Vaporization of (SN)x and TTF-TCNQ

The vaporization of (SN)x was studied by electron impact and chemical ionization mass spectrometry. Comparison of the spectra with those of S₄N₄ suggests that vaporization generates an unstable, acyclic S₄N₄ which subsequently fragments to a cyclic S₃N₃⁺ and SN⁺ ion in the mass spectrometer. Mass spectrometry may be used to analyze (SN)x for S₈ and cage S₄N₄. Vaporization of TTF-TCNQ produced the component donor and acceptor molecules.     

The preparation and characterization of crystals of the superconducting polymer, (SN)x

A technique is described for growing (SN)_x crystals which have superior electrical properties to those reported previously. The room temperature electrical conductivity has increased, so has the ratio of the room temperature and 4°K resistivities. There is no conductivity maximum in the region 20–30°K and the superconducting transition temperature is higher.     

Properties of inorganic polymer (geopolymer) mortars made of glass cullet

This study presents the results of experiments aiming to produce geopolymers from glass cullet, a non-traditional material compared to those usually found in the manufacture of geopolymers (e.g., metakaolin and fly ash). The study gives the principal formulation parameters affecting the behavior of glass cullet geopolymers. The glass used comes from recycled glass bottles. The parameters studied are the fineness of the glass (Blaine of 1000 to 4000 cm²/g), the temperature of synthesis (20, 40 and 60 °C), and the nature and concentration of the activation product (KOH, NaOH). The properties are evaluated in terms of compressive strength and durability. The results show that cullet of soda-glass can be used as a base material for the production of geopolymers and, contrary to metakaolin-based geopolymers, no waterglass is necessary for its setting and hardening since cullet glass already contains a high proportion of alkalis. Thermal activation at 40 or 60 °C is necessary but sufficient to obtain strength of more than 50 MPa, especially for the finer glass (4000 cm²/g). The durability of glass cullet geopolymers is affected by water conservation.     

Bond performance of reinforcing bars in inorganic polymer concrete (IPC)

The basic mechanical and chemical properties of fly-ash-based inorganic polymer concretes (IPC) have been studied widely, but, key engineering and structural properties of the material for instance modulus of elasticity, compressive, tensile, flexural strengths and bonding strength of the material to reinforcement have received little attention. Structural applications of reinforced IPC depend on the bond performance of the material to the reinforcement. Due to their difference with ordinary Portland cement (OPC) based concrete in terms of chemical reaction and matrix formation it is not known whether IPC exhibit different bonding performance with the reinforcement. Simply relying on compressive strength of the material and extrapolating models and equations meant for OPC based concrete may lead to unsafe design of structural members. To that end, 27 beam-end specimens, 58 cubic direct pullout type specimens and number of laboratory test specimens were tested to evaluate bonding performance of IPC with reinforcement. The results of beam-end specimens and direct pullout type specimens correlate favourably, although the results of direct pullout tests are in general more conservative than those of beam-end specimens. Overall, it can be concluded that bond performance of IPC mixes are comparable to OPC based concrete and therefore IPC and steel can be used as a composite material to resist tension in addition to compression.     

Optimization of the thermoelectric figure of merit in the conducting polymer poly(3,4-ethylenedioxythiophene)

Thermoelectric generators (TEGs) transform a heat flow into electricity. Thermoelectric materials are being investigated for electricity production from waste heat (co-generation) and natural heat sources. For temperatures below 200 °C, the best commercially available inorganic semiconductors are bismuth telluride (Bi(2)Te(3))-based alloys, which possess a figure of merit ZT close to one. Most of the recently discovered thermoelectric materials with ZT>2 exhibit one common property, namely their low lattice thermal conductivities. Nevertheless, a high ZT value is not enough to create a viable technology platform for energy harvesting. To generate electricity from large volumes of warm fluids, heat exchangers must be functionalized with TEGs. This requires thermoelectric materials that are readily synthesized, air stable, environmentally friendly and solution processable to create patterns on large areas. Here we show that conducting polymers might be capable of meeting these demands. The accurate control of the oxidation level in poly(3,4-ethylenedioxythiophene) (PEDOT) combined with its low intrinsic thermal conductivity (λ=0.37 W m(-1) K(-1)) yields a ZT=0.25 at room temperature that approaches the values required for efficient devices.     

The possibility of improving the structural perfection of the new heterojunctions GaAs-(Ge2)1− x (ZnSe)x, Ge-(Ge2)1−x (ZnSe)x, GaP-(Ge2)1−x (ZnSe)x, and Si-(Ge2)1−x (ZnSe)x

Based on morphological investigations, as well as on a study of the scanning patterns and diffraction spectra of the heterostructures GaAs-(Ge₂)_1−x (ZnSe)_x, Ge-(Ge₂)_1−x (ZnSe)_x, GaP-(Ge₂)_1−x (ZnSe)_x, and Si-(Ge₂)_1−x (ZnSe)_x, it is shown that the crystal perfection of these structures depends on the choice of the conditions of liquid-phase epitaxy. It is shown that mirror-smooth epitaxial layers of (Ge ₂)_1−x (ZnSe)_x with the lowest stress levels can be obtained on GaAs (100) and Ge (111) substrates. Pis’ma Zh. Tekh. Fiz. 24, 12–16 (January 26, 1998)     

Preparation of La2-x Sr x NiO4 (x = 0-1.3) conducting oxides via a citrate route

La_2-x Sr_xNiO₄ (x = 0-1.3) oxide materials were prepared by the citrate and ceramic routes. The citrate precursors and final products were characterized by thermal analysis (DTA + TG), x-ray diffraction, scanning electron microscopy, IR spectroscopy, and specific surface and conductivity measurements. The use of citrate mixtures leads to the formation of amorphous precursors to La₂O₃, NiO, and La_2-xSr_xNiO₄ (x <-0.4); reduces the temperature required for obtaining solid solutions by 150–200‡C as compared to the ceramic route; and enables the preparation of fine powders (≤5 Μm) and dense ceramics. Deceased.     

