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Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red
The permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA)...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Beilstein-Institut
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839560/ https://www.ncbi.nlm.nih.gov/pubmed/31728169 http://dx.doi.org/10.3762/bjoc.15.248 |
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author | Yadigarli, Aydan Song, Qimeng Druzhinin, Sergey I Schönherr, Holger |
author_facet | Yadigarli, Aydan Song, Qimeng Druzhinin, Sergey I Schönherr, Holger |
author_sort | Yadigarli, Aydan |
collection | PubMed |
description | The permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin films on a glass support was probed by the energy of the charge transfer transition in the oxazine dye Nile red (NR) at 25 °C. The absorption and fluorescence spectra of NR were observed to shift to the red with increasing solvent polarity, because of the intramolecular charge transfer character of the optical transition. New types of solvatochromic plots of emission frequency against absorption frequency and vice versa afforded the Onsager radius-free estimation of the ground and excited states dipole moment ratio. With this approach the values of these dipole moments of 11.97 D and 18.30–19.16 D, respectively, were obtained for NR. An effective local dielectric constant of 5.9–8.3 for PMMA thin films was calculated from the solvatochromic plot and the fluorescence maximum of NR observed in the PMMA films. The fluorescence band of NR in the rigid PMMA films shifted to the red by 130 cm(−1) with increasing excitation wavelength from 470 to 540 nm, while in a series of liquids the position of the emission maximum of NR remained constant within same range of the excitation wavelength. It is concluded that the fluorescence spectrum of NR in PMMA undergoes inhomogeneous broadening due to different surroundings of NR molecules in the ground state and slow sub-glass transition (T(g)) relaxations in PMMA. |
format | Online Article Text |
id | pubmed-6839560 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Beilstein-Institut |
record_format | MEDLINE/PubMed |
spelling | pubmed-68395602019-11-14 Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red Yadigarli, Aydan Song, Qimeng Druzhinin, Sergey I Schönherr, Holger Beilstein J Org Chem Full Research Paper The permittivity of polymers and its spatial distribution play a crucial role in the behavior of thin films, such as those used, e.g., as sensor coatings. In an attempt to develop a conclusive approach to determine these quantities, the polarity of the model polymer poly(methyl methacrylate) (PMMA) in 600 nm thin films on a glass support was probed by the energy of the charge transfer transition in the oxazine dye Nile red (NR) at 25 °C. The absorption and fluorescence spectra of NR were observed to shift to the red with increasing solvent polarity, because of the intramolecular charge transfer character of the optical transition. New types of solvatochromic plots of emission frequency against absorption frequency and vice versa afforded the Onsager radius-free estimation of the ground and excited states dipole moment ratio. With this approach the values of these dipole moments of 11.97 D and 18.30–19.16 D, respectively, were obtained for NR. An effective local dielectric constant of 5.9–8.3 for PMMA thin films was calculated from the solvatochromic plot and the fluorescence maximum of NR observed in the PMMA films. The fluorescence band of NR in the rigid PMMA films shifted to the red by 130 cm(−1) with increasing excitation wavelength from 470 to 540 nm, while in a series of liquids the position of the emission maximum of NR remained constant within same range of the excitation wavelength. It is concluded that the fluorescence spectrum of NR in PMMA undergoes inhomogeneous broadening due to different surroundings of NR molecules in the ground state and slow sub-glass transition (T(g)) relaxations in PMMA. Beilstein-Institut 2019-10-25 /pmc/articles/PMC6839560/ /pubmed/31728169 http://dx.doi.org/10.3762/bjoc.15.248 Text en Copyright © 2019, Yadigarli et al. https://creativecommons.org/licenses/by/4.0https://www.beilstein-journals.org/bjoc/termsThis is an Open Access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0). Please note that the reuse, redistribution and reproduction in particular requires that the authors and source are credited. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (https://www.beilstein-journals.org/bjoc/terms) |
spellingShingle | Full Research Paper Yadigarli, Aydan Song, Qimeng Druzhinin, Sergey I Schönherr, Holger Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title | Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title_full | Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title_fullStr | Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title_full_unstemmed | Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title_short | Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red |
title_sort | probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in nile red |
topic | Full Research Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839560/ https://www.ncbi.nlm.nih.gov/pubmed/31728169 http://dx.doi.org/10.3762/bjoc.15.248 |
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