Advanced Materials

Cover image for Vol. 14 Issue 12

June, 2002

Volume 14, Issue 12

Pages 859–933

    1. Contents: Adv. Mater. 12/2002 (pages 859–862)

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<859::AID-ADMA859>3.0.CO;2-I

    2. Contents: Adv. Funct. Mater. 6+7/2002 (pages 864–866)

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<864::AID-ADMA864>3.0.CO;2-Y

    3. Calcium Carbonate–Organic Hybrid Materials (pages 869–877)

      T. Kato, A. Sugawara and N. Hosoda

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<869::AID-ADMA869>3.0.CO;2-E

      Synthetic composites with controlled morphologies based on calcium carbonate (see Figure) have been obtained by self-organization processes through molecular interactions between organic and inorganic substances. These hybrid materials with polymers and aligned amphiphilic molecules on the surface are a living example of how highly functionalized materials can be created by environmentally friendly techniques.

    4. Toward Encoding Combinatorial Libraries: Charge-Driven Microencapsulation of Semiconductor Nanocrystals Luminescing in the Visible and Near IR (pages 879–882)

      N. Gaponik, I.L. Radtchenko, G.B. Sukhorukov, H. Weller and A.L. Rogach

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<879::AID-ADMA879>3.0.CO;2-A

      Charge-driven microencapsulation of water-soluble CdTe nanocrystals has been used to create both single-color tagged microspheres (see Figure) and multicolored beads with controlled emission intensity ratios. The concept is based on the pumping of negatively charged species into the interior of specially designed microspheres. CdTe nanocrystals brightly luminescing in the visible and near-IR were used as they are important for further use in encoding combinatorial libraries (see also cover).

    5. Cell Motility and Metastatic Potential Studies Based on Quantum Dot Imaging of Phagokinetic Tracks (pages 882–885)

      W.J. Parak, R. Boudreau, M. Le Gros, D. Gerion, D. Zanchet, C.M. Micheel, S.C. Williams, A.P. Alivisatos and C. Larabell

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<882::AID-ADMA882>3.0.CO;2-Y

      The uptake of colloidal semiconductor nanocrystals by a large range of eukaryotes (see Figure) is directly correlated with the cell motility, as has been shown by comparing the motions of cancerous and healthy human breast cells. The nanocrystals are more photochemically robust than organic dyes and provide a powerful tool for studying the processes of cell motility and migration—behaviors that are responsible for metastases of primary cancers.

    6. Biomaterials to Spatially Regulate Cell Fate (pages 886–889)

      J.A. Rowley, Z. Sun, D. Goldman and D.J. Mooney

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<886::AID-ADMA886>3.0.CO;2-I

      Cell fate can be directed by material-derived signals and an appropriate combination of signals can direct distinct cell fates. Adhesive ligands promote the multiplication of cells in direct contact with the signal, while the calcium gradient resulting from its release spatially regulates the ability of cells to differentiate (see Figure for an example of myoblasts that have formed muscle tissue).

    7. Controlled Location of Porphyrin in Aqueous Micelles Self-Assembled from Porphyrin Centered Amphiphilic Star Poly(oxazolines) (pages 889–892)

      R.-H. Jin

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<889::AID-ADMA889>3.0.CO;2-6

      Polymeric nanomicelles that allow control of the location of porphyrin moieties in the coronas, cores, or cores and coronas have been designed and reliably constructed by self- assembly of porphyrin-centered star polymers (see Figure). These photofunctional nanomicelles are of interest for advanced materials, pharmaceutical, and medical applications.

    8. Enhancement of Photocurrent Generation by ITO Electrodes Modified Chemically with Self-Assembled Monolayers of Porphyrin–Fullerene Dyads (pages 892–895)

      H. Yamada, H. Imahori, Y. Nishimura, I. Yamazaki and S. Fukuzumi

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<892::AID-ADMA892>3.0.CO;2-U

      Porphyrin–fullerene linked systems (see Figure), which form self-assembled monolayers on ITO electrodes, exhibit enhanced photocurrent generation: This is due to a two-step electron transfer protocol—first intramolecularly from 1P to C60, then intermolecularly from the resulting C60• – to the electron carriers.

    9. Magnetic Nanocomposites Built by Controlled Incorporation of Magnetic Clusters into Mesoporous Silicates (pages 896–898)

      T. Coradin, J. Larionova, A.A. Smith, G. Rogez, R. Clérac, C. Guérin, G. Blondin, R.E.P. Winpenny, C. Sanchez and T. Mallah

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<896::AID-ADMA896>3.0.CO;2-E

      Nanomagnets have been created by the incorporation of magnetic clusters into mesoporous silica. It is shown that, for a given cluster, the pore size has a strong influence on the degree of incorporation. Furthermore, the incorporation of these nanoclusters into three-dimensional organized mesoporous silica ensures that the integrity of the host phase as well as that of the incorporated clusters is maintained. This high degree of stability opens new perspectives for the organization of nanomagnets into mesoporous silica layers or as monolayers on silica surfaces.

    10. Self-Assembly of Carbon Nanotubes (pages 899–901)

      H. Shimoda, S.J. Oh, H.Z. Geng, R.J. Walker, X.B. Zhang, L.E. McNeil and O. Zhou

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<899::AID-ADMA899>3.0.CO;2-2

      Films of single-walled carbon nanotubes have been obtained by simple evaporation of suspended nanotubes on a glass substrate. The technique has also been used to create patterned structures (see Figure) by treating the substrate before evaporation and thus creating hydrophobic and hydrophilic areas. The films showed orientational ordering, which could be useful for optical applications.

