Advanced Functional Materials

Cover image for Vol. 13 Issue 6

June, 2003

Volume 13, Issue 6

Pages 423–502

    1. Novel Chromogenic Esters of ortho-Phenylazonaphthols (pages 427–433)

      C. Kocher, C. Weder and P. Smith

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304280

      Photo- and acid-labile derivatives of ortho-phenylazonaphthol dyes are “locked” in an azo configuration and exhibit > 100 nm blue-shifted absorbance spectra with strongly reduced extinction coefficients compared to their parent chromophores. Polymer films of these novel chromogenic dyes can be patterned by masked irradiation (see Figure), and they are potentially suitable for marking goods, optical data storage, and sensing applications.

    2. Layer-Structured Photoconducting Polymers: A New Class of Photorefractive Materials (pages 434–438)

      O-P. Kwon, S.-H. Lee, G. Montemezzani and P. Günter

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304302

      The interesting photorefractive properties of side group polymer systems based on a rigid backbone of poly(p-phenyleneterephthalate) with layered structures are reported. Despite the absence of a plasticizer and the lower concentration of the carbazole groups as compared to poly(N-vinylcarbazole) systems, these materials show excellent photorefractive properties.

    3. Electrophosphorescence from a Polymer Guest–Host System with an Iridium Complex as Guest: Förster Energy Transfer and Charge Trapping (pages 439–444)

      X. Gong, J.C. Ostrowski, D. Moses, G.C. Bazan and A.J. Heeger

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304334

      Green electrophosphorescent light-emitting diodes (LEDs) with a luminance of 3500 cd m–2 were fabricated from a PVK–PBD (poly(vinylcarbazole)–2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol) polymer blend doped with an iridium complex. The devices exhibited an external quantum efficiency of 8 % ph/el and a luminous efficiency of 29 cd A–1. The results demonstrate that Förster energy transfer plays a minor role in achieving high efficiencies in these devices; direct charge trapping appears to be the main operating mechanism. (See also cover)

    4. High-Tg Carbazole Derivatives as Blue-Emitting Hole-Transporting Materials for Electroluminescent Devices (pages 445–452)

      P. Kundu, K.R. Justin Thomas, J.T. Lin, Y.-T. Tao and C.-H. Chien

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304308

      Aromatic bridged biscarbazolyl derivatives containing peripheral diarylamine segments (see Figure) have been synthesized and successfully fabricated into organic LEDs as emitting hole-transporting materials. Their Tg is dependent on the bridging aromatic unit and the peripheral diarylamine segments. The molecules’ effective hole-transporting properties are attributed to the multiple hopping pathways provided by the peripheral diarylamine moieties.

    5. Ultra-Low-Loss Acrylate Polymers for Planar Light Circuits (pages 453–462)

      L.W. Shacklette, R. Blomquist, J.M. Deng, P.M. Ferm, M. Maxfield, J. Mato and H. Zou

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304266

      Waveguides exhibiting ultra-low optical loss at telecommunication wavelengths have been fabricate from liquid multifunctional perfluoroakyl and perfluoroalkylether acrylate macromonomers (see Figure). These materials enable devices with significantly reduced polarization dependence and improved thermal response needed for the performance of thermo-optic devices.

    6. Size-Specific Interactions Between Single- and Double-Stranded Oligonucleotides and Cationic Water-Soluble Oligofluorenes (pages 463–467)

      S. Wang, B. Liu, B.S. Gaylord and G.C. Bazan

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304339

      An improved synthetic approach has been developed for the synthesis of well-defined water-soluble oligofluorenes 1ac (see Figure). They provide a size-specific sequence of oligofluorene molecules with an increasing number of repeat units with which to model the interactions between cationic conjugated polymers and DNA (see cover).

    7. From Hybrid Microgels to Photonic Crystals (pages 468–472)

      S. Xu, J. Zhang, C. Paquet, Y. Lin and E. Kumacheva

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304338

      Semiconductor and metal nanoparticles (NPs) have been synthesized in the interior of polymer microgels. Good control over the NP size and concentration can be achieved by changing the polymer composition. Doped microgel particles (see Figure) can be encapsulated with a hydrophobic polymeric shell and used as the building blocks of a nanostructured material that has the properties of a photonic crystal.

    8. Electroactivity of Polyaniline Multilayer Films in Neutral Solution and Their Electrocatalyzed Oxidation of β-Nicotinamide Adenine Dinucleotide (pages 473–479)

      S. Tian, A. Baba, J. Liu, Z. Wang, W. Knoll, M.-K. Park and R. Advincula

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304320

      Polyaniline (PANI) multilayer films, self-assembled with a series of polyanions by the layer-by-layer (LBL) method, show very good stability, reversibility, and electroactivity in neutral solutions. All the films can electrocatalyze the oxidation of β-nicotinamide adenine dinucleotide (NADH) (see Figure), although their catalytic efficiencies are different. Such electroactive PANI multilayers show great potential for thin film devices and biosensor applications.

    9. The Transient Phase of Amorphous Calcium Carbonate in Sea Urchin Larval Spicules: The Involvement of Proteins and Magnesium Ions in Its Formation and Stabilization (pages 480–486)

      S. Raz, P.C. Hamilton, F.H. Wilt, S. Weiner and L. Addadi

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304285

      Sea urchin larvae produce spicules that are mainly composed of amorphous calcium carbonate (ACC), which transforms into a single crystal of calcite. This transient ACC phase differs both in structure and composition from the known stable ACC phases. The macromolecules extracted from immature spicules transiently stabilize ACC in vitro in the presence of Mg ions, while macromolecules extracted from mature spicules do not. The Figure shows a Strongylocentrotus purpuratus embryo 72 h after fertilization.

    10. Sulfur Composite Cathode Materials for Rechargeable Lithium Batteries (pages 487–492)

      J. Wang, J. Yang, C. Wan, K. Du, J. Xie and N. Xu

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304284

      Conductive-polymer/sulfur composites are reported as potential cathode materials for rechargeable lithium batteries due to their structure, i.e., sulfur embedded in a conductive polymer host at a molecular level (see Figure for a TEM image). The low-cost, environmentally friendly sulfur composite has outstanding electrochemical properties and is a highly promising material for the next generation of lithium batteries.

    11. Laser-Ablation Growth and Optical Properties of Wide and Long Single-Crystal SnO2 Ribbons (pages 493–496)

      J.Q. Hu, Y. Bando, Q.L. Liu and D. Golberg

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304327

      Wide and long ribbons of single-crystalline SnO2 have been synthesized via laser ablation of a SnO2 target. The as-grown ribbons are structurally uniform single crystals that grow along the [100] direction, and have widths of 300–500 nm, thicknesses of 30–50 nm (width-to-thickness ratio of ∼ 10), and lengths ranging from several hundreds of micrometers to the order of millimeters (see Figure).

    12. Metastable Hexagonal In2O3 Nanofibers Templated from InOOH Nanofibers under Ambient Pressure (pages 497–501)

      D. Yu, S.-H. Yu, S. Zhang, J. Zuo, D. Wang and Y.T. Qian

      Version of Record online: 5 JUN 2003 | DOI: 10.1002/adfm.200304303

      Single crystal metastable hexagonal In2O3 nanofibers with an average diameter of 80 nm and lengths of up to several micrometers (see Figure) can be easily synthesized in large scale under ambient pressure by annealing InOOH nanofibers at 490 °C, which were in turn prepared by a controlled hydrolysis solvothermal reaction using InCl3·4H2O as starting material and ether as solvent at 190–240 °C.