Microfabrication and microsensors

In order to fabricate microsensors, a micromachining, microfabrication technique based on LSI technologies has been used. In this paper, useful micromachining techniques are described. Examples of integrated microsensors, such as a pressure sensor including a readout circuit and a multisensor cell for blood gas analysis, are introduced. Microflow control devices, such as a microvalve and a micropump for integrated chemical analysis systems, are also described.     

Kinetics of contact electrification between metals and polymers

Kinetics of charge transfer between metals and polymers was studied using an analytical rolling-sphere tool. The rates of charge transfer were related to the area of contact between contacting surfaces and the tunneling current between them. The derived rate equations accounted for the experimentally observed sigmoidal charging curves. Furthermore, for a model system of steel spheres rolling on modified polystyrene supports, it was shown that the magnitudes of separated charges can be varied by adjusting the polymer's surface properties and/or ambient conditions.     

Voltammetric determination of heavy metals leached from ceramics

Anodic stripping voltammetry using a mercury film electrode (MFE) and hanging mercury drop electrode (HMDE) was applied for the determination of trace amounts of lead, cadmium, zinc and copper leached from plates by 4% acetic acid standard solution. The use of a MFE, the fast scan rate (1000 mV/s) by DC voltammetry with subtraction of background current allowed to determine low concentrations of heavy metals. The amounts of metals leached from ware were Pb: 0.1 to 25, Cd: 0.015 to 0.44, Zn: 0.07 to 1.06, Cu: 0.14 to 0.40 μg/mL, depending on the kind of plate and manufacture. Determinations of copper and zinc were carried out using the HMDE electrode in the leachate, determination of tin after medium exchange, and thallium after complexing of lead by EDTA. A significant decrease of metals leached during the second leaching and after washing with detergent solution was found for plates with overglaze decoration. Received: 5 November 1997 / Revised: 24 February 1998 / Accepted: 26 February 1998     

Some new chelating polymers for toxic metals

Several novel polymers capable of binding mercury(II) have been prepared, all of which contain mercaptal linkages. Their selectivity for binding mercury(II) in preference to other metal ions varies considerably as the structures are varied. Those prepared from terephthaldicarboxaldehyde and polythiols tend to be fairly selective, while one prepared from glutaraldehyde and pentaerthritol tetrathioglycolate is less selective and tends to bind lead, cadium and copper, as well as mercury.     

Synthesis,structural characteristics,and thermal expansion behavior of zirconium phosphate ceramics with d-transition metals

Journal of Sol-Gel Science and Technology - The series M0.5(1+x)FexZr2?x(PO4)3 (M—Ni, Cu, Mn) with Sc2(WO4)3-related structure (SW) were prepared using Pechini technique and...     

Flammability of macrocyclic polymers and their complexes with metals

The peculiarities of thermal degradation and the flammability of nitrogen-containing macrocyclic polymers have been investigated. It has been shown that the thermal and thermo-oxidative stability of these polymers depend on the structure of the macrocycle, the type of organic radicals of the main unit and the metal nature. The effect of the type of n-conjugated macromolecules, as well as of the planarity and symmetry of macrocycle, on thermal stability as well as flammability of macrocyclic polymers has been studied. Metals (Cu, Co, Ni) in the coordination sphere increase the thermal stability and decrease the thermo-oxidative degradation of macrocyclic polymers.     

Synthesis of poly-yne polymers containing transition metals,disilane, disiloxane and phosphine groups in the main chain

The synthesis and characterization of metal poly-yne polymers containing disilane, disiloxane and phosphine groups in the main chain are described. The platinum and palladium poly-yne polymers were synthesized by polycondensation reactions between a metal chloride and an α, ω-bisethynyl complex in amines in the presence of cuprous iodide as a catalyst. The nickel poly-yne polymers were synthesized by an alkynyl ligand exchange reaction between a nickel acetylide and an α, ω-bisethynyl complex in diethylamine in the presence of cuprous iodide as a catalyst. The reaction of the platinum poly-yne polymer, containing disiloxane groups in the main chain, with copper (I) salts afforded adducts of η-²-bonded σ-acetylide polymer complexes. The reactions of the palladium poly-yne polymer, containing phosphine groups in the main chain, with transition-metal carbonyl complexes afforded polymer complexes which have phosphorus in the main chain-transition-metal bonds. A concentrated solution of the platinum poly-yne polymer containing disiloxane groups in the main chain forms a lyotropic liquid crystal in dichloromethane or 1, 2-dichloroethane.     

Polymer derived non-oxide ceramics modified with late transition metals

This tutorial review highlights the methods for the preparation of metal modified precursor derived ceramics (PDCs) and concentrates on the rare non-oxide systems enhanced with late transition metals. In addition to the main synthetic strategies for modified SiC and SiCN ceramics, an overview of the morphologies, structures and compositions of both, ceramic materials and metal (nano) particles, is presented. Potential magnetic and catalytic applications have been discussed for the so manufactured metal containing non-oxide ceramics.     

