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Synthesis of polyesters containing coumarin dimer components by photopolymerization of 7,7′-coumarinyl polymethylene dicarboxylates (1994)

Chen, Yun ; Hong, Rong-Tzung

Springer

Journal of polymer research 1 (1994), S. 285-293

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ISSN: 1572-8935

Keywords: 7,7′-Coumarinyl polymethylene dicarboxylate ; Photopolymerization ; Coumarin dimer ; Polyester, Cyclobutane

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Abstract Eight 7,7′-coumarinyl polymethylene dicarboxylates have been successfully synthesized by solution condensation of 7-hydroxycoumarin (umbelliferone) or 7-hydroxy-4-methylcoumarin (4-methylumbelliferone) with various polymethylene diacid chlorides. Upon benzophenone-sensitized irradiation with 350 nm light, the terminal coumarin chromophores dimerize to form intermolecular cycloadducts or intermolecular polyesters with three kinds of cyclobutanes (syn head-to-head,anti head-to-head,anti head-to-tail), depending on structure of the dicarboxylates and reaction conditions. The structures of the cycloadducts and polyesters have been characterized by1H NMR spectra. When the methylene units exceed seven, intermolecular reaction becomes predominant and result inanti-rich configuration photo-cyclized products with higher viscosity. Lower polar solvents and 4-methyl substitution in coumarin chromophores also promote intermolecular reaction. The highest viscosity (ηred = 0.42 dL/g) is obtained with polyester from 7,7′-(4-methyl coumarinyl) decamethylene decarboxylate. Irradiation of the polyesters with 254 nm light leads to symmetric cleavage of the cyclobutane linkage in the main chain.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01374553

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Preparation and photoreaction of copolymers derived from N-(1-phenylethyl)acrylamide and 7-acryloyloxy-4-methyl coumarin (1994)

Chen, Yun ; Wu, Jehng-Daugh

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1867-1875

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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.