1. Coupled Effects of Spreading Solvent Molecules and Electrostatic Repulsions on the Behavior of PS-b-PAA Monolayers at the Air–Water Interface
- Author
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Patrick Perrin, Fabrice Cousin, Philippe Fontaine, Denis Limagne, Michel Goldmann, Zineb Guennouni, Marie-Claude Fauré, Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Léon Brillouin (LLB - UMR 12), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Physico-chimie et dynamique des surfaces (INSP-E6), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Paris Descartes - Faculté des Sciences Fondamentales et Biomédicales (UPD5 Sciences), Université Paris Descartes - Paris 5 (UPD5), Sciences et Ingénierie de la Matière Molle (SIMM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut des Nanosciences de Paris ( INSP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Léon Brillouin ( LLB - UMR 12 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris-Saclay, Synchrotron SOLEIL ( SSOLEIL ), Centre National de la Recherche Scientifique ( CNRS ), Physico-chimie et dynamique des surfaces ( INSP-E6 ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Université Paris Descartes - Faculté des Sciences Fondamentales et Biomédicales ( UPD5 Sciences ), Université Paris Descartes - Paris 5 ( UPD5 ), Sciences et Ingénierie de la Matière Molle ( SIMM ), Centre National de la Recherche Scientifique ( CNRS ) -PSL Research University ( PSL ) -ESPCI ParisTech-Université Pierre et Marie Curie - Paris 6 ( UPMC ), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay, Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Centre National de la Recherche Scientifique (CNRS)-PSL Research University (PSL)-ESPCI ParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)
- Subjects
Langmuir ,Chemistry ,Scattering ,Spinodal decomposition ,Analytical chemistry ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surface pressure ,[ CHIM ] Chemical Sciences ,01 natural sciences ,0104 chemical sciences ,Solvent ,Monolayer ,Electrochemistry ,[CHIM]Chemical Sciences ,Grazing-incidence small-angle scattering ,Molecule ,General Materials Science ,0210 nano-technology ,Spectroscopy - Abstract
International audience; We describe the surface behavior of PS-b-PAA monolayers at the air/water interface using N,N-dimethyformamide (DMF) as spreading solvent. At low pH, when the PAA blocks are neutral, the surface pressure versus molecular area isotherm shows a pseudoplateau associated with the presence of remaining solvent spreading molecules in the monolayer, as we described in a former study (Guennouni et al, Langmuir, 2016). We show here that the width of the plateau decreases when increasing pH up to its complete disappearance at high pH, when PAA blocks are fully charged, although there still exist two regimes of compressibilities on the isotherm. A refined structural study at pH 9 combining Specular Neutron Reflectivity (SNR), Grazing-Incidence Small-Angle X-rays Scattering (GISAXS) and Atomic Force Microscopy (AFM) in liquid measurements show that: (i) PAA blocks are stretched in solution, as expected from polyelectrolyte brushes in osmotic regime; (ii) the system undergoes a spinodal decomposition during deposit at the air/water interface in presence of DMF. Upon compression, the Qxy* position of the peak associated with the spinodal structure remains almost constant but its intensity evolves strongly and passes through a maximum at intermediate pressures. This reveals two operating processes in the system: strong electrostatic repulsions between chains that prevent in-plane reorganizations and force such reorganizations to occur from the surface to the volume and progressive expulsion of the DMF molecules from the monolayer. These processes have antagonist effects on the intensity of the peak: the increase of the repulsions makes it more pronounced whereas the expulsion of solvent makes it vanish due to the loss of contrast.
- Published
- 2017