微制造技术与仿生壁虎腿

壁虎甚至在真空中都可以在垂直光滑的玻璃墙壁上纹丝不动和爬行,显然,这不可能是摩擦力和真空吸力所致,它不分泌任何液体,也不可能是通常的粘合剂作用。对壁虎脚足刚毛吸力的精确测定表明,壁虎腿与物体表面的吸力完全是范德华力相互作用。本文详细介绍了有关壁虎腿仿生研究的最新进展和可能的制备壁虎胶带的微制造方法。     

Thermal analysis of composites based on crystalline polymers and metals

Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and infrared (IR) spectroscopy have been used to examine the chemical and physical changes (crystallinity, accumulation of oxygen-containing groups, etc.) during thermal oxidation of polyethylene, polypropylene and Penton contained in coatings and metalfilled films, taking into account the thickness of the polymer layer and catalytic activity of the metal.

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Zusammenfassung DSC, thermogravimetrische Analyse (TG) und infrarot (IR) Spektroskopie wurden zur Untersuchung der während der thermischen Oxidation von in Belägen und metallgefüllten Filmen enthaltenem Polyäthylen, Polypropylen und Penton stattfindenden chemischen und physikalischen Veränderungen (Kristallinität, Anhäufung stickstoffhaltiger Gruppen usw.) eingesetzt. Hierbei wurden die Stärke der Polymerschicht und die katalytische Aktivität des Metalls in Betracht genommen.

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Temperature-dependence of interfacial energies between solid oxide ceramics and liquid metals

The interfacial energies between solid oxide ceramic and liquid metals have been investigated for a number of systems. At the metal melting point: (1) the interfacial energies between a given oxide ceramic and various metals vary by less than 10%: _SL=2.538±0.139 J/m² for Al₂O₃-liquid metals; _SL=1.599+0.064 J/m² for ZrO₂-liquid metals; _SL=1.676±0.142 J/m² for UO₂-liquid metals; (2) the respective contact angles (>90°) idicate no wettability. Linear temperature functions of the interfacial energies in oxide ceramic-liquid metal systems have been derived. By extrapolation, temperature coefficients of interfacial energies can be estimated for oxide ceramic-liquid metal systems that have not yet been measured. The interfacial energies, together with the surface energies of the materials concerned, also provide the work of adhesion for all Al₂O₃- and ZrO₂-liquid metal combinations considered.

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Zusammenfassung Grenzflächenenergien zwischen festen Oxidkeramiken und flüssigen Metallen wurden für eine Reihe von Systemen untersucht. Beim Schmelzpunkt des Metalls: (1) variieren die Grenzflächenenergien _SL zwischen einer Keramik und verschiedenen Metallen um weniger als 10%: für Al₂O₃- Metall _SL=(2.538±0.139) J m^–1 ZrO₂ - Metall _SL=(1,599±0,064) J m^–2 UO₂ - Metall _SL=(1,676±0,142) J m^–2 (2) zeigen die Kontaktwinkel (>90°) keine Benetzung.Die Grenzflächenenergien in Oxidkeramik-Metallschmelze-Systemen hängen linear von der Temperatur ab. Temperaturkoeffizienten der Grenzflächenenergien nicht untersuchter Keramik-Metallschmelze-Systeme lassen sich durch Extrapolation ermitteln. Aus den Grenzflächenenergien und den Oberflächenenergien der beteiligten Materialen wird die Adhäsionsarbeit für die untersuchten Al₂O₃- bzw. ZrO₂-Metallschmelze-Systeme erhalten.

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- . , , 10%: _SL=2,538±0,139 ·^–2 l₂₃ - _SL=1,599±0,064 ·^–2 ZrO₂ - _SL=1,676±0,142 ·^–2 UO₂ - (>90°) . — . — . — .

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The present work was performed in the frame of bilateral German-Greek cooperation in science and technology. It was sponsored financially by the Deutsche Forschungsgemeinschaft Bonn and supported by the Internationales Büro, Kernforschungsanlage Jülich. The authors gratefully acknowledge this assistance.     

Influence of constant magnetic field on electrodeposition of metals,alloys, conductive polymers,and organic reactions

The paper presents and summarizes some research on constant magnetic field effects in chemistry. Metals and alloys electrodeposited under constant magnetic field have greater thickness and smoother surface with finest grains. Metallic materials deposited under the influence of uniform magnetic field may have stronger corrosion resistance, than those obtained without the presence of magnetic field. Constant magnetic field also causes an increase of the electropolymerization rate and yield of some organic reactions. Our research also shows that the presence of constant magnetic field affects the electrodeposition process of alloys and their morphology to a great extent. The effects of magnetic field on metals, alloys, composites, polymers and other materials are due to the Lorentz force and the magnetohydrodynamic effect. It is possible that the further development of magnetoelectrodeposition will allow for using the constant magnetic field to improve the properties of metal coatings, alloys, polymers, and other materials in the industry.     

