Advanced Materials

Cover image for Vol. 15 Issue 4

February, 2003

Volume 15, Issue 4

Pages 265–336

    1. Contents: Adv. Mater. 4/2003 (pages 265–268)

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390064

    2. Electron Energetics at Surfaces and Interfaces: Concepts and Experiments (pages 271–277)

      D. Cahen and A. Kahn

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390065

      Basic notions related to the electron energetics of solid surfaces and interfaces are discussed. Use of molecules for and in electronics requires knowledge of how the electronic energy levels of the molecules match and change those of the other components they are combined with. This didactic review, which also describes standard techniques used to measure such quantities, pulls together the different views and terminologies used in the solid state, surface science, electrochemistry, and electronic device communities. In this way one can then put key concepts, such as the so-called local and absolute vacuum levels, as well as work function, electron affinity, and ionization energy, and including surface dipole effects, on a common scale.

    3. Artificial Muscles with Tactile Sensitivity (pages 279–282)

      T.F. Otero and M.T. Cortés

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390066

      All-polymeric triple-layer artificial muscles capable of pushing obstacles that they meet during their angular movement are presented (see Figure). Upon contact of the muscle with an obstacle, a potential step proportional to the weight of the object evolves. Thus the muscle works simultaneously as an actuator and a tactile sensor.

    4. Cholesteric Mixtures with Photochemically Tunable, Circularly Polarized Fluorescence (pages 282–287)

      A.Yu. Bobrovsky, N.I. Boiko, V.P. Shibaev and J.H. Wendorff

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390067

      Photo-patternable cholesteric materials that combine fluorescence and a photochemically variable helical pitch have been investigated. Two cholesteric mixtures containing chiral photochromic (see Figure) as well as fluorescent dopants are examined. It is shown that photoregulation of both the fluorescence intensity and the polarization state of the emitted light can be realized.

    5. Long-Lived Photoinduced Charge Separation in (Zinc, Lead) Phosphate Glass–C60 Composites (pages 287–290)

      R. Sahoo and R. Debnath

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390068

      A group of (zinc, lead) phosphate glass–C60 composites that display long-lived photoinduced electron transfer from the Pb2+ center to the fullerene upon 230–400 nm UV irradiation has been developed. Both the steady state photoinduced absorption and photoinduced electron spin resonance spectra of the irradiated system support this view. Analysis of the carrier dynamics suggests that the electrons migrate from the hole sites to the fullerene sites in a tunneling mode.

    6. Patterning of Polypeptide Thin Films by the Combination of Surface-Initiated Vapor-Deposition Polymerization and Photolithography (pages 290–293)

      Y. Wang and Y.C. Chang

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390069

      A solvent-free strategy offering a fast, economical, and clean approach to integrate polypeptide materials into micrometer-scale devices is presented. The dimensions and compositions can be controlled in both the lateral and vertical directions. The Figure shows a surface-grafted pattern composed of PMLG (poly(γ-methyl-L-glutamate)) and PMLG-b-PBLG, (B indicates benzyl instead of methyl).

    7. A New Soluble 1,10-Phenanthroline-Containing π-Conjugated Polymer: Synthesis and Effect of Metal Complexation on Optical Properties (pages 293–296)

      T. Yasuda, I. Yamaguchi and T. Yamamoto

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390070

      A new 1,10-phenanthroline-containing π-conjugated polymer, the color of which can be tuned from blue to red by metal complexation, has been synthesized. The polymer responds sensitively to various metal ions due to its high coordinating ability, and the Figure shows emission from the polymer–metal complexes under 365 nm irradiation. The complexes are expected to serve as materials for light-emitting diodes.

    8. Spontaneous Vertical Ordering and Pyrolytic Formation of Nanoscopic Ceramic Patterns from Poly(styrene-b-ferrocenylsilane) (pages 297–300)

      K. Temple, K. Kulbaba, K.N. Power-Billard, I. Manners, K.A. Leach, T. Xu, T.P. Russell and C.J. Hawker

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390071

      The rapid generation of nanopatterned surfaces using thin films of the amorphous diblock copolymer poly(styrene-b-ferrocenylethylmethylsilane) (PS-b-PFS) is reported. Spontaneous self-assembly into vertically oriented cylinders of PFS in a PS matrix is observed on a variety of substrates by spin or dip coating, irrespective of the substrate surface polarity. Pyrolysis of the films affords arrays of 20 nm Fe-containing ceramic nanoparticles, (see Figure, AFM, 4 μm2 scan area).

    9. Laser Pruning of Carbon Nanotubes as a Route to Static and Movable Structures (pages 300–303)

      K.Y. Lim, C.H. Sow, J. Lin, F.C. Cheong, Z.X. Shen, J.T.L. Thong, K.C. Chin and A.T.S. Wee

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390072

      A simple focused laser beam pruning method is used to fabricate unique two- and three- dimensional structures (see Figure and the cover), without a pre-patterned substrate and under ambient conditions. The construction of microscopic movable carbon nanotube (CNT) structures that are controlled by laser light are also reported. The technique allows a wide range of 3D CNT microstructures to be created.

    10. A Novel Method for Preparing Copper Nanorods and Nanowires (pages 303–305)

      Z. Liu and Y. Bando

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390073

      Vacuum vapor deposition of copper nanorods and nanowires (see Figure) is reported. This novel one-step procedure involves copper vapor generation and redeposition on a substrate under very low pressure or vacuum conditions. Nanorods and nanowires of a variety of materials apart from copper, e.g., other metals, alloys, and semiconductors, can also be synthesized using this method.

