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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and photoreaction of copolymers derived from N-(1-phenylethyl)acrylamide and 7-acryloyloxy-4-methyl coumarin (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1867-1875 
    Details
    ISSN: 0887-624X
    Keywords: N-(1-phenylethyl)acrylamide ; 7-acryloyloxy-4-methyl coumarin ; copolymerization ; monomer reactivity ratio ; photocrosslinking ; photocleavage ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymers containing photoreactive 4-methyl coumarin pendant groups have been prepared by radical copolymerization of N-(1-phenylethyl)acrylamide (M1) and 7-acryloyloxy-4-methyl coumarin (M2) in DMF at 70°C. The monomer reactivity ratios (MRR) of M1 and M2 are estimated by Finenam-Ross, Kelen-Tüdos, Mayo-Lewis, and YBR methods to be about r1 = 0.12-0.16 and r2 = 1.13-1.28. Dilute dioxane solutions of the copolymers (10-4-10-5 M of 4-methyl coumarin chromophores) are first photocrosslinked intramolecularly by irradiating 350 nm light (dimerization of 4-methyl coumarin) and then photo-cleaved at 254 nm (symmetric cleavage of cyclobutane). Tracing by an UV-visible spectrophotometer, it is found that photocrosslinking and photocleavage proceed simultaneously when 254 nm is the light source and finally reaches to a dynamic equilibrium. However, only photocrosslinking can be observed under 350 nm light. Kinetic results show that both photocrosslinking and photocleavage are first-order reactions. Moreover, photocrosslinking rate constant increases with mole fraction of M2 in the copolymer (F2). On the contrary, rate constant of photocleavage decreases with increasing F2. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321007
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation and photocrosslinking behaviors of polyesters derived from trans-2,2′-dihydroxystilbene (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1319-1327 
    Details
    ISSN: 0887-624X
    Keywords: coumarin dimer ; photocleavage ; trans-2,2′-dihydroxystilbene ; interfacial polycondensation ; photocrosslinking ; characteristic curve ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The monomer, trans-2,2′-dihydroxystilbene (DHS), has been prepared by asymmetric photocleavage (254 nm) of coumarin dimer acid derived from coumarin dimer. Four new polyesters are successfully synthesized by interfacial polycondensation of the DHS with adipoyl chloride, azelaoyl chloride, sebacoyl chloride, and dodecanedioyl dichloride, respectively. The reduced viscosities of the polyesters decrease from 0.32 to 0.11 dL/g as the number of methylene unit in diacid chlorides increases from 4 to 10. From DSC investigation, it is found that the polyesters are semi-crystalline polymers with Tm = 39-192°C. Under 350 nm light, photocrosslinking behavior in solution and film-state is investigated by UV spectral change with irradiation time (350 nm). The photoreactive stilbene chromophores in the main chain dimerize to form cyclobutane derivatives, and lead to crosslinking of the polyesters. Photosensitivity in the film state has also been evaluated by their characteristic curves. Polyester from dodecanedioyl dichloride (5d) exhibits the highest initial reaction rate and ultimate crosslinking ratio. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330814
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    Paper (German National Licenses)
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