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  • 1
    Electronic Resource
    Electronic Resource
    ESR Study of the Plasma Polymerizations of Trimethylsilane and Methane (2000)
    Springer
    Plasmas and polymers 5 (2000), S. 235-253 
    Details
    ISSN: 1572-8978
    Keywords: ESR ; plasma polymerization ; free radical ; thin films ; trimethylsilane ; methane ; PE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Electron Spin Resonance (ESR) was used to study, at the molecular level, the plasma polymerization of trimethylsilane (TMS) and methane. Direct ESR analysis of the plasma coated Al substrate required the use of a novel ESR technique. TMS plasma deposit on Al showed a single broad resonance line near g = 2.003. The signal was stable in vacuum and decayed on exposure to air, with a significant fraction persisting for days. Results show that this signal arises from silicon dangling bonds. Identical TMS signals were observed from films prepared by the DC cathodic or the AF glow discharge method but their decay rates were different. In contrast, the deposition of methane produced two distinct types of carbon-based signals depending upon the method of deposition. TMS or CH4 films deposited by the DC cathodic method showed slow signals decay and high refractive indices value. While the use of Al as the substrate showed plasma-coating radicals, only substrate radicals were observed when PE was used as the substrate. The nature of radicals formed depends not only on the deposition method used but also on the substrate type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011377900516
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  • 2
    Electronic Resource
    Electronic Resource
    Retention, enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an alpha1-acid glycoprotein-bonded column (1992)
    Springer
    Chromatographia 33 (1992), S. 127-132 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Alpha 1-acid glycoprotein-bonded column ; Propranolol ; Propranolol ester derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an α1-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02275892
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  • 3
    Electronic Resource
    Electronic Resource
    Chiral separation of propranolol and its ester derivatives on an ovomucoid-bonded silica: Influence of pH, ionic strength and organic modifier on retention, enantioselectivity and enantiomeric elution order (1990)
    Springer
    Chromatographia 29 (1990), S. 587-592 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ovomucoid-bonded silica ; Chiral separation ; Propranolol ; Propranolol ester derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention, enantioselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propyl,-butyl and-valeryl PP) on an ovomucoid-bonded silica column have been investigated with respect to pH, ionic strength and organic modifier. For these cationic solutes, an increase in the organic modifier content and/or a decrease in the pH result in a decreased retention of both enantiomers. Enantioselectivity of the ester derivatives was higher than of underivated PP. The enantiomeric elution order was (S)/(R) for PP and (R)/(S) for the four ester derivatives, when ethanol or 2-propanol was used as the organic modifier. When methanol or acetonitrile was used as the organic modifier, inversion of the enantiomeric elution order was observed for O-valeryl PP with the use of methanol and for PP and O-propyl PP with acetonitrile. These results suggest that at least two chiral binding- or recognitionsites are present in a protein molecule and/or conformational changes occur in the chiral binding- or recognition-site(s) of the protein molecule bonded to a silica matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261228
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of plasma polymerized hydrocarbons using CP-MAS 13C-NMR (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 1801-1805 
    Details
    ISSN: 0887-624X
    Keywords: Carbon-13 NMR ; plasma polymerization ; thin films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plasma polymerized hydrocarbons made from ethane and methane were produced under different reactor conditions and probed by solid-state carbon-13 nuclear magnetic resonance (13C-NMR) with cross-polarization and magic-angle sample spinning. NMR experiments provided structural information about the plasma polymers. The conditions of low power, high hydrocarbon gas flow rate, and no added hydrogen gas appeared to give the highest amount of nonprotonated sp3 hybridized carbons in the films for the reactor design used. The use of methane or ethane as reactor gas did not affect plasma polymer structure significantly.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080291212
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  • 5
    Electronic Resource
    Electronic Resource
    Fundamental aspect and behavior of saturated fluorocarbons in glow discharge in absence of potential source of hydrogen (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1731-1739 
    Details
    ISSN: 0887-624X
    Keywords: saturated fluorocarbon ; plasma polymerization ; surface fluorination ; ESCA ; sputtering ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The glow discharge of a series of saturated fluorocarbons, CnF2n+2 (n = 1, 2, 4, 6, and 8), was studied with glass substrates which do not contain any hydrogen. It was found that the deposition rate was a function of the F/C ratio of the starting fluorocarbons. That is, fluorocarbons with higher F/C ratio, such as CF4 and C2F6, hardly polymerized, while fluorocarbons with lower F/C ratio, such as C8F18, polymerized as well as C2F4. After plasma exposure, the surface of glass substrate was characterized by measurements of water contact angle, water droplet rolling-off angle, and ESCA. Although all saturated fluorocarbon plasmas could alter the surface more hydrophobic than before, the deposited materials from fluorocarbons with higher F/C were not stable. Also, in plasmas with high F/C fluorocarbons, i.e., CF4 and C2F6, sputtering of the electrode material was observed. © 1992 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300826
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  • 6
    Electronic Resource
    Electronic Resource
    Optical emission diagnostics in cascade arc plasma polymerization and surface modification processes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1583-1592 
    Details
    ISSN: 0887-624X
    Keywords: optical emission spectroscopy ; cascade arc ; surface modification ; fluorination ; plasma polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical Emission Spectroscopy (OES) was used to identify reactive species and their excitation states in low-temperature cascade arc plasmas of N2, CF4, C2F4, CH4, and CH3OH. In a cascade arc plasma, the plasma gas (argon or helium) was excited in the cascade arc generator and injected into a reactor in vacuum. A reactive gas was injected into the cascade arc torch (CAT) that was expanding in the reactor. What kind of species of a reactive gas, for example, nitrogen, are created in the reactor is dependent on the electronic energy levels of the plasma gas in the cascade arc plasma jet. OES revealed that no ion of nitrogen was found when argon was used as the plasma gas of which metastable species had energy less than the ionization energy of nitrogen. When helium was used, ions of nitrogen were found. While OES is a powerful tool to identify the products of the cascade arc generation (activation process), it is less useful to identify the reactive species that are responsible for surface modification of polymers and also for plasma polymerization. The plasma surface modification and plasma polymerization are deactivation processes that cannot be identified by photoemission, which is also a deactivation process. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1583-1592, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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