Advanced Materials

Cover image for Vol. 14 Issue 17

September, 2002

Volume 14, Issue 17

Pages 1177–1247

    1. Contents: Adv. Mater. 17/2002 (pages 1177–1181)

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1177::AID-ADMA1177>3.0.CO;2-Z

    2. Contents: Chem. Vap. Deposition 5/2002 (pages 1183–1184)

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1183::AID-ADMA1183>3.0.CO;2-K

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      Interview: In Profile: Jürg Hullinger (page 1185)

      Article first published online: 3 SEP 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1185::AID-ADMA1185>3.0.CO;2-8

    4. Non-lithographic Approach to the Fabrication of Polymeric Nanostructures with a Close-Packed 2D Hexagonal Array (pages 1187–1190)

      W. Lee and J.-K. Lee

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1187::AID-ADMA1187>3.0.CO;2-X

      A simple and completely non-lithographic route to free-standing nanostructured polymeric films with a close-packed hexagonal array of nanoembossments or nanorods is presented in which electrochemically prepared textured aluminum sheets or nanoporous anodic alumimum oxide are used. The Figure shows an polystyrene/PMMA nanoparticle composite.

    5. Silicon Chip for Electronic Communication Between Nerve Cells by Non-invasive Interfacing and Analog–Digital Processing (pages 1190–1193)

      P. Bonifazi and P. Fromherz

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1190::AID-ADMA1190>3.0.CO;2-#

      Direct communication between two disconnected nerve cells via a semiconductor chip with integrated circuitry has been achieved (see Figure), enabling reliable feeding of single action potentials from nerve cells into a digital electronic processor. The intrinsic problem of stimulation/recording crosstalk is also addressed. This system represents a key step towards neurocomputing.

    6. (BEDT-TTF)2PF6 Thin Films—A New Approach to the Preparation of Films From Charge-Transfer Salts (pages 1193–1196)

      H.H. Wang, K.L. Stamm, J.P. Parakka and C.Y. Han

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1193::AID-ADMA1193>3.0.CO;2-I

      Densely covered (ET)X2 thin films (ET = bis-ethylenedithio-tetrathiafulvalene, X = counter-anion) can be formed by selective electrodeposition on gold electrodes (see Figure). The insulating (ET)X2 films are converted to (ET)2X conductive thin films through a novel conproportionation reaction. This procedure opens up the possibility to prepare patterned conductive and superconductive charge-transfer salt thin films.

    7. Supramolecular Route to Fluorinated Coatings: Self-Assembly Between Poly(4-vinylpyridines) and Haloperfluorocarbons (pages 1197–1201)

      R. Bertani, P. Metrangolo, A. Moiana, E. Perez, T. Pilati, G. Resnati, I. Rico-Lattes and A. Sassi

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1197::AID-ADMA1197>3.0.CO;2-V

      A simple supramolecular method for the direct self-assembly of comb-like complexes composed of hydrocarbon polymers and perfluorocarbon mesogens is described. Halogen bonding is highly directional, so that perfluoroalkyl residues with their rigid rod-like architecture result in materials with a beautiful comb-like structure. The Figure shows an ORTEP view of such co-crystals.

    8. Active-Matrix Displays Driven by Solution-Processed Polymeric Transistors (pages 1201–1204)

      H.E.A. Huitema, G.H. Gelinck, J.B.P.H. van der Putten, K.E. Kuijk, C.M. Hart, E. Cantatore and D.M. de Leeuw

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1201::AID-ADMA1201>3.0.CO;2-5

      An active-matrix display, refreshable at video speed, based on a solution-processed organic semiconductor (the principle underlying low-cost electronic paper) is presented. The combination of a sufficient on-current, a very low off-current, and a high uniformity allows display images with 256 gray levels, while using line-by line addressing. The Figure shows a 65 × 65 display driven by 4096 polymer thin film transistors (see also cover).

    9. Layer-by-Layer Grafting of Molecularly Imprinted Polymers via Iniferter Modified Supports (pages 1204–1208)

      B. Sellergren, B. Rückert and A.J. Hall

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1204::AID-ADMA1204>3.0.CO;2-O

      “Living” functional composite materials have been prepared by grafting of molecularly imprinted polymers (MIPs) from dithiocarbamate-modified porous silica supports (see Figure). The living properties of the system are demonstrated by consecutive grafting of two polymer layers imprinted with chiral templates. The enantioselectivity of the first layer is reversed by grafting a second layer imprinted with the antipode.