Chelating polymers and related supports for separation and preconcentration of trace metals

This review is concerned mainly with the applications of chelating polymeric resins for the separation and concentration of trace metals from oceans, rivers, streams and other natural systems. Commercially available resins, specially prepared polymers and a selection of other sorbents are described and their uses outlined. Special emphasis is placed on the preconcentration of uranium from sea-water.     

Studies on polyyne polymers containing transition metals in the main chain. VII. Synthesis and characterization of palladium-polyyne polymers

Metal-polyyne polymers consisting of palladium and conjugated acetylenic systems, where P_D and R represent the —Pd(PBu₃)₂—moiety and alkyl groups, respectively, were prepared by polycondensation between palladium chlorides and α,ω-diethynyl compounds in amines using a catalytic amount of cuprous iodide. The molecular weights of the polymers formed were greatly affected by the basicity of the amines and the addition of free phosphines to the polymerization system. Under the optimum conditions, i.e., in the presence of CuI and PBu₃ (in molar ratio 1/4) in piperidine at room temperature, polymer Ia (R¹ = R² = H) having M?_w = 29,000 was obtained.     

Highly crosslinked ionic β-cyclodextrin polymers and their interaction with heavy metals

A new aqueous insoluble ionic β-cyclodextrin polymer (PYR) has been synthesized and a potentiometric study of the binary Cu(II)-PYR system is performed to calculate the complexation constants (as logβ in heterogeneous medium). The mathematical processing of the pH-metric data gave the formation constants of Cu(II) complexes and the related species distributions. The model is compatible with the presence of five complex species in the range of pH 2.5–7. Stoichiometry indicates the probable involvement of the alcoholate functionalities of the ligand in the complexation. The capacity of the polymer with respect to metal ions retention is evaluated for both Cu(II) and Cd(II) (chosen as target probes). The possibility to recover the sorbed Cd(II) is also tested by using acidic pH solutions. A complete recovery is obtained and the stability of the polymer is verified over ten steps of retention and desorption. To understand the complexation mechanism involved, two other cyclodextrin-based polymers are synthesized which are characterized by the presence of naphthalic dicarboxylic and carbonate groups as spacers. Their interactions with Cu(II) or Cd(II) are studied. Since the β-cyclodextrin polycarbonate polymer does not have acidic groups on the spacer, it is interesting to compare metal ions retention between this material, which does not present a real cation exchange site, and PYR.     

Complexation of unsaturated carbon-carbon bonds in pi-conjugated polymers with transition metals.

The present paper explores the possibility of preparing pi-conjugated organometallic polymer hybrid systems based on a poly(p-phenylene ethynylene) (PPE) derivative, in which the ethynylene moieties of the polymer are coordinated to platinum(II) centers. The use of the "bifunctional" [Pt-(mu-Cl)Cl(PhCH=CH(2))](2) (2) allows, under appropriate conditions, the formation of three-dimensionally cross-linked, conjugated PPE-platinum(II) networks. The synthesis of [Pt-(mu-Cl)Cl(PhC(triple bond)CPh)](2), as a model compound, and a series of model reactions of 2 with diphenylacetylene (3) have enabled an NMR study which has revealed a number of equilibria, and suggests a mixed Pt-styrene-acetylene complex as a key structure. As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift upon complexation with 2.     

Nanocomposites of polymers and metals or semiconductors: Historical background and optical properties

Upon transmission of visible light through composites comprising of a transparent polymer matrix with embedded particles, the intensity loss by scattering is substantially reduced for particle diameters below 50–100 nm (nanoparticles, nanosized particles). As a consequence, related materials (nanocomposites) have found particular interest in optical studies. The first part of this article deals with a historical survey on nanoparticles and nanocomposites and the importance of small particle sizes on their optical properties. The second part focuses on results from our laboratory concerning nanocomposites with extremely high or low refractive indices and dichroic nanocomposites and their application in bicolored liquid crystal displays (LCD). The inorganic colloids required for these studies (lead sulfide, iron sulfides, gold, and silver) were prepared in situ in presence of a polymer or isolated as redispersable metal colloids modified at the surface with a self‐assembled monolayer (SAM) of an alkanethiol. The nanocomposites themselves were finally obtained by coprecipitation, spin coating, solvent casting or melt extrusion, with poly(ethylene oxide), gelatin, poly(vinyl alcohol) and polyethylene as matrix polymers.     

Studies of poly-yne polymers containing transition metals in the main chain : III. Synthesis and characterization of a poly-yne polymer containing mixed metals in the main chain,

By the reaction of trans-(PBu₃)₂Pt(CCCCH)₂ with trans-(PBu₃)₂PdCl₂, the title polymer,

(II), has been prepared and characterized by spectral and analytical data. The alternating regularity of the metal arrangement in II was confirmed by the selective formation of the trinuclear complex trans,trans,trans-ClPd(PBu₃)₂?CCC CPt(PBu₃)₂?CC-CCPd(PBu₃)₂(XXIII), in the depolymerization by trans- (PBu₃)₂PdCl₂ using CuI as catalyst in XXNEt₂.