    11. Layer-by-Layer Assembly of Polythiophene (pages 901–905)

      L. Zhai and R.D. McCullough

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<901::AID-ADMA901>3.0.CO;2-T

      Layer-by-layer deposition of polythiophene (see Figure) has successfully been carried out using only polyanion and polycation dilute solutions of polythiophene. The synthesis and characterization of these assemblies, as well as their optical properties, are described. The conductivities of the regioregular polythiophenes reported are much higher than for regiorandom polythiophene multilayer systems.

    12. Development of Metal Oxide Nanoparticles with High Stability Against Particle Growth Using a Metastable Solid Solution (pages 905–908)

      E.R. Leite, A.P. Maciel, I.T. Weber, P.N. Lisboa-Filho, E. Longo, C.O. Paiva-Santos, A.V.C. Andrade, C.A. Pakoscimas, Y. Maniette and W.H. Schreiner

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<905::AID-ADMA905>3.0.CO;2-D

      Nanometer-size tin oxide particles (see Figure) with high thermal stability against particle growth have been synthesized. A low particle growth rate was achieved by doping SnO2 particles with rare earth ions during synthesis. This technology can be applied to modify the particle surface and then control growth rate and specific electric and catalyst properties, producing nanostructured materials with improved performance.

    13. Gold–Silica Inverse Opals by Colloidal Crystal Templating (pages 908–912)

      D. Wang, V. Salgueiriño-Maceira, L.M. Liz-Marzán and F. Caruso

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<908::AID-ADMA908>3.0.CO;2-1

      Metallodielectric inverse opal films (see Figure) have been fabricated by templating colloidal crystals with gold–silica core–shell nanoparticles. The degree of packing order of the inverse opals was determined by the Au@SiO2 nanoparticle diameter. The technique provides a highly versatile means of tuning the inverse opal properties through variation of the silica coating on the nanoparticle building blocks.

    14. Pore-Controlled Proton Conducting Silica Films (pages 912–914)

      H. Li and M. Nogami

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<912::AID-ADMA912>3.0.CO;2-L

      Highly proton-conducting glass films have been prepared by controlling the pore size of the silica film. The conductivity of films with pores perpendicular to the substrate surface is high, whereby the conductivity increases with increasing water content. The high conductivity was retained at relatively low humidity due to the restriction of water movement in the pores. These porous proton-conducting materials are of interest for use in small fuel cell systems.

    15. High-Performance, Flexible Polymer Light-Emitting Diodes Fabricated by a Continuous Polymer Coating Process (pages 915–918)

      J. Ouyang, T.-F. Guo, Y. Yang, H. Higuchi, M. Yoshioka and T. Nagatsuka

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<915::AID-ADMA915>3.0.CO;2-9

      Large-area polymer thin films of adjustable thickness have been prepared by a continuous bar-coating process (see Figure). The promise of this low-cost polymeric device production technology is exemplified by the fabrication of MEH-PPV-based LEDs (see inside front cover).

    16. Novel Bisthienylethene-Based Photochromic Tetraazaporphyrin with Photoregulating Luminescence (pages 918–923)

      H. Tian, B. Chen, H.-Y. Tu and K. Müllen

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<918::AID-ADMA918>3.0.CO;2-Y

      A “hybrid photochromic” molecule with intertwined tetraazaporphyrin and bisthienylethene (BTE) chromophores is presented. The key photo-process is the simultaneous cyclization of two BTE units (yielding the molecule shown in the Figure) with high quantum yield at RT, and with a strongly temperature-dependent yield for the reverse reaction. The molecule is, thus, an ideal candidate for non- destructive readout optical memory devices.

    17. Fast Spectral Hole Burning in Sm2+-Doped Al2O3–SiO2 Glasses (pages 923–926)

      M. Nogami and K. Suzuki

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<923::AID-ADMA923>3.0.CO;2-D

      High-speed persistent spectral hole burning (PSHB), 30 times faster than in a similar H2 gas treated glass, has been achieved for a samarium(II)-doped alumina–silica glass upon irradiation with X-rays. Glasses of this type, enabling fast and highly efficient hole burning, are excellent candidates for binary high-density memory devices. Hole burning probably proceeds by a novel mechanism, i.e., the reaction of the X-ray irradiation-generated Sm2+ ions with oxygen ions to re-establish the original, stable trivalent oxidation state of samarium.

    18. Zeolitic Tissue Through Wood Cell Templating (pages 926–929)

      A. Dong, Y. Wang, Y. Tang, N. Ren, Y. Zhang, Y. Yue and Z. Gao

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<926::AID-ADMA926>3.0.CO;2-1

      Zeolitic wood structures made by a seeded templating process offer new ways of investigating the complex wood morphology. The technique can also be used to create hierarchical porous zeolitic materials (see Figure). The seeded growth strategy shows potential for the extension to any organisms with hierarchical structure and might make multilevel porous zeolites of other types feasible.

    19. Single Route for Producing Organized Metallic Domes, Dots, and Pores by Colloidal Templating and Over-Sputtering (pages 930–933)

      Mikrajuddin, F. Iskandar and K. Okuyama

      Article first published online: 17 JUN 2002 | DOI: 10.1002/1521-4095(20020618)14:12<930::AID-ADMA930>3.0.CO;2-L

      Ordered arrays of metallic domes, dots, and pores can be produced by exploiting a combination of colloidal templating and “over sputtering”. This elegant method involves deposition of metal onto a layer of polystyrene latex beads. The beads are then removed by heating to leave dome-shaped metal “shells” (see Figure). Upon further heating the domes can be converted to metallic dots. Pores are obtained if colloidal multilayers are used.

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