Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation

Detalhes bibliográficos
Autor(a) principal: Antunes, Filipe E.
Data de Publicação: 2007
Outros Autores: Brito, Rodrigo O., Marques, Eduardo F., Lindman, Björn, Miguel, Maria
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10316/10485
https://doi.org/10.1021/jp063994+
Resumo: Vesicles composed of an anionic and a cationic surfactant, with a net negative charge, associate strongly with a hydrophobically modified polycation (LM200) and with an unmodified polycation with higher charge density (JR400), forming viscoelastic gel-like structures. Calorimetric results show that in these gels, LM200 induces a rise of the chain melting temperature (Tm) of the vesicles, whereas JR400 has the opposite effect. For both polymer−vesicle systems, the shear viscosity exhibits an inflection point at Tm, and for the LM200 system the measured relaxation times are significantly higher below Tm. The neat vesicles and the polycation-bound vesicles have a polygonal-like faceted shape when the surfactant chains in the bilayer are crystallized, as probed by cryo-transmission electron microscopy. Above Tm, the neat and the LM200-bound vesicles regain a spheroidal shape, whereas those in the JR400 system remain with a deformed faceted shape even above Tm. These shape changes are interpreted in terms of different mechanisms for the polymer−vesicle interaction, which seem to be highly dependent on polymer architecture, namely charge density and hydrophobic modification. A crystallization−segregation mechanism is proposed for the LM200−vesicle system, while, for the JR400−vesicle one, charge polarization−lateral segregation effects induced by the polycation in the catanionic bilayer are envisaged.
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spelling Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and SegregationVesicles composed of an anionic and a cationic surfactant, with a net negative charge, associate strongly with a hydrophobically modified polycation (LM200) and with an unmodified polycation with higher charge density (JR400), forming viscoelastic gel-like structures. Calorimetric results show that in these gels, LM200 induces a rise of the chain melting temperature (Tm) of the vesicles, whereas JR400 has the opposite effect. For both polymer−vesicle systems, the shear viscosity exhibits an inflection point at Tm, and for the LM200 system the measured relaxation times are significantly higher below Tm. The neat vesicles and the polycation-bound vesicles have a polygonal-like faceted shape when the surfactant chains in the bilayer are crystallized, as probed by cryo-transmission electron microscopy. Above Tm, the neat and the LM200-bound vesicles regain a spheroidal shape, whereas those in the JR400 system remain with a deformed faceted shape even above Tm. These shape changes are interpreted in terms of different mechanisms for the polymer−vesicle interaction, which seem to be highly dependent on polymer architecture, namely charge density and hydrophobic modification. A crystallization−segregation mechanism is proposed for the LM200−vesicle system, while, for the JR400−vesicle one, charge polarization−lateral segregation effects induced by the polycation in the catanionic bilayer are envisaged.American Chemical Society2007-01-11info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10316/10485http://hdl.handle.net/10316/10485https://doi.org/10.1021/jp063994+engThe Journal of Physical Chemistry B. 111:1 (2007) 116-1231520-6106Antunes, Filipe E.Brito, Rodrigo O.Marques, Eduardo F.Lindman, BjörnMiguel, Mariainfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2020-03-06T10:13:39Zoai:estudogeral.uc.pt:10316/10485Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T21:01:32.486398Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
title Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
spellingShingle Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
Antunes, Filipe E.
title_short Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
title_full Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
title_fullStr Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
title_full_unstemmed Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
title_sort Mechanisms behind the Faceting of Catanionic Vesicles by Polycations: Chain Crystallization and Segregation
author Antunes, Filipe E.
author_facet Antunes, Filipe E.
Brito, Rodrigo O.
Marques, Eduardo F.
Lindman, Björn
Miguel, Maria
author_role author
author2 Brito, Rodrigo O.
Marques, Eduardo F.
Lindman, Björn
Miguel, Maria
author2_role author
author
author
author
dc.contributor.author.fl_str_mv Antunes, Filipe E.
Brito, Rodrigo O.
Marques, Eduardo F.
Lindman, Björn
Miguel, Maria
description Vesicles composed of an anionic and a cationic surfactant, with a net negative charge, associate strongly with a hydrophobically modified polycation (LM200) and with an unmodified polycation with higher charge density (JR400), forming viscoelastic gel-like structures. Calorimetric results show that in these gels, LM200 induces a rise of the chain melting temperature (Tm) of the vesicles, whereas JR400 has the opposite effect. For both polymer−vesicle systems, the shear viscosity exhibits an inflection point at Tm, and for the LM200 system the measured relaxation times are significantly higher below Tm. The neat vesicles and the polycation-bound vesicles have a polygonal-like faceted shape when the surfactant chains in the bilayer are crystallized, as probed by cryo-transmission electron microscopy. Above Tm, the neat and the LM200-bound vesicles regain a spheroidal shape, whereas those in the JR400 system remain with a deformed faceted shape even above Tm. These shape changes are interpreted in terms of different mechanisms for the polymer−vesicle interaction, which seem to be highly dependent on polymer architecture, namely charge density and hydrophobic modification. A crystallization−segregation mechanism is proposed for the LM200−vesicle system, while, for the JR400−vesicle one, charge polarization−lateral segregation effects induced by the polycation in the catanionic bilayer are envisaged.
publishDate 2007
dc.date.none.fl_str_mv 2007-01-11
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10316/10485
http://hdl.handle.net/10316/10485
https://doi.org/10.1021/jp063994+
url http://hdl.handle.net/10316/10485
https://doi.org/10.1021/jp063994+
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv The Journal of Physical Chemistry B. 111:1 (2007) 116-123
1520-6106
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dc.publisher.none.fl_str_mv American Chemical Society
publisher.none.fl_str_mv American Chemical Society
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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