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  • 1
    Electronic Resource
    Electronic Resource
    The different nature of the anomeric effect for methoxy and chlorine substituents
    Amsterdam : Elsevier
    Tetrahedron Letters 16 (1975), S. 249-252 
    Details
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0040-4039(00)71835-1
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  • 2
    Electronic Resource
    Electronic Resource
    Torsional potential and strain energy distribution in an extended chain under stress (1988)
    Springer
    Colloid & polymer science 266 (1988), S. 405-410 
    Details
    ISSN: 1435-1536
    Keywords: Chain elongation energetics ; stored elastic energy ; isomerisation mechanism in polymer solution ; coil-stretch conformational transition
    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 Torsional potentialV(ϕ) for the single bond transformation in an extended hexadecane, subjected to elongation, has been determined by molecular mechanics calculations. The stored elastic energy significantly modifies the potentialV(ϕ), the conformational energies and the barriers of transition. Apart from the “soft” torsional coordinate, elastic energy is also dissipated considerably by bond stretching and angle bending. Maximal variations of the valence coordinates occur in the vicinity of the torsional defect and dampen along the chain. At higher elongation, the gauche minimum on the potentialV(ϕ) disappears and the calculations predict the abrupt gauche to trans transition. The energetics of torsion of a deformed chain are compared with the experimental data on the hydrodynamic extension of polymers in dilute solution by elongational flow. The calculations also provide details of a single bond transformation mechanism at conformational interconversions in a long chain, proposed by Helfand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457256
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  • 3
    Electronic Resource
    Electronic Resource
    GPC in Misch-Elutionsmitteln. Einfluß der Sorption an Porasil-Gelen (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 622-622 
    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/BF01549872
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  • 4
    Electronic Resource
    Electronic Resource
    Über die thermische Dehydrochlorierung von Modellverbindungen des PVC. 4. MItt. MO-Untersuchung des katalytischen Effektes von HCl (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 619-619 
    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/BF01549851
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  • 5
    Electronic Resource
    Electronic Resource
    Gel chromatography with mixed eluents. Partition of solute due to preferential solvation of gel (1981)
    Springer
    Chromatographia 14 (1981), S. 163-168 
    Details
    ISSN: 1612-1112
    Keywords: Gel-permeation ; Gel solvation ; Mobile phase composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper discusses the effect of the composition of a mixed eluent inside the gel and in the mobile phase on the separation mechanism in gel chromatography. An increase in the concentration of one of the eluent components can result from the preferential solvation of the macromolecules forming the gel matrix. Different composition of the mobile and quasistationary (gel) phases can significantly influence the distribution co-efficient of the solute and make the thermodynamic partition more important within the separation process of gel chromatography. In analogy with liquid-liquid chromatography it is suggested that the contribution of thermodynamic partition can be determined with help of the activity coefficients of the solute and the composition of both phases. Experimental results for dextran and polystyrene gels in binary mixtures show the effect of the gel’s chemical structure, its polarity and degree of crosslinking on its preferential solvation. Quantitative evaluation of the preferential solvation makes it possible to determine the internal solvent composition in the column. The analogy between the description of both the preferential solvation of the gel and the surface adsorption based on the Gibbs adsorption isotherm is also pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02314761
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  • 6
    Electronic Resource
    Electronic Resource
    UV detection of solvent peaks in liquid chromatography with mixed eluents (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 860-862 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography, LC ; Solvent peaks ; Mixed eluents ; UV-visualization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240081214
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  • 7
    Electronic Resource
    Electronic Resource
    Energetics of rotation and translation in hexagonal aggregates of extended chains (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 574-583 
    Details
    ISSN: 1435-1536
    Keywords: Hexagonal disorded phases ; rotator phase ; modes of chain motion ; rotation-translation coupling ; crystall defects ; short-range order in chain assemblies
    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 Potential energy calculations have been made for hexane aggregates in the hexagonal arrangement as models of paraffin-like solids. As a part of the general energy hypersurface the feasibility of translation and rotation of extended chains in aggregate has been examined for various degrees of packing. The pure translation is favoured over the pure rotation at all interchain separations. The energy map of coupled rotation-translation motion has been developed for the intermediate degree of packing. The energy minima on the map correspond to the parallel orientation of chain backbones and are presumed to represent the prevailing short-range structure of the rotator phase in n-alkane crystals. The calculated barriers are used for the rationalization of chain dynamics in the rotator phase, and in the disorded phases with the similar alkyl chain packing as found in crystals, monolayers and bilayers of amphiphiles. Probability of formations of the translational, rotational and conformational defects in the above systems is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412772
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of adsorption and partition to the separation mechanism in gel chromatography on inorganic carriers (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2233-2244 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Gel permeation chromatography (GPC) calibration curves log hydrodynamic volume versus elution volumes were obtained from a series of single and mixed eluents for polystyrene on inorganic carriers. The observed calibration shifts were interpreted as a result of adsorption and partition effects on elution volume Ve. Secondary contributions to the separation mechanism can be qualitatively described by means of thermodynamic relations from liquid adsorption (LSC) and liquid partition (LLC) chromatography using the solubility parameters of the eluents. The universal calibration procedure based on the hydrodynamic volume of the coils is directly applicable only for systems in which adsorption and partition is approximately the same.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230802
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  • 9
    Electronic Resource
    Electronic Resource
    Thermoelasticity in open systems (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 167 (1973), S. 339-343 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden thermodynamische Zustandsgleichungen abgeleitet, die die Bestimmung des Temperaturkoeffizienten ungestörter Kettendimensionen aus thermoelastischen Messungen eines gequollenen im Phasengleichgewicht mit dem Verdünnungsmittel befindlichen Polymeren ermöglichen. Im Gegensatz zu der bislang angewandten Analyse enthalten die in der vorliegenden Arbeit abgeleiteten Gleichungen auch den Einfluß der Lösungsmittelqualität auf die ungestörten Kettendimensionen.
    Notes: Thermodynamic state equations have been derived making possible to determine the temperature coefficient of unperturbed chain dimensions from thermoelastic measurements of swollen polymer in phase equilibrium with the diluent. Unlike the analysis used previously, the equations derived in the present paper include also the effect of diluent quality on unperturbed chain dimensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021670126
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  • 10
    Electronic Resource
    Electronic Resource
    Concentration effects and thermodynamic nonideality in gel chromatography (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1903-1912 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dependence of the elution volume Ve on the concentration of injected polymer c in gel chromatography is presented for several systems including poly(styrene) and poly(methyl methacrylate) in a number of pure solvents with SiO2-based gels. The linear dependence of Ve on c and Kav on c (where Kav is the distribution coefficient) is confirmed in the region of very low concentration. The slopes k of the straight lines increase with increasing relative molecular masses M of the polymer injected and with increasing thermodynamic nonideality of the system (as expressed by the second virial coefficient A2). The significance of the slope of the GPC calibration curve for meaningful comparison of the concentration effects in various chromatographic systems is pointed out. A recently found correlation between k and (A2M)γ is confirmed with a γ value of about 0.8. A possible theoretical explanation for the deviation of γ from unity is discussed. Finally, the influence of both the polymer concentration and the thermodynamic quality of the eluent on the resolution index of the chromatographic system is evaluated with the conclusion that thermodynamically poor solvents should be preferred for preparative GPC separations with very high loads.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180211003
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