Advanced Functional Materials

Cover image for Vol. 11 Issue 5

October, 2001

Volume 11, Issue 5

Pages 323–397

    1. Magnetic Fluids: Fabrication, Magnetic Properties, and Organization of Nanocrystals (pages 323–336)

      M.-P. Pileni

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<323::AID-ADFM323>3.0.CO;2-J

      Ferrite and cobalt magnetic fluids are organized in 3D superlattices to form various mesoscopic structures (the Figure shows an SEM image of a structure on HOPG, showing the hexagonal arrangement), as is revealed in this article. Different ways to make magnetic fluids from colloidal self-assemblies are described and the magnetic properties of these fluids, as well as the properties of ferrite and cobalt nanocrystals, are determined and illustrated.

    2. Tailor-made Structuring of Zeolite Matter (pages 337–338)

      J. A. Martens and P. A. Jacobs

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<337::AID-ADFM337>3.0.CO;2-#

      Novel zeolite synthesis approaches are leading to new insights into the molecular mechanisms of zeolite nucleation and growth. This article highlights some of the latest results on heteroepitaxial growth in the effort to achieve tailor-made structuring of zeolite matter. The main focus of the article lies in a very recent report on the overgrowth of millimeter-sized sodalite with cancrinite crystals (see Figure).

    3. High Performance Polymer Light-Emitting Diodes Fabricated by a Low Temperature Lamination Process (pages 339–343)

      T.-F. Guo, S. Pyo, S.-C. Chang and Y. Yang

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<339::AID-ADFM339>3.0.CO;2-S

      A new process for the fabrication of polymer light-emitting diodes (LEDs) is unveiled. The anode and cathode part of the device are independently produced by a template activated surface (TAS) process and are laminated together to form the final device. This process and the final properties of the devices are described and thoroughly discussed. The Figure shows a 2 × 3 light-emitting device.

    4. Synthesis of Metal Nanoparticles via Self-Regulated Reduction by an Alcohol Surfactant (pages 344–347)

      C.-L. Lee, C.-C. Wan and Y.-Y. Wang

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<344::AID-ADFM344>3.0.CO;2-7

      Alcohol surfactants act as both protective agents and reductants in the method developed by these authors for the synthesis of noble metal nanoparticles. It is shown that the diameter of the nanoparticles can be controlled by changing the length of the surfactant carbon chain and, as illustrated in the Figure, 3D “spheres–around–sphere” type nanostructures form under the right conditions.

    5. Microtribology and Friction-Induced Material Transfer in WS2 Nanoparticle Additives (pages 348–354)

      C. Drummond, N. Alcantar, J. Israelachvili, R. Tenne and Y. Golan

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<348::AID-ADFM348>3.0.CO;2-S

      The unique tribological behavior of tungsten disulfide (WS2) has been studied with a myriad of experimental techniques and the results are reported here. Ordered, ultrathin layers (see Figure) are observed when nested particles are sheared, whilst WS2 platelets produce a rough and disordered layer with inferior lubricating properties.

    6. Unusually Fast Optically Induced Birefringence in Polyoxetanes Bearing 4-(N,N-Diphenyl)amino-4′-nitroazobenzene Chromophores (pages 355–360)

      S. W. Cha, D. H. Choi and J.-I. Jin

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<355::AID-ADFM355>3.0.CO;2-#

      Azobenzene chromophore–containing polymers are of interest for applications in nonlinear optics and holography. The preparation, photoinduced molecular orientation, and relaxation of two novel polyoxetane polymers are reported and compared. It is found that different modes of attachment of the chromophores—either “side on” (see Figure) or “end on”—lead to different maximum birefringence and (fast) photoresponse rates.

    7. Synthesis and Properties of Designed Low-k Fluoro-Copolyetherimides. Part 1 (pages 361–373)

      R. H. Vora, P. S. G. Krishnan, S. H. Goh and T.-S. Chung

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<361::AID-ADFM361>3.0.CO;2-B

      Polyetherimides (PEIs) are versatile melt-processable resins applicable in microelectronics as low-dielectric-constant materials. Several fluoro-PEIs—e.g., 6FDA + BDAF (see Figure)—were designed on paper and their theoretical dielectric constants compared with experimental values. Amorphous PEIs bearing bis-CF3 groups showed the desired properties.

    8. Origin of the Open Circuit Voltage of Plastic Solar Cells (pages 374–380)

      C. J. Brabec, A. Cravino, D. Meissner, N. S. Sariciftci, T. Fromherz, M. T. Rispens, L. Sanchez and J. C. Hummelen

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<374::AID-ADFM374>3.0.CO;2-W

      A variation of almost 200 mV has been found for the first reduction potential of a series of highly soluble fullerene derivatives with varying acceptor strengths that were used as electron acceptors in plastic solar cells. This observation, which also relates the open circuit voltage to the acceptor strengths, is discussed within the concept of Fermi level pinning between fullerenes and metals. The Figure shows an azafulleroid that was used in this investigation.

    9. Self-Alignment of Patterned Wafers Using Capillary Forces at a Water–Air Interface (pages 381–386)

      B. R. Martin, D. C. Furnange, T. N. Jackson, T. E. Mallouk and T. S. Mayer

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<381::AID-ADFM381>3.0.CO;2-3

      Capillary interactions at a water–air interface can be used to align a two-inch glass wafer to a three-inch silicon wafer. The accuracy of this alignment is better than one micrometer and gravitational energy has been used to systematically study the alignment force as a function of pattern parameters. The Figure shows the misalignment of two wafers by 2 μm in the x-direction and 3 μm in the y-direction.

    10. Electrochemical Properties of High-Power Supercapacitors Using Single-Walled Carbon Nanotube Electrodes (pages 387–392)

      K. H. An, W. S. Kim, Y. S. Park, J.-M. Moon, D. J. Bae, S. C. Lim, Y. S. Lee and Y. H. Lee

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<387::AID-ADFM387>3.0.CO;2-G

      Supercapacitors constructed using single-walled carbon nanotube electrodes (SWNTs): What are the key factors determining their performance? This question is answered and several parameters—e.g., composition of binder, annealing temperature, charging time—optimized with respect to energy and power density are presented. The Figure is a field-emission SEM image of as-grown SWNTs, showing entanglements and crosslinking.

    11. Nanoscale Refractive Index Tuning of Siloxane-Based Self-Assembled Electro-Optic Superlattices (pages 393–397)

      M. E. van der Boom, G. Evmenenko, P. Dutta and T. J. Marks

      Version of Record online: 2 OCT 2001 | DOI: 10.1002/1616-3028(200110)11:5<393::AID-ADFM393>3.0.CO;2-S

      An efficient approach to the assembly of organic–inorganic hybrid electro-optic (EO) superlattices, having refractive indices tunable over a significant and useful range, is demonstrated. This solution-based deposition of high-Z metal oxide layers is suitable for nanometer scale film construction with vertical organization of the microstructure and represents a new approach to metal- dependent modification of superlattice physicochemical properties. Importantly, no specially designed ligand systems of metal ion scaffolds are necessary.