witte, A. E. Rowan, R. J. M. Nolte and J. P. Rabe

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401825

      Thumbnail image of graphical abstract

      Functionalized phthalocyaninato-polysiloxanes can self-organize at surfaces into ordered rod-like architectures with a molecular cross-section, both at the solid-liquid interface and in dry films after thermal treatment. The hundreds of nanometer long semiconducting cylinders (see Figure and inside cover) with high apparent stiffness are good candidates as molecular nanowires for future molecular scale electronics.

    15. Buried Linear Extrinsic Defects in Colloidal Photonic Crystals (pages 1269–1272)

      E. Vekris, V. Kitaev, G. von Freymann, D. D. Perovic, J. S. Aitchison and G. A. Ozin

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401764

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      Linear extrinsic defects can be embedded inside the lattice of a silica colloidal photonic-crystal film via a directed self-assembly strategy involving a combination of top–down photolithography and bottom–up colloidal assembly. High-spatial-resolution scanning micro-optical spectroscopy proves to be an effective means of characterizing the photonic crystal properties of the buried defects (see Figure) within the film.

    16. Enhanced Coupling to Slow Photon Modes in Three-Dimensional Graded Colloidal Photonic Crystals (pages 1273–1276)

      G. von Freymann, S. John, V. Kitaev and G. A. Ozin

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200402082

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      Enhanced coupling to slow photon modes at the band-edge of graded three-dimensional, thin-film polymer colloidal photonic crystals (see Figure) is demonstrated. For the gradation, polystyrene latex is etched by exposure to air plasma, yielding a top-to-bottom filling-fraction gradient. By monitoring transmission and corresponding phase spectra upon etching, spectral blue-shifts and enhanced mode coupling are observed. Also, surface roughness is reduced, resulting in higher structural and optical quality colloidal photonic crystals.

    17. Fabrication of Hollow Metal “Nanocaps” and Their Red-Shifted Optical Absorption Spectra (pages 1276–1281)

      J. Liu, A. I. Maaroof, L. Wieczorek and M. B. Cortie

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200500035

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      Cap-shaped metal nanoparticles (see Figure) have optical spectra with significant absorption in the infrared. Such shapes, produced by physical vapor deposition onto a polymer-particle template, can be readily separated from one another provided that deposition is carried out at an inclination to the plane of the template. The effect of composition, angle of deposition, and thickness on the properties of the cap-shaped particles is discussed.

    18. Nanolithographic Electropolymerization of a Precursor Polymer Film to Form Conducting Nanopatterns (pages 1282–1285)

      S. Jegadesan, R. C. Advincula and S. Valiyaveettil

      Version of Record online: 24 MAR 2005 | DOI: 10.1002/adma.200401388

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      Electrochemical nanolithography is used to fabricate conducting nanopatterns by selective oxidative crosslinking of poly(vinylcarbazole) (PVK; see Figure). The stable patterns have line thicknesses of 30–150 nm and heights of 4 nm, depending on the bias voltage and writing speed. The technique is simple, low-cost, and operates in ambient conditions.

    19. Low-Voltage Transistor Employing a High-Mobility Spin-Coated Chalcogenide Semiconductor (pages 1285–1289)

      D. B. Mitzi, M. Copel and S. J. Chey

      Version of Record online: 4 APR 2005 | DOI: 10.1002/adma.200401443

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      In2Se3 thin films are spin-coated using a hydrazinium-precursor approach to yield thin-film transistors (TFTs, see Figure). The highly toxic and explosive solvent hydrazine, previously employed for spin-coating SnS2–xSex films, has also been replaced with a more convenient solvent mixture of ethanolamine and dimethyl sulfoxide. Low-voltage operation (< 8 V) of TFTs based on spin-coated In2Se3 yields mobilities as high as 16 cm2 V–1 s–1 and on/off ratios of 106.

    20. Reversible pH-Responsive Surface: From Superhydrophobicity to Superhydrophilicity (pages 1289–1293)

      X. Yu, Z. Wang, Y. Jiang, F. Shi and X. Zhang

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401646

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      A pH-responsive surface has been fabricated by chemisorption of HS(CH2)9CH3 and HS(CH2)10COOH in an appropriate ratio onto a fractal-like gold structure. The surface exhibits superhydrophobicity in an acidic environment and superhydrophilicity under basic conditions. The Figure (right, top) shows an acid droplet on the gold surface, while the image below it shows a base droplet.

    21. Direct Nanoimprinting of Si Single Crystals Using SiC Molds for Ordered Anodic Tunnel Etching (pages 1293–1295)

      K. Nishio, K. Yasui, F. Matsumoto, K. Kanezawa and H. Masuda

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401879

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      Ordered hole-array structures of Si single crystals (see Figure) are formed by direct imprinting with an SiC mold followed by subsequent anode etching in HF solution. In this process, the ordered array of shallow concaves prepared by direct imprinting can act as starting points for the development of uniform-sized straight holes with high aspect ratios. This process is simple and has a high throughput for the fabrication of ordered Si hole arrays.

    22. Direct Access to Stable, Freestanding Polymer Membranes by Layer-by-Layer Assembly of Polyelectrolytes (pages 1296–1299)

      F. Mallwitz and A. Laschewsky

      Version of Record online: 3 MAY 2005 | DOI: 10.1002/adma.200401123

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      A novel method to prepare ultrathin, freestanding polyelectrolyte films in pores, without the need of sacrificial precursor coatings, has been developed (see Figure). The freestanding films are stable under ambient conditions and suited for additional electrostatic self-assembly or surface modification. They can be specifically decomposed, whereas after thermal crosslinking, resistant films are obtained.

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