Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited
A kinetic model for the description of non-monoexponential decay of unimolecular reactions in amorphous polymers is developed. The thermal decay of the merocyanine (MC) form of 1,3′,3′-trimethyl-6-nitrospiro-[2H-1-benzopyran-2,2′-indoline] (spiropyran, SP) in poly(alkyl methacrylates) is taken as an...
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1997
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895647_v101_n39_p7680_Levitus http://hdl.handle.net/20.500.12110/paper_10895647_v101_n39_p7680_Levitus |
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paper:paper_10895647_v101_n39_p7680_Levitus2023-06-08T16:06:37Z Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited Amorphous materials Fluorescence Glass transition Mathematical models Micelles Polyacrylates Pyrolysis Quenching Reaction kinetics Relaxation processes Thermal effects Arrhenius behavior Spiropyran merocyanine Aromatic polymers A kinetic model for the description of non-monoexponential decay of unimolecular reactions in amorphous polymers is developed. The thermal decay of the merocyanine (MC) form of 1,3′,3′-trimethyl-6-nitrospiro-[2H-1-benzopyran-2,2′-indoline] (spiropyran, SP) in poly(alkyl methacrylates) is taken as an example. The model assumes that the time dependent first-order rate constant describing the decay relaxes from an initial value k0 to a completely relaxed value L∞ with a relaxation time τm that depends on the matrix. A rate equation similar to the one provided by this model is found in fluorescence quenching either in micelles or in the picosecond range in solution. The fit of the temperature dependent decays of MC to SP with this model is as good as or better than the one obtained by other models such as the sum of exponential terms or the stretched exponential equation. The simple relaxation picture is unable to account for the decay at temperatures far below the glass transition temperature of the polymer. In this range, the average values of rates, represented by k0, k∞, and τm, poorly describe the real distribution of them. The values of k0, k∞, and τm for MC decay show an Arrhenius behavior in the polymers studied. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895647_v101_n39_p7680_Levitus http://hdl.handle.net/20.500.12110/paper_10895647_v101_n39_p7680_Levitus |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Amorphous materials Fluorescence Glass transition Mathematical models Micelles Polyacrylates Pyrolysis Quenching Reaction kinetics Relaxation processes Thermal effects Arrhenius behavior Spiropyran merocyanine Aromatic polymers |
| spellingShingle |
Amorphous materials Fluorescence Glass transition Mathematical models Micelles Polyacrylates Pyrolysis Quenching Reaction kinetics Relaxation processes Thermal effects Arrhenius behavior Spiropyran merocyanine Aromatic polymers Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| topic_facet |
Amorphous materials Fluorescence Glass transition Mathematical models Micelles Polyacrylates Pyrolysis Quenching Reaction kinetics Relaxation processes Thermal effects Arrhenius behavior Spiropyran merocyanine Aromatic polymers |
| description |
A kinetic model for the description of non-monoexponential decay of unimolecular reactions in amorphous polymers is developed. The thermal decay of the merocyanine (MC) form of 1,3′,3′-trimethyl-6-nitrospiro-[2H-1-benzopyran-2,2′-indoline] (spiropyran, SP) in poly(alkyl methacrylates) is taken as an example. The model assumes that the time dependent first-order rate constant describing the decay relaxes from an initial value k0 to a completely relaxed value L∞ with a relaxation time τm that depends on the matrix. A rate equation similar to the one provided by this model is found in fluorescence quenching either in micelles or in the picosecond range in solution. The fit of the temperature dependent decays of MC to SP with this model is as good as or better than the one obtained by other models such as the sum of exponential terms or the stretched exponential equation. The simple relaxation picture is unable to account for the decay at temperatures far below the glass transition temperature of the polymer. In this range, the average values of rates, represented by k0, k∞, and τm, poorly describe the real distribution of them. The values of k0, k∞, and τm for MC decay show an Arrhenius behavior in the polymers studied. |
| title |
Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| title_short |
Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| title_full |
Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| title_fullStr |
Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| title_full_unstemmed |
Novel kinetic model in amorphous polymers. Spiropyran-merocyanine system revisited |
| title_sort |
novel kinetic model in amorphous polymers. spiropyran-merocyanine system revisited |
| publishDate |
1997 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10895647_v101_n39_p7680_Levitus http://hdl.handle.net/20.500.12110/paper_10895647_v101_n39_p7680_Levitus |
| _version_ |
1768542424543526912 |