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  • 1
    Electronic Resource
    Electronic Resource
    Premembranes for porogen-derived membranes and thermal decomposition of porogens (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1065-1074 
    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: Various t-butyl and di-t-butyl esters, N-boc and di-N-boc amines, metal salts of N-boc amino acid, and glycerol-formic acid esters are potential porogens for porogen-derived membranes. Introduction of more than 20 such compounds into polysulfone or poly(vinyl chloride) films was studied. Transparency, IR spectra, changes in glass transition temperature, and differential scanning calorimetry were used to differentiate between molecular dispersion and formation of micro phases. The results show that for many of the studied additives more than 10% by weight can be practically molecularly dispersed in the polymers. The upper limit of porogen concentration in premembranes depends on characteristics of the polymer and of the porogen, on casting solvent composition, and on drying procedure. Metal salts of N-boc amino acids were found to be suitable heat-decomposable porogens. Their decomposition in premembranes proceeds in two stages, in the first of which 2 C4H8 + 2CO2 are released per salt molecule. The metal complex formed goes through decarboxylation at a higher temperature. A heating procedure for completion of the first decomposition stage and for avoiding the second was determined.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450616
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  • 2
    Electronic Resource
    Electronic Resource
    Pore formation, permeability, and permselectivity in porogen derived membranes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1621-1629 
    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: Porogen derived membranes, formed on decomposition of porogen molecules homogeneously dispersed in premembranes, were divided into two groups according to permeability and permeation mechanism. The more open membranes were formed when premembranes were cast on nonwoven polyester cloth support, or when decomposition products were extracted by solvent. The molecular cut off found for these membranes was at about 1000 Daltons and permeability was mainly determined by permeants' diffusivity and concentration. Permeability through the denser membrane was mainly determined by the permeants' partial vapor pressure, leading to high permselectivities. These denser membranes allowed relatively high osmotic water permeation while practically blocking permeation of solutes, such as salt, in the opposite direction. These membranes were thus also suitable for concentration of aqueous solutions by water removal into concentrated electrolyte solutions. © John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460910
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Metastable solutions and interactions of decomposition products in porogen derived membranes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1489-1498 
    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: Small incompatible molecules formed on porogen decomposition were found to be metastably dissolved in Porogen Derived Membranes, confirming previous analysis. 1Degrees of metastable dissolution are determined by polymer and porogen characteristics, by porogen content, and by decomposition parameters (characteristics of reagent, its concentration, and decomposition temperature). These parameters determine the characteristics of decomposition products (DPs) formed, the rate of their formation, and the properties of the matrix through which they have to diffuse for phase separation. Extraction experiments indicated that, for many compositions, leaching out of DPs during contact with water is very slow. Porogen derived membranes are thus intermediate between polymeric membranes and supported liquid membranes, with the potential of combining high selectivity and reasonable stability. © John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460821
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  • 4
    Electronic Resource
    Electronic Resource
    Chemically induced porogen decomposition in premembranes for porogen derived membranes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1613-1620 
    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: Studies of chemically induced porogen decomposition in Porogen Derived Membranes show that substantially complete decomposition of porogen molecules, molecularly dispersed in the polymeric matrix, is attainable. Several hours are required for decomposition by reagents penetrating into the premembrane at ambient. Decomposition rate is determined by characteristics of polymer, porogen, and reagent used, by polymer/porogen weight ratio, by reagent concentration, and by temperature. The concept of decomposition by an internal catalyst was also validated. In addition to direct relevance to the new method of membrane formation, the study provides better understanding of phenomena of general interest, such as transport of small molecules through changing polymeric matrices. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460909
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    Paper (German National Licenses)
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