Radiative and nonradiative excited state processes for studying the sol to gel evolution

The sol to gel evolution of systems based on the hydrolysis of titanium n-butoxide, Ti(OBu n ) 4 , in 1-butanol was investigated by monitoring the changes of the radiative and nonradiative electronic excited state processes of embedded dyes (cresyl violet and 4-(dicyanomethylene)-2-methyl-6(p-dimeth...

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Autores principales:	Marchi, María Claudia, Aldabe Bilmes, Sara Alfonsina Dora, Negri, Ricardo Martin
Publicado:	2002
Materias:	Excited states Anisotropy Chromophores Electron energy levels Fluorescence Gelation Hydrolysis Nanostructured materials Neutron scattering Nuclear magnetic resonance Percolation (fluids) Photoacoustic effect Raman spectroscopy Sol-gels
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07437463_v18_n18_p6730_Marchi http://hdl.handle.net/20.500.12110/paper_07437463_v18_n18_p6730_Marchi
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_07437463_v18_n18_p6730_Marchi
record_format	dspace
spelling	paper:paper_07437463_v18_n18_p6730_Marchi2023-06-08T15:44:50Z Radiative and nonradiative excited state processes for studying the sol to gel evolution Marchi, María Claudia Aldabe Bilmes, Sara Alfonsina Dora Negri, Ricardo Martin Excited states Anisotropy Chromophores Electron energy levels Fluorescence Gelation Hydrolysis Nanostructured materials Neutron scattering Nuclear magnetic resonance Percolation (fluids) Photoacoustic effect Raman spectroscopy Sol-gels The sol to gel evolution of systems based on the hydrolysis of titanium n-butoxide, Ti(OBu n ) 4 , in 1-butanol was investigated by monitoring the changes of the radiative and nonradiative electronic excited state processes of embedded dyes (cresyl violet and 4-(dicyanomethylene)-2-methyl-6(p-dimethylaminostyryl-4H-pyran). Fluorescence anisotropy experiments (FA) allow determination of changes in the microviscosity of the medium surrounding the fluorophore through the sol-gel evolution. The increase of the anisotropy parameter, 〈r〉, is explained in terms of solvent confinement in cavities enclosed within cross-linked polymeric chains. The acoustic signal recorded in laser-induced optoacoustics experiments (LIOAS) is attenuated as the system loses fluidity, with a minimum at t g , thus providing an alternative method for determining the gelation point. In addition, within the theoretical approach of percolation theory, the exponent of the viscosity power law is obtained from the attenuation of the sound wave. Although both FA and LIOAS provide information on the degree of cross-linking between polymeric chains, there is a clear difference between the behavior of the macroscopic shear viscosity determined by LIOAS and the local friction or microviscosity obtained from FA. Fil:Marchi, M.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Bilmes, S.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Negri, R.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07437463_v18_n18_p6730_Marchi http://hdl.handle.net/20.500.12110/paper_07437463_v18_n18_p6730_Marchi
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Excited states Anisotropy Chromophores Electron energy levels Fluorescence Gelation Hydrolysis Nanostructured materials Neutron scattering Nuclear magnetic resonance Percolation (fluids) Photoacoustic effect Raman spectroscopy Sol-gels
spellingShingle	Excited states Anisotropy Chromophores Electron energy levels Fluorescence Gelation Hydrolysis Nanostructured materials Neutron scattering Nuclear magnetic resonance Percolation (fluids) Photoacoustic effect Raman spectroscopy Sol-gels Marchi, María Claudia Aldabe Bilmes, Sara Alfonsina Dora Negri, Ricardo Martin Radiative and nonradiative excited state processes for studying the sol to gel evolution
topic_facet	Excited states Anisotropy Chromophores Electron energy levels Fluorescence Gelation Hydrolysis Nanostructured materials Neutron scattering Nuclear magnetic resonance Percolation (fluids) Photoacoustic effect Raman spectroscopy Sol-gels
description	The sol to gel evolution of systems based on the hydrolysis of titanium n-butoxide, Ti(OBu n ) 4 , in 1-butanol was investigated by monitoring the changes of the radiative and nonradiative electronic excited state processes of embedded dyes (cresyl violet and 4-(dicyanomethylene)-2-methyl-6(p-dimethylaminostyryl-4H-pyran). Fluorescence anisotropy experiments (FA) allow determination of changes in the microviscosity of the medium surrounding the fluorophore through the sol-gel evolution. The increase of the anisotropy parameter, 〈r〉, is explained in terms of solvent confinement in cavities enclosed within cross-linked polymeric chains. The acoustic signal recorded in laser-induced optoacoustics experiments (LIOAS) is attenuated as the system loses fluidity, with a minimum at t g , thus providing an alternative method for determining the gelation point. In addition, within the theoretical approach of percolation theory, the exponent of the viscosity power law is obtained from the attenuation of the sound wave. Although both FA and LIOAS provide information on the degree of cross-linking between polymeric chains, there is a clear difference between the behavior of the macroscopic shear viscosity determined by LIOAS and the local friction or microviscosity obtained from FA.
author	Marchi, María Claudia Aldabe Bilmes, Sara Alfonsina Dora Negri, Ricardo Martin
author_facet	Marchi, María Claudia Aldabe Bilmes, Sara Alfonsina Dora Negri, Ricardo Martin
author_sort	Marchi, María Claudia
title	Radiative and nonradiative excited state processes for studying the sol to gel evolution
title_short	Radiative and nonradiative excited state processes for studying the sol to gel evolution
title_full	Radiative and nonradiative excited state processes for studying the sol to gel evolution
title_fullStr	Radiative and nonradiative excited state processes for studying the sol to gel evolution
title_full_unstemmed	Radiative and nonradiative excited state processes for studying the sol to gel evolution
title_sort	radiative and nonradiative excited state processes for studying the sol to gel evolution
publishDate	2002
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_07437463_v18_n18_p6730_Marchi http://hdl.handle.net/20.500.12110/paper_07437463_v18_n18_p6730_Marchi
work_keys_str_mv	AT marchimariaclaudia radiativeandnonradiativeexcitedstateprocessesforstudyingthesoltogelevolution AT aldabebilmessaraalfonsinadora radiativeandnonradiativeexcitedstateprocessesforstudyingthesoltogelevolution AT negriricardomartin radiativeandnonradiativeexcitedstateprocessesforstudyingthesoltogelevolution
_version_	1768543472895131648

Radiative and nonradiative excited state processes for studying the sol to gel evolution

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