Publication: Monitoring of curing process by fluorescence technique. Fluorescence probe and label based on 5-dimethylaminonaphthalene-1-sulfonamide derivatives (DNS)
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2001-05
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Taylor & Francis Group
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Abstract
The curing reaction of glycidyl ether bisphenol A (DGEBA) with n-butyl amine and/or N-methylethylenediamine was monitored by fluorescence spectroscopy. 5-Dimethylaminonaphthalene-1-sulfonamide (DNS) fluorophore was used as a probe and/or label. Fourier transform infrared (FTIR) analysis revealed that the rate constant for the addition reaction of the primary amino group hydrogen of n-butylamine to the epoxide ring is more than four times larger than that arising from a secondary amine. Significant differences have been observed between the fluorescence behavior of the DNS as a probe and label, especially in the system DGEBA-N-butyl amine. Integrated fluorescence intensity for the DNS label, in contrast to the DNS probe, indicates the most important changes in chemical transformations of this reaction mixture (the onset of tertiary amino groups and maximum concentration of secondary amino groups). Similarly, the dependence of the half-bandwidth on the epoxy groups conversion for the DNS label shows these stages of the curing reaction as well. In the system DGEBA-N-methylethylenediamine, the reactivity of the secondary amino group hydrogen is higher than that of the primary amino group. A change in slope of the dependence of integrated fluorescence intensity on epoxy group conversion clearly indicates the gel point and entry of the system into the glassy state. The DNS probe does not sense any of these changes. From the emission spectra of the DNS probe and/or label, the average value = SigmaIF(nu)nu/SigmaIF(nu) of the emission band position has been correlated with the epoxy group conversion determined by FTIR. Smooth dependencies were obtained in all cases. This enables one to monitor on line and in real time the epoxy group conversion.
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Bisphenol A, Dansyl probe and label, Diglycidyl ether, Epoxide curing, Fluorescence monitoring, FTIR analysis, Gel point, Glassy state
Bibliographic citation
Mikeš, F., González-Benito, J., & Baselga, J. (2001). Monitoring of curing process by fluorescence technique. Fluorescence probe and label based on 5-dimethylaminonaphthalene-1-sulfonamide derivatives (DNS). Journal of Macromolecular Science, Part B, Physics, 40 (3-4), pp. 405-428.