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  • 1
    Electronic Resource
    Electronic Resource
    Structure of active centers and mechanism of the anionic polymerization of lactonesDedicated of Prof. O. Wichterle on the occasion of his 70th birthday (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 91-101 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of β-propiolactone (βPL) in DMF initiated with CH3COO-K+ or CH3O-K+ has been found to proceed via the carboxylate ion as growing species. This is valid for all polymerization steps in the former system, starting from the first monomer addition, whereas in the latter CH3O-K+ was found to produce in the initiation reaction both alcoholate and carboxylate anions in almost equal properties. The alcoholate reproduces approximately half of itself in each subsequent step; thus, after a few addition steps all of the active species have become carboxylate ones. The anionic polymerization of ε-caprolactone (εCL), on the other hand, can only be induced by alcoholates and the growing species are alcoholate anions. Carboxylate anions, even with crowed cations, are inactive as initiators of εCL. These conclusions are based on NMR studies of the end-groups originating from the initiator and on UV-VIs studies of the reaction products of the active species with 2,4,6-trinitroanisole. The difference between the polymerizations of βPL and εCL are explained in terms of ring strain and conformation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850110
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  • 2
    Electronic Resource
    Electronic Resource
    Anionic polymerization of exo-3,4,5-trithiatetracyclo[5.5.1.O2,6.O8,12]tridec-10-ene (dicyclopentadiene trisulfide) (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 2337-2346 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of exo-3,4,5-trithiatetracyclo[5.5.1.O2,6.O8,12]tridec-10-ene (1) in bulk and/or in aromatic solvents (benzene, toluene) was studied. The polymerization was initiated with sodium benzenethiolate (sodium cation complexed with dibenzo-18-crown-6). Polymers with high-molecular weights were obtained (Mn ≈ 105, osmometrically). The polymerization was found to be living and reversible; the equilibrium monomer concentration increases with the temperature. The ceilling temperature was estimated as 167°C. The thermodynamic data of the polymerization in toluene was determined and compared with those of the polymerization of exo-3,4,5-trithiatricyclo[5.2.O2,6]decane. The standard enthalpy ΔH0ss = -(6,6 ± 0,6)kJ · mol 1 and entropy ΔS0ss = -(29,3 ± 2,1)J · mol 1 · K 1 of the polymerization of 1 were evaluated from the temperature dependence of the equilibrium monomer concentration, determined dilatometrically.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021851111
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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