Solid State Phenomena Vols. 121-123

Abstract: In this work, we have investigated phase separation behavior in PS/PVP polymer blend thin films on gold substrates that have chemical stripes of different periods made by microcontact printing. The influences of pattern period and film thickness have been studied. The experiments have testified that the best result of phase separation, as shown in OM image, was obtained when the period of the chemical pattern is similar to the polymer particle size. Meanwhile, the film thickness plays a significant role on the phase separation. The best pattern replication in the polymer thin films only occurs in a relative narrow thickness range, for example, in this case between 30 and 60 nm. The possible interaction mechanism of the thin polymer film with the underlayed chemical pattern has been discussed.

Abstract: A family of mesoporous multilamellar silica vesicles has been successfully synthesized by using P123 as structure directing agent and hexane as co-surfactant. The structure was characterized with XRD, TEM, and N2 adsorption-desorption isotherms. This multilamellar silica vesicle materials process high specific area, large pore volume, and a bimodale pore size distribution. Furthermore, these materials are stable when the surfactant is removed at 530 oC.

Abstract: Copper(0) nanoparticles in nanoporous nickel phosphate VSB-1 were prepared by the methods of ion exchange and hydrogen reduction. X-ray powder diffraction (XRD) results show that the crystal structure of VSB-1 was well retained after the encapsulation of copper nanoparticles and no apparent evidence of crystalline copper was observed. The Cu 2p core level binding energies were consistent with elemental Cu(0) appear in the X-ray photoelectron spectroscopy (XPS) data. Room temperature ultra violet visible (UV-Vis) absorption spectrum is characteristic of Cu(0) nanoparticles [1, 2]. Nanoporous material VSB-1 is an excellent host to synthesize metal or metal oxide nanoparticles due to its homogeneous nanopores and its high thermal stability.

Abstract: Site-selective growth of multi-walled carbon nanotubes (MWCNTs) from an iron oxide nanoparticle catalyst patterned by drying-mediated self-assembly technique is present. The ethanol solution of the iron nitrate was employed as catalyst precursor. The catalyst precursor was mounted on silicon wafer by dip-coating. After evaporation of solvent at room temperature, the catalyst pattern formed. The catalyst pattern was employed to synthesize carbon nanotube pattern by chemical vapor deposition of ethanol vapor after oxidation of iron nitrate. The patterned array of MWCNTs was obtained with a dot size of around 5 'm and the distance of about 25 'm. The present method offers a simple and cost-effective method to grow carbon nanotubes with self-assembled patterns.

Abstract: We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

Abstract: An assessment is made of the suitability of the carbon nanotube field-effect transistor for applications in nanoelectronics.

Abstract: Fabrication of flexible device structures and nanoscale size definition are presently among the most important and ambitious development goals in the IT field. We have recently prepared the vertical nanowire field effect transistor in the flexible polymer foils based on ion tracks. The high-energetic fast heavy ions were used to irradiate the 8μm PET foils and then the chemical etching method were employed to prepare cylindrical channels in these PET foils. These channels were subsequently filled with insulator material and semiconductor, and then provided with suitable metallic contacts, to obtain a vertical field-effect transistor device. Preparation and first electronic results on this new device are reported. Typically over 107 transistors per cm2 with the devices’ diameter of ~100 nm can be obtained in this technique. The fabrication does not require lithography on the scale of a single transistor, and is suitable for large-area and flexible applications.