    11. Field-Effect Transistors Based on Oligothienylenevinylenes: From Solution π-Dimers to High-Mobility Organic Semiconductors (pages 306–310)

      C. Videlot, J. Ackermann, P. Blanchard, J.-M. Raimundo, P. Frère, M. Allain, R. de Bettignies, E. Levillain and J. Roncali

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390074

      The substitution pattern of oligothienylenevinylenes (see Figure) exerts a determining effect on the packing arrangement of individual oligomers in the solid state, and thus on field-effect mobility. These two parameters are tightly correlated to the propensity of the corresponding cation radical to dimerize in solution. The analysis of the π-dimerization of conjugated cation radicals in solution could be used to screen new candidates for devices.

    12. A Conducting Polymer Artificial Muscle with 12 % Linear Strain (pages 310–313)

      L. Bay, K. West, P. Sommer-Larsen, S. Skaarup and M. Benslimane

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390075

      A soft polymer actuator has been constructed based on the volume change of a conducting polymer. The linear expansion (12 % at a load of 0.5 MPa) is the highest yet reported for a centimeter-scale conducting polymer actuator. This is achieved by controlling the structure on several length scales: Choice of molecular structure, synthesis from a structured medium, and forming the polymer actuator on a compliant, microstructured gold electrode.

    13. Dendrimer-Based Hydroxyapatite Composites with Remarkable Materials Properties (pages 313–316)

      J.J.J.M. Donners, R.J.M. Nolte and N.A.J.M. Sommerdijk

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390076

      The biomimetic formation of hydroxyapatite composites using complexes of alkylated dendrimers (see Figure) and surfactants as templates is described. Despite a high organic content, high stiffness is displayed, and for one dendrimer/surfactant combination investigated, significant toughening is observed.

    14. Supercritical Fluid Fabrication of Metal Nanowires and Nanorods Templated by Multiwalled Carbon Nanotubes (pages 316–319)

      X.-R. Ye, Y. Lin, C. Wang and C.M. Wai

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390077

      Metal nanorods and nanowires (see Figure) have been synthesized using multiwalled carbon nanotubes (MWCNTs) as templates and supercritical CO2 as the reaction medium. This rapid, direct, and clean approach can also be used to fabricate other metal/CNT composites and to coat the CNTs with metal films or nanoparticles.

    15. High-Energy Photonic Bandgap in Sb2S3 Inverse Opals by Sulfidation Processing (pages 319–323)

      B.H. Juárez, M. Ibisate, J.M. Palacios and C. López

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390078

      Large Sb2S3 inverse opals have been prepared that show extraordinary photonic behavior. A wide and well-defined peak in the reflectance spectrum in the range 700–800 nm defines the most energetic full photonic bandgap in the literature. The homogeneity (see Figure) and degree of infiltration of the samples improve on those prepared by CBD methods.

    16. Hydrogen-Assisted Thermal Evaporation Synthesis of ZnS Nanoribbons on a Large Scale (pages 323–327)

      Y. Jiang, X.-M. Meng, J. Liu, Z.-Y. Xie, C.-S. Lee and S.-T. Lee

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390079

      Semiconductor nanoribbons of ZnS have been synthesized on a large scale via hydrogen-assisted thermal evaporation. The product is characterized by means of electron microscopy and energy-dispersive X-ray spectroscopy, which show that the as-prepared ZnS nanoribbons are single crystals with uniform morphology. A stable and strong emission band centered at 534.5 nm is also associated with the nanoribbons.

    17. Laser-Writable, Electrically Erasable Photoelectrochromic Organic Film (pages 327–329)

      M. Macchione, G. De Filpo, A. Mashin, F.P. Nicoletta and G. Chidichimo

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390080

      An organic photoelectrochromic film, in which methylene blue can change from blue to transparent on absorption of light, and return to blue by an oxidation reaction induced by an external electric field, is presented (see Figure). The resulting device presents the remarkable advantage of being driven by a red HeNe laser (5 mW) for the “writing process”, and by a very low voltage (0.4 V) for the “erasing process”.

    18. Divanadium Pentoxide Nanorods (pages 329–331)

      N. Pinna, U. Wild, J. Urban and R. Schlögl

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390081

      The reverse micelle technique, here used to synthesize divanadium pentoxide nanorods, enables the nanorod length to be tuned easily by simply keeping them in the micellar solution after the synthesis. The nanorods are characterized by transmission electron microscopy, X-ray photoemission spectroscopy, and X-ray diffraction. These techniques show that the nanorods are made of divanadium pentoxide with the structure of γ-V2O5.

    19. Selective Dewetting for General Purpose Patterning (pages 332–334)

      Y.S. Kim and H.H. Lee

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390082

      General purpose patterning based on selective dewetting with an elastomeric mold is described. Several well-defined nanostructures obtained by this method are presented (see Figure for an example). Unlike other patterning techniques, the same mold can be used to generate features ranging in size from the nanometer to the micrometer, simply by changing the duration of dewetting.

    20. Author Index and Subject Index Adv. Mater. 4/2003 (page 336)

      Article first published online: 27 FEB 2003 | DOI: 10.1002/adma.200390083