Etude des films de Langmuir de copolymères diblocs et formation de nanostructures inorganiques par réduction des ions argent à leur voisinage.

Abstract : We studied the copolymer PS-b-PAA Langmuir films and the formation of non-organic nanostructures by reduction of silver ions Ag+ in their neighborhood. On the one hand, we have precisely determined the structure of these copolymers at the air-water interface for different pH with many complementary techniques (isothermal, π-A, neutron reflectivity, grazing-incidence x-ray scattering). This study proved that the classic interpretation of these isotherms should be reconsidered and we emphasized the major role played by the spreading solvent. This (solvent) is partially absorbed by the surface after the deposit and the mixed copolymer-solvent monolayer is created by the surface nanostructure. These nanostructures have a well-defined typical size. When the PAA chains are neutral, the pseudo-surface observed on the isotherms corresponds to the reversible expulsion of the solvent to a subphase which induces a reorganization of the nanostructures. In the case of charged PPA chains, the isotherm does not show the flat surface. This is