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  • 1
    Electronic Resource
    Electronic Resource
    Immobilization of human thrombomodulin onto PTFE (1997)
    Springer
    Journal of materials science 8 (1997), S. 789-791 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Human thrombomodulin (hTM) is an endothelial cell-surface glycoprotein and has effective anticoagulant properties. This protein was immobilized onto polytetrafluorethylene (PTFE) surfaces to create biomaterials with enhanced haemocompatibility. The PTFE surface was functionalized by CO2 plasma activation and subsequent vapour-phase graft polymerization of acrylic acid. Surface characterization after plasma treatment, grafting and hTM immobilization was achieved by attenuated total reflection-Fourier transform–infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential and wetting measurements. The activity of immobilized hTM was estimated using the protein C activation test.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018572931351
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  • 2
    Electronic Resource
    Electronic Resource
    The versatile surface properties of poly(cyclopentadiene)-modified silica particles (PCPD–silica): XPS and electrokinetic studies (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 930-939 
    Details
    ISSN: 1435-1536
    Keywords: Key words Polymer ; silica hybrid materials ; cationic surface polymerization ; poly(cyclopentadiene) ; X-ray photoelectron spectroscopy ; particle electrophoresis ; solvatochromic measurements ; acid-base properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Surface properties of poly(cyclopentadiene)–silica hybrid particles (PCPD–silica) were studied by means of XPS and electrokinetic measurements. The surfaces of PCPD–silica particles exhibit two different areas with different properties: bare silica holes and PCPD patches. The PCPD chains contain different functional groups such as alcohol and carbonyl groups that were identified by XPS. The PCPD chains are grafted covalently onto the silica surface via Si–O–C bonds created by the reaction of silanol groups and active PCPD chains. The amount of Si–O–C was examinated by means of XPS. The Brønsted acidity of the residual silanol groups was determined by means of electro-kinetic measurements. It was found that the pK a values of the residual silanol groups increase with increasing polymer content on the particle surface. The surface acceptor strengths of the hybrid particles in non-aqueous liquids were investigated by the solvatochromic indicator bis(1,10-phenanthroline)-cis-dicyano-iron-II in 1,2-dichloroethane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050330
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  • 3
    Electronic Resource
    Electronic Resource
    Adsorption of ions onto polymer surfaces and its influence on zeta potential and adhesion phenomena (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 434-442 
    Details
    ISSN: 1435-1536
    Keywords: Key words zeta potential ; atomic force microscopy ; X-ray photoelectron spectroscopy ; adhesion ; dispersion forces ; ion adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The adhesion behavior that governs many technologically and biologically relevant polymer properties can be investigated by zeta potential measurements with varied electrolyte concentration or pH. In a previous work [1] it was found that the difference of the adsorption free energies of Cl- and K+ ions correlates with the adhesion force caused by van der Waals interactions, and that the decrease of adhesion strength by adsorption layers can be elucidated by zeta potential measurements. In order to confirm these interrelations, zeta potential measurements were combined with atomic force microscopy (AFM) measurements. Force–distance curves between poly(ether ether ketone) and fluorpolymers, respectively, and the Si3N4 tip of the AFM device in different electrolyte solutions were measured and analysed. The adsorption free energy of anions calculated from the Stern model correlates with their ability to prevent the adhesion between the polymer surface and the Si3N4 tip of the AFM device. These results demonstrate the influence of adsorption phenomena on the adhesion behavior of solids. The results obtained by AFM confirm the thesis that the electrical double layer of solid polymers in electrolyte solutions is governed by ion adsorption probably due to van der Waals interactions and that therefore van der Waals forces can be detected by zeta potential measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050263
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  • 4
    Electronic Resource
    Electronic Resource
    Einfluß der Feinstruktur auf das ξ-Potential synthetischer Faserstoffe (1969)
    Springer
    Colloid & polymer science 235 (1969), S. 1243-1244 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01542535
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  • 5
    Electronic Resource
    Electronic Resource
    Characterisation of pure or coated metal surfaces with streaming potential measurements (1997)
    Springer
    Fresenius' journal of analytical chemistry 358 (1997), S. 255-258 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the field of corrosion prevention, the characterisation of metal surfaces is useful to obtain information about the necessary preparation of the surface and about the quality of thin coatings of coupling and protective agents. Electrokinetic measurements can be used to determine the properties of modified polymer surfaces, metal sheets, and different surface preparations. However, it was necessary first to create special conditions for measuring the streaming potential, such as electrical isolation of the sample sheets together with the use of inert systems, as shown by the example of aluminium. According to the usual procedure the metal was first coated with a thin layer of a coupling agent. The effect of this adhesive agent depends on the degree of its adsorption by the metal surface. The quality of this layer can be characterised by streaming potential measurements, which can show the degree of coverage, the adhesive strength of the coated layer, and the effective chemical properties of the treated surface. These results were confirmed by wetting measurements. The production of surfaces which allow us to couple a coating varnish to the adhesive agent in good quality was demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050399
