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Associations macromoléculaires en solution et aux interfaces : stimulation et ciblage par le pH et la température

Abstract : We are investigating the assembling properties of responsive polymers in bulk and at interfaces. The assembling properties are tuned with temperature and pH by using complementary units. Associations are induced by a lower critical solution temperature (LCST) type phase separation taking place at a local scale. Introducing weak acid or base units in thermoassociative copolymers leads to pH-sensitive polymers. Two different random copolymers are obtained: one including weak acid units (Acrylic Acid (AA)), the other one including weak base comonomers (N,N - [(dimethylamino) propyl] methacrylamide (MADAP)). While all ionized copolymers remain soluble in water at all temperatures, their mixtures show a phase separation above a critical temperature due to the formation of a reversible inter-polyelectrolyte complex. When the responsive stickers are grafted on a poly(acrylamide) backbone, pH and temperature are still able to drive the association process at a local scale, giving rise to a sol/gel transition of semi-dilute solutions. The structure and the viscoelastic properties of these macromolecular assemblies are investigated by small angle neutron scattering and rheology. The environmental parameters (pH, temperature, ionic strength) and the addition of stickers with opposite charge can trigger specific association. In an original way, knowledge from associative properties in bulk is applied to interfaces to study adaptive surfaces. Specific interactions between polymer brushes and macromolecular solutions are characterized by ellipsometry and neutron reflectivity. We show that the adsorption of free grafts and comb copolymers on homopolymer brushes is controlled by environmental conditions (pH and temperature) and is completely reversible.
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https://pastel.archives-ouvertes.fr/pastel-00584947
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Submitted on : Monday, April 11, 2011 - 2:01:20 PM
Last modification on : Wednesday, October 14, 2020 - 3:43:23 AM
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  • HAL Id : pastel-00584947, version 1

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Elodie Siband. Associations macromoléculaires en solution et aux interfaces : stimulation et ciblage par le pH et la température. Polymères. Université Pierre et Marie Curie - Paris VI, 2009. Français. ⟨pastel-00584947⟩

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