    10. Trititanate Nanotubes Made via a Single Alkali Treatment (pages 1208–1211)

      Q. Chen, W. Zhou, G.H. Du and L.-M. Peng

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1208::AID-ADMA1208>3.0.CO;2-0

      A new type of crystalline trititanate nanotube (see Figure and inside front cover for a 3D drawing) has been synthesized in a single alkali treatment. Novel formation mechanisms of the nanotubes are proposed based on a series of experiments. In the process, NaOH can be regarded as a catalyst and a reusable source. The synthetic method is extremely inexpensive and may be applied to synthesize other oxide nanostructures.

    11. Photostable and Strongly Fluorescent Materials (pages 1211–1213)

      Y. Matsubara, T. Matsuda, S. Hatta, Y. Yamaguchi and Z. Yoshida

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1211::AID-ADMA1211>3.0.CO;2-3

      Photostable and strongly fluorescent pyrazolines have been prepared by introduction of various substituents into the pyrazoline (see Figure) and phenyl rings. The fluoro-substituted derivative (R1 = R2 = R3 = F; R4 = CF3) is shown to be a state-of-the-art substance in terms of luminescent efficiency and photostability.

    12. Generation of Chrome Masks with Micrometer-Scale Features Using Microlens Lithography (pages 1213–1216)

      H. Wu, T.W. Odom and G.M. Whitesides

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1213::AID-ADMA1213>3.0.CO;2-S

      Periodic patterns with submicrometer features in a photoresist supported on glass have been generated using arrays of microlenses and macroscopic transparency-film photomasks. The Figure shows a pattern obtained with a mask in the shape of the letter “G”. Deposition of a chromium film, followed by lift-off, converts the photoresist pattern into a chrome mask for pattern transfer to other substrates by contact photolithography.

    13. Hydrothermal Synthesis of Single-Crystal Ni(OH)2 Nanorods in a Carbon-Coated Anodic Alumina Film (pages 1216–1219)

      K. Matsui, T. Kyotani and A. Tomita

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1216::AID-ADMA1216>3.0.CO;2-A

      The formation of Ni(OH)2 nanorods within an anodic oxide template via hydrothermal synthesis, followed by their subsequent liberation to form discrete NiO nanorods, is presented. The carbon can effectively be removed to form this uniform rod-like product. The Figure shows a schematic illustration of the synthesis.

    14. Silicon Nanotubes (pages 1219–1221)

      J. Sha, J. Niu, X. Ma, J. Xu, X. Zhang, Q. Yang and D. Yang

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1219::AID-ADMA1219>3.0.CO;2-T

      The preparation of silicon nanotubes (SiNTs) using nanochannel Al2O3 as a template and a chemical vapor deposition process is reported. The outer diameters of the SiNTs are around 60 nm with walls approximately 10 nm thick consisting of crystalline and amorphous silicon. A conceptual model is presented (see Figure) to account for the formation of SiNTs (right) as opposed to nanowires (left).

    15. Room-Temperature Lasing Observed from ZnO Nanocolumns Grown by Aqueous Solution Deposition (pages 1221–1224)

      K. Govender, D.S. Boyle, P. O’Brien, D. Binks, D. West and D. Coleman

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1221::AID-ADMA1221>3.0.CO;2-1

      White light luminescence and room-temperature lasing throughout the visible are demonstrated for ZnO nanocolumns grown on Au-coated tin-oxide glass. The directionality of the emission, the lasing threshold, and the observed mode spacing are all consistent with Fabry–Pérot lasing cavities. The Figure shows a cross-sectional SEM image of ZnO nanocolumns with an average nanocolumn length of ∼ 3 μm.

    16. Orientations of Liquid Crystals on Chemically Functionalized Surfaces That Possess Gradients in Nanometer-Scale Topography (pages 1224–1227)

      M.L. Tingey, Y.-Y. Luk and N.L. Abbott

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1224::AID-ADMA1224>3.0.CO;2-K

      Liquid crystal cells with gradients in nanometer-scale surface topography have been prepared by sandwiching two hexadecanethiol (C16) self-assembled monolayers between two gold films, one of which had been deposited at a fixed angle of incidence (40°), the other at an angle varied from 48° to 58° (see Figure for micrographs (length = 7 cm) under polarized light with crossed (top) and parallel (bottom) polars).