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  • 6
    Electronic Resource
    Electronic Resource
    The high mass range time-of-flight secondary ion mass spectra of different polyarene films on silver (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 684-687 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to investigate thin films of poly(styrene), poly(vinyl napthalene), and poly(4-chlorostyrene) on clean silver substrate surfaces. The mass spectra were taken in the high molecular mass range (m/z〉1000 amu). The different fragmentation patterns found are discussed in detail. Obviously, the fragmentation mechanisms are influenced by the electron density of the aryl rings stabilizing or destabilizing the formed cations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050234
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  • 7
    Electronic Resource
    Electronic Resource
    Flow sorption calorimetry, a powerful tool to investigate the acid-base character of organic polymer surfaces (1997)
    Springer
    Fresenius' journal of analytical chemistry 358 (1997), S. 244-247 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Flow sorption calorimetry (FSC) can be a useful tool to estimate the Lewis acid-base behaviour of the surface of organic polymers with less than 1 m2/g surface area. Polyethylene powders grafted with different amounts of acrylic acid have been chosen as samples. The surface of the powders was investigated by means of X-ray photoelectron spectroscopy (XPS) at first and than brought into contact with the strong electron donor triethylamine in a special FSC measuring system. The heat of the displacement isotherm together with the surface excess isotherm of triethylamine adsorbed onto the powders was determined. The results obtained with FSC and XPS were well correlated and gave a comprehensive picture of the acidic surface character of modified polyethylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050396
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  • 8
    Electronic Resource
    Electronic Resource
    Wetting of solids by liquids with low and high viscosity (1997)
    Springer
    Colloid & polymer science 105 (1997), S. 44-54 
    Details
    ISSN: 1435-1536
    Keywords: Wetting ; contact angle ; surface tension ; polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An overview is given on measuring techniques for contact angles between smooth solids and liquids, solid-vapor surface tension of rough and porous solids, and wetting behavior of polymer melts. It has been shown that on non-inert polymer surfaces, such as maleimide copolymers and polystyrenes, Young contact angles can be obtained by dynamic contact angle measurements using liquids that do not swell the polymer. In the case of rough and porous polymer systems, such as polymer powders, a capillary penetration technique is suitable to determine their solid-vapor surface tension, but this method cannot reveal polar groups burried in the surface region of grafted polymers. It was shown that these polar groups can be characterized by receding contact angles. Using thin fibers for the reinforcement of polymers, contact angle measurements with pure test liquids on the individual fibers and the solid polymer matrix at room temperature are not suitable to elucidate the complex wetting processes between the fiber and the polymer matrix under processing conditions. A device for direct wetting measurements between individual fibers and polymer melts at high temperatures, comparable with processing conditions of the composites, and first results are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01188924
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  • 9
    Electronic Resource
    Electronic Resource
    Symposium „Elektrokinetische Erscheinungen ‚85-Meßtechnik und Anwendungen“ Dresden, 15./16.04.1985 (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 193-194 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414850
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  • 10
    Electronic Resource
    Electronic Resource
    Carbenium ion pairs on silica: UV-spectroscopic and electrokinetic measurements of triarylmethylium/halide-aerosil in 1,2-dichloroethane (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 99-107 
    Details
    ISSN: 1435-1536
    Keywords: Cationic interfacial polymerization ; zeta-potential ; triarylmethyl halide ; silica ; carbenium ion pair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interaction of carbenium ion pairs with silica is studied by means of UV-spectroscopy, electrokinetic and adsorption measurements using triphenylmethyl derivatives, (RC6H4)3CX, (X=F, Cl, Br, SCN, OH; R=Cl, I, H, CH3, C(CH3)3, OCH3, N(CH3)2) in interaction with silica particles suspended in 1,2-dichloroethane. The adsorption of triarylmethyl-halides onto silica is accompanied by the heterolytic dissociation of the tertiary carbonhalogen bond. The degree of ionization depends on the basicity of the counter anion and acidity of the cation, respectively. The influences of both concentration and structure of triarylmethyl halides on the zeta-potential are discussed with regard to steric and electronic factor. The zeta-potential values of the adsorbates decrease significantly, as compared with the free silica surface, from a certain triarylmethyl halide concentration where ionization takes place, to a constant level which is characteristic of the carbenium ion pair. These constant zeta-potential values of the adsorbates depend on the basicity of the counter ion and the σ p Hammett constants of the ring substitutents, with exclusion of sterically hindered substituents and salt derivatives, e.g., crystal violet and malachite green.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653314
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