Cargando…
Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase
Due to the characteristic chain rigidity and weak intermolecular interactions of perfluorinated substances, the phase diagram of Langmuir monolayer formed by perfluorinated molecules has been interpreted so far as displaying only two phases, a 2D gas (G) and a liquid condensed (LC). However, in this...
Autores principales: | , , , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2019
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804139/ https://www.ncbi.nlm.nih.gov/pubmed/31590402 http://dx.doi.org/10.3390/molecules24193590 |
_version_ | 1783461113910788096 |
---|---|
author | Fontaine, Philippe Filipe, Eduardo J. M. Fauré, Marie-Claude Rego, Tomas Taßler, Stephanie Alves, Ana Carolina Silva, Gonçalo M. C. Morgado, Pedro Goldmann, Michel |
author_facet | Fontaine, Philippe Filipe, Eduardo J. M. Fauré, Marie-Claude Rego, Tomas Taßler, Stephanie Alves, Ana Carolina Silva, Gonçalo M. C. Morgado, Pedro Goldmann, Michel |
author_sort | Fontaine, Philippe |
collection | PubMed |
description | Due to the characteristic chain rigidity and weak intermolecular interactions of perfluorinated substances, the phase diagram of Langmuir monolayer formed by perfluorinated molecules has been interpreted so far as displaying only two phases, a 2D gas (G) and a liquid condensed (LC). However, in this work, we presented Grazing Incidence X-ray Diffraction measurements, which exhibit two diffraction peaks on the transition plateau: One is the signature of the hexagonal structure of the LC phase, the second one is associated to the low-density fluid phase and is thus more ordered than expected for a 2D gas or a typical fluid phase. Atomistic molecular dynamics simulations, performed on the transition plateau, revealed the existence of clusters in which domains of vertical molecules organized in a hexagonal lattice coexist with domains of parallel lines formed by tilted molecules, a new structure that could be described as a “2D smectic C” phase. Moreover, the diffraction spectrum calculated from the simulation trajectories compared favorably with the experimental spectra, fully validating the simulations and the proposed interpretation. The results were also in agreement with the thermodynamic analysis of the fluid phase and X-ray Reflectivity experiments performed before and after the transition between these two phases. |
format | Online Article Text |
id | pubmed-6804139 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-68041392019-11-18 Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase Fontaine, Philippe Filipe, Eduardo J. M. Fauré, Marie-Claude Rego, Tomas Taßler, Stephanie Alves, Ana Carolina Silva, Gonçalo M. C. Morgado, Pedro Goldmann, Michel Molecules Article Due to the characteristic chain rigidity and weak intermolecular interactions of perfluorinated substances, the phase diagram of Langmuir monolayer formed by perfluorinated molecules has been interpreted so far as displaying only two phases, a 2D gas (G) and a liquid condensed (LC). However, in this work, we presented Grazing Incidence X-ray Diffraction measurements, which exhibit two diffraction peaks on the transition plateau: One is the signature of the hexagonal structure of the LC phase, the second one is associated to the low-density fluid phase and is thus more ordered than expected for a 2D gas or a typical fluid phase. Atomistic molecular dynamics simulations, performed on the transition plateau, revealed the existence of clusters in which domains of vertical molecules organized in a hexagonal lattice coexist with domains of parallel lines formed by tilted molecules, a new structure that could be described as a “2D smectic C” phase. Moreover, the diffraction spectrum calculated from the simulation trajectories compared favorably with the experimental spectra, fully validating the simulations and the proposed interpretation. The results were also in agreement with the thermodynamic analysis of the fluid phase and X-ray Reflectivity experiments performed before and after the transition between these two phases. MDPI 2019-10-05 /pmc/articles/PMC6804139/ /pubmed/31590402 http://dx.doi.org/10.3390/molecules24193590 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Fontaine, Philippe Filipe, Eduardo J. M. Fauré, Marie-Claude Rego, Tomas Taßler, Stephanie Alves, Ana Carolina Silva, Gonçalo M. C. Morgado, Pedro Goldmann, Michel Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title | Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title_full | Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title_fullStr | Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title_full_unstemmed | Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title_short | Structure of Langmuir Monolayers of Perfluorinated Fatty Acids: Evidence of a New 2D Smectic C Phase |
title_sort | structure of langmuir monolayers of perfluorinated fatty acids: evidence of a new 2d smectic c phase |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804139/ https://www.ncbi.nlm.nih.gov/pubmed/31590402 http://dx.doi.org/10.3390/molecules24193590 |
work_keys_str_mv | AT fontainephilippe structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT filipeeduardojm structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT fauremarieclaude structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT regotomas structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT taßlerstephanie structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT alvesanacarolina structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT silvagoncalomc structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT morgadopedro structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase AT goldmannmichel structureoflangmuirmonolayersofperfluorinatedfattyacidsevidenceofanew2dsmecticcphase |