    17. Antimony Nanowire Arrays Fabricated by Pulsed Electrodeposition in Anodic Alumina Membranes (pages 1227–1230)

      Y. Zhang, G. Li, Y. Wu, B. Zhang, W. Song and L. Zhang

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1227::AID-ADMA1227>3.0.CO;2-2

      Highly ordered arrays of antimony nanowires have been fabricated reproducibly by pulsed electrodeposition in anodic alumina membranes. The nanowires are shown to be single crystalline, metallic, and have a diameter of 40 nm. The field emission microscopy image (see Figure) shows the degree of filling of the template and the variation in the height of the nanowires.

    18. Spin-Driven Resistance in Organic-Based Magnetic Semiconductor V[TCNE]x (pages 1230–1233)

      V.N. Prigodin, N.P. Raju, K.I. Pokhodnya, J.S. Miller and A.J. Epstein

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1230::AID-ADMA1230>3.0.CO;2-5

      The existence of spin polarized sub-bands, a half-semiconducting state in which the electron spins in “valence” and “conduction” bands are oppositely polarized, has been derived for the vanadium-organyl-based “soft” ferrimagnet V(TCNE)x by measurements of its electrical and magnetic resistance at different temperatures. The Figure shows a schematic of a level diagram for the system investigated.

    19. Cyclopalladated Complexes as Photorefractive Materials with High Refractive Index Modulation (pages 1233–1236)

      I. Aiello, D. Dattilo, M. Ghedini, A. Bruno, R. Termine and A. Golemme

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1233::AID-ADMA1233>3.0.CO;2-O

      A new class of multifunctional molecules for holographic applications is presented: the cyclopalladated complexes BEPON (see Figure) and AZPON rank among the best organic photorefractive materials known due to their excellent photoconductivity and field-induced refractive index modulation. Upon quenching from the melt, BEPON forms an amorphous composite in which the density of active molecules is very high.

    20. One-Step Replication Against a Thin-Layer Material Formed by Self-Assembly of Hollow Hemispheres on a Substrate (pages 1236–1238)

      I. Noda and M. Yamada

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1236::AID-ADMA1236>3.0.CO;2-6

      A choice of positive or negative replicas by micromolding is reported. Pressureless attachment of a mold consisting of self-assembled hollow hemispheres onto a polycarbonate (PC) fluid imprints the shape of the (air-filled) hemispheres into the PC as a positive replica (see Figure). Negative replicas can be formed by filling the mold consisting of thin-walled self-assembled hollow hemispheres with monomers, which are subsequently polymerized.

    21. Atom Transfer Radical Polymerization as a Tool for Surface Functionalization (pages 1239–1241)

      D. Bontempo, N. Tirelli, K. Feldman, G. Masci, V. Crescenzi and J.A. Hubbell

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1239::AID-ADMA1239>3.0.CO;2-P

      Atom transfer radical polymerization (ATRP) is receiving increasing attention as a method for surface functionalization. A simple way—based on the hydrophilicity of the substrate—to discriminate between surface and bulk polymerization in materials having a homogeneous distribution of initiator groups is discussed. The Figure shows an AFM image of polymer beads after functionalization in dimethylformamide.

    22. Creating “Smart” Surfaces Using Stimuli Responsive Polymers (pages 1243–1247)

      N. Nath and A. Chilkoti

      Article first published online: 29 AUG 2002 | DOI: 10.1002/1521-4095(20020903)14:17<1243::AID-ADMA1243>3.0.CO;2-M

      “Smart” surfaces that modulate their physico-chemical properties in response to environmental triggers can be fabricated by functionalization of a surface with stimuli-responsive polymers (SRPs). This article summarizes different approaches to the fabrication of “smart” surfaces and their applications. Recent results that demonstrate reversible micropatterning of proteins using a smart biopolymer as well as a simple, colorimetric assay to characterize the phase transition behavior of SRPs at the solid–water interface are highlighted.