Flash welding of conducting polymer nanofibres

The absorption of light by a material generates heat through non-radiative energy dissipation and exothermic photochemical reactions. In nanostructured materials, the heat generated through photothermal processes will be confined within the individual nanostructures when heat transfer to neighbouring nanostructures and the environment is slow. This leads to unprecedented photothermal effects that cannot be observed in bulk materials, especially when a strong, pulsed light source is used. Here we demonstrate an enhanced photothermal phenomenon with conducting polymer nanofibres in which a camera flash causes instantaneous welding. Under flash irradiation, polyaniline nanofibres 'melt' to form a smooth and continuous film from an originally random network of nanofibres. This photothermal effect can be used to form asymmetric nanofibre films, to melt-blend polymer-polymer nanocomposites rapidly and to photo-pattern polymer nanofibre films.     

可溶性导电高分子的合成方法

导电高分子在电子和光电子领域具有广泛的用途。可通过合成可溶性前驱体 ,引入侧基 ,使通用高分子和导电高分子的复合化的方法来提高导电高分子的可溶性     

Functionalization of conducting polymer with novel Co(II) complex: Electroanalysis of ascorbic acid

We report for the first time the functionalization of a conducting polymer with a metal complex in order to develop a new type of catalytic material exhibiting better electronic communication through their delocalized π electrons. The Co(II) complex having hydroxyl group as functional moiety is chemically coupled with carboxyl group of polyanthranilic acid which itself is a self doped conducting polymer. The covalent linkage between Co(II) and –OH group is confirmed using UV–vis, FT-IR and NMR spectroscopic techniques. The Co(II) complex functionalized polymer does exhibit excellent redox behavior and stability with mixed properties of Co(II) complex and π-conjugated polymer. The material possesses potential benefits in sensors/biosensor applications and it is demonstrated for the electroanalysis of ascorbic acid at a level of nano molar concentration.     

导电聚合物MEH-PPV表面光电特性的研究

用接触电位差(CPD)方法研究了导电聚合物MEH-PPV薄膜的光电特性，测得MEH-PPV的能隙为2．1eV，表面功函数为4．7-4．8eV，是p型导电材料，同时研究了不同铸膜溶剂对薄膜光电特性的影响，测得由不含芳环的四氢呋喃为溶剂制得的薄膜表面功函数比由含芳环的氯苯为溶剂制得的薄膜低0．15eV。     

Hybrid nanocrystal/polymer solar cells based on tetrapod-shaped CdSe(x)Te(1-x) nanocrystals

A series of ternary tetrapodal nanocrystals of CdSe(x)Te(1-x) with x = 0?(CdTe), 0.23, 0.53, 0.78, 1 (CdSe) were synthesized and used to fabricate hybrid nanocrystal/polymer solar cells. Herein, the nanocrystals acted as electron acceptors, and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) was used as an electron donor. It was found that the open circuit voltage (V(oc)), short-circuit current (J(sc)) and power conversion efficiency (η) of the devices all increased with increasing Se content in the CdSe(x)Te(1-x) nanocrystals under identical experimental conditions. The solar cell based on the blend of tetrapodal CdSe nanocrystals and MEH-PPV (9:1?w/w) showed the highest power conversion efficiency of 1.13% under AM 1.5, 80?mW?cm(-2), and the maximum incident photon to converted current efficiency (IPCE) of the device reached 47% at 510?nm. The influence of nanocrystal composition on the photovoltaic properties of the hybrid solar cells was explained by the difference of the band level positions between MEH-PPV and the nanocrystals.     

Electrical conductivity of (PbO)1−x (SnO) x

Electrical conductivity of lead tin monoxide has been measured as a function of composition (x), temperature and electric field. Heat treatment of samples in vacuum produces an irreversible increase in conductivity and is probably due to chemisorption of oxygen. The thermal activation energies in screen printed layers have been found to be lower than that in pressed pellets and is considered to be due to more grain boundaries being present in the former. The non ohmic electrical conduction in pellets followsJ ∝V ⁿ relationship wheren ranges between 2 and 1·25 for different compositions and temperatures. The theory of space charge limited currents (sclc) in defect insulators has been invoked to explain the observed results.     

Enhanced percolative properties from partial solubility dispersion of filler phase in conducting polymer composites (CPCs)

A variant of the standard solubility parameter concept was applied in the development of a partial-solution mixing model for this work. When correlated to polymer swelling ratios, it served as a useful tool for process control and percolation development. Polymer compositions of poly(acrylonitrile butadiene styrene) and poly(styrene butadiene styrene) block copolymers, in powder form, were classified into narrow particle size ranges and controllably coated with graphite filler in a solvent of defined solubility parameter. A percolation concentration of 0.23 vol.% was achieved for partial-solution mixing, which was a decade lower than that for a conventional solution mixing process. Further, the mean resistivity and standard deviation were much less for the classified than for a broad particle size range, by factors of ∼14 and ∼3, respectively. Compressive yield strength, used as a measure of composite cohesion, was 32 MPa, about 25–60% higher than for dry, wet or solution mixing. The application of solubility parameter as a control aid in partial-solution mixing (PSM) was found also to be an effective tool in control of electrical percolation.