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  • 1960-1964  (9)
  • Chemistry  (9)
  • Analytical Chemistry and Spectroscopy
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  • 1
    Electronic Resource
    Electronic Resource
    Note on proton resonance in polystyrene solutions (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 45 (1960), S. 530-531 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204514625
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Polymer NSR spectroscopy. III. The rates of the propagation steps in the isotactic and syndiotactic polymerization of methyl methacrylate (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 46 (1960), S. 59-64 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By measurement of peak areas in the α-methyl region of the NSR spectra of 15% chloroform solutions of methyl methacrylate polymers prepared by free radical initiation over a 178° range of polymerization temperatures, it has been found that syndiotactic propagation becomes increasingly dominant as the polymerization temperature is decreased and that propagation tends toward randomness as the polymerization temperature is increased. We report the first experimental measurement of the difference in activation enthalpies and entropies for syndiotactic and isotactic monomer placement. It is found that there is no difference in the activation entropies of these processes, but that isotactic placement requires an additional activation enthalpy of 775 ± 75 cal./mole.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204614706
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  • 3
    Electronic Resource
    Electronic Resource
    Polymer NSR spectroscopyThe first paper of this series is F. A. Bovey and G. V. D. Tiers, J. Polymer Sci., 38, 73 (1959).. II. The high resolution spectra of methyl methacrylate polymers prepared with free radical and anionic initiators (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 44 (1960), S. 173-182 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectra of methyl methacrylate polymers in chloroform solution at 90° show three α-methyl proton peaks. Measurements of their areas in spectra of polymers prepared with free radical and anionic initiators indicate that these may be attributed to (1) isotactic sequences (ddd or lll), (2) syndiotactic sequences (ldl or dld), and (3) heterotactic sequences (ldd, dll, ddl, or lld). The conformation and stereochemical configuration of the chains may thus be examined with considerable discrimination; degrees of regularity, block sizes, etc. appear to be determinable. Free radical polymers of methyl methacrylate are found to be predominantly syndiotactic, whereas those produced with anionic initiators. such as n-butyllithium, are shown to be predominantly isotactic, in agreement with the findings of others. The backbone methylene resonance also shows striking changes with chain stereochemical configuration, such as to provide absolute, independent confirmation of the assigned structures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204414315
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  • 4
    Electronic Resource
    Electronic Resource
    Polymer NSR spectroscopy. V. The effect of zinc chloride on the free radical polymerization of methyl methacrylateContribution No. 188 from the Central Research Laboratory, Minnesota Mining & Mfg. Co. (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 47 (1960), S. 480-481 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204714944
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  • 5
    Electronic Resource
    Electronic Resource
    Polymer NMR spectroscopy. VI. Methyl methacrylate-styrene and methyl methacrylate-α-methylstyrene copolymersContribution No. 219 from the Central Research Department, Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 62 (1962), S. 197-209 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR spectra of methyl methacrylate-styrene and methyl methacrylate-α-methylstyrene copolymers exhibit, among other features of interest, an unexpected multiplicity in the 6.4-7.8 τ region, characteristic of methoxyl protons. This multiplicity is believed due to magnetic shielding by styrene units. By comparing the results of a statistical analysis of monomer sequence probabilities with the relative areas of the methoxyl peaks, it is shown that the degree of shielding of the methoxyl protons is dependent not only upon the presence of styrene units as nearest neighbors along the chain but also upon their stereochemical configuration with respect to the methyl methacrylate units. By means of reasonable assumptions it is possible to explain the copolymer spectra and to give a partial description of the stereochemical configuration of the methyl methacrylate-styrene copolymers. The NMR method should be valuable in the analysis of other copolymers, particularly block and graft copolymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1962.1206217315
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  • 6
    Electronic Resource
    Electronic Resource
    Polymer NSR spectroscopy. IV. The stereochemical configuration of polymethacrylic anhydrideContribution No. 187 from the Central Research Laboratories, Minnesota Mining & Mfg. Co. (1960)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 47 (1960), S. 479-480 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1960.1204714943
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  • 7
    Electronic Resource
    Electronic Resource
    Polymer NMR spectroscopy. VII. The stereochemical configuration of polytrifluorochloroethyleneContribution No. 221. (1963)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 833-841 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR spectrum of polytrifluorochloroethylene in 3,3′-bistrifluoromethylbiphenyl solution at 150°C. consists of two doublets having unequal components. Those at lower field correspond to CF2 chain units, while those at higher field correspond to CFCL units. In the CF2 doublet, the weaker component (at lower field) is found to have half the area of the stronger (at higher field), for polymers prepared over a 120°C. range of polymerization temperatures. By comparison to the spectra of the model compounds meso- and dl-CF2ClCFClCF2CFClCF2Cl, the peaks of which closely coincide with those of the polymer when both are compared at 150°C., it is concluded that of the two CF2 peaks in the polymer spectrum, the weaker one represents CF2 groups which are between monomer units in isotactic dyads whereas the stronger one represents CF2 groups which are between monomer units in syndiotactic dyads. It follows that in trifluorochloroethylene propagation, syndiotactic dyad formation is twice as probable as isotactic dyad formation. This preference for syndiotactic placement corresponds to an activation entropy for isotactic propagation 1.38 e.u. more negative than that for syndiotactic propagation; there is no difference in the activation enthalpies. This behavior is in contrast to that previously found for methyl methacrylate propagation; here, preference for syndiotactic placement is entirely dictated by a greater activation enthalpy for isotactic placement.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1963.100010301
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  • 8
    Electronic Resource
    Electronic Resource
    Polymer NMR spectroscopy. VIII. The influence of the pH of the polymerization medium on the stereochemical configuration of polymethacrylic acid (1963)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 843-848 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is shown that when methacrylic acid is polymerized in an aqueous system, the stereochemical configuration of the polymer, deduced by observation of the high resolution NMR spectra of polymethyl methacrylate samples prepared by methylation, is markedly influenced by the pH of the system. Syndiotactic propagation is favored at higher pH, presumably because coulombic repulsion between negatively charged monomer and negatively charged growing polymer radicals increases the free energy of activation for isotactic monomer placement.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1963.100010302
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  • 9
    Electronic Resource
    Electronic Resource
    Polymer NMR spectroscopy. IX. Polyacrylamide and polymethacrylamide in aqueous solution (1963)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 849-861 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR spectrum of polyacrylamide in aqueous solution exhibits a doublet resonance in the amide proton region, in contrast to the broad singlet shown by most smallmolecule amides. This is attributed to the relatively slow reorientation rate of the polymer segments, permitting effective coupling of the electric quadrupole moment of the N14 nucleus to the motions of the molecular framework. This, in turn, narrows the amide resonance to such a degree that the two protons can be discriminated. By observation of the collapse of this doublet, the rate of rotation of the amide groups can be measured; at pH 4.5 this rotation requires an activation energy of 10.5 ± 1 kcal. and is more rapid than proton exchange between the amide group and water. Rotation is not catalyzed by acid or base, where as exchange is catalyzed by both and becomes more rapid than rotation at high and low pH. The two amide protons exchange at equal rates; if intramolecular hydrogen bonding of amide groups is present, it has no apparent retarding effect on proton exchange. These results are discussed in terms of possible protonated intermediates.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1963.100010303
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