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  • 1
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of poly(4-hydroxy-2,3,5,6-tetrafluorobenzoic acid) (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 7086-7089 
    Details
    ISSN: 1520-5835
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ma00052a002
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  • 2
    Digitale Medien
    Digitale Medien
    Phase transition of thermotropic liquid crystalline copolyester film (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 1009-1010 
    Details
    ISSN: 1520-5835
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ma00028a081
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  • 3
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 853-858 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(ether sulfone) ; sodium sulfonate group ; aromatic nucleophilic substitution ; thermal degradation ; glass transition ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′-dichlorodiphenylsulfone (1) and sodium 5,5′-sulfonylbis (2-chlorobenzenesulfonate) (2) with bisphenols (3) in the presence of potassium carbonate in N,N-dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m-cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1993.080310402
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  • 4
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of poly[4-(4-hydroxyphenoxy) benzoic acid] (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1415-1421 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 4-(4-acetoxyphenoxy) benzoic acid ; polycondensation ; thermotropic liquid-crystalline polymer ; phase transition ; schlieren texture ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly[4-(4-hydroxyphenoxy) benzoic acid] was prepared by the bulk polycondensation of 4-(4-acetoxyphenoxy) benzoic acid. Polycondensation was conducted at 350°C for 3 h under a reduced pressure of 0.1 mmHg and gave a polymer with X̄n of 255. The polymer was characterized by elemental analysis, IR spectroscopy, differential scanning calorimetry, and wide-angle X-ray measurement. The crystal/nematic and nematic/isotropic phase transition temperatures of polymer, which depend on the molecular weight, were observed at about 300°C and 410°C, respectively. The polymers with low molecular weights showed nematic textures above 300°C. This nematic/isotropic phase transition temperature is lower than that of poly (4-hydroxybenzoic acid). This thermal behavior of polymer comes from ether units, which increase the flexibility (the rotation or torsion of skeletal bonds) of the polymer chain. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1994.080320802
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  • 5
    Digitale Medien
    Digitale Medien
    Preparation and permeability properties of chitosan membranes having hydrophobic groups (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 2447-2461 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Membranes consisting of N-acylated chitosan and carrying hydrophobic groups were prepared and the states of water in these membranes were examined by differential scanning calorimetry (DSC). The contents of freezable and non-freezable water were found to be closely related with the structure and properties of the membranes. On the other hand, their permeability properties for sodium salts are found to be affected considerably by modifying the membrane structure as well as the cationically charged groups. With respect to D,L-amino acids, the selective permeation of the L-isomer was enhanced in the hydrophobic chitosan membrane, suggesting the possibility to separate optical isomers by membrane transport.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1991.021921022
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  • 6
    Digitale Medien
    Digitale Medien
    Ion transport and states of water in charged poly(allylamine) membranes (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 303-314 
    Details
    ISSN: 0887-6266
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Cationically charged poly(allylamine) (PAA) membranes having various water contents [0.49 〈 H 〈 0.63 (g H2O/g wet membrane)] were prepared. Sorption and permeation of simple salts (sodium chloride and sodium tetraphenylborate) were investigated, taking into account the state of the water in these membranes. The weight ratios of freezable water and free water to total water (Wfz/Wt, and Wf/Wt) in the membranes were estimated by means of DSC and pulsed 1H-NMR measurements, respectively. Partition coefficients K for total water were converted into those in freezable and free water, Kfz and Kf, using Wfz/Wt and Wf/Wt. The permeability of both salts in the membranes could be interpreted satisfactorily by an equation derived from the Teorell-Meyer-Sievers theory using values of Kf. The free water is mainly involved in the permeation of simple salts through PAA membranes while bound water hardly takes part.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/polb.1990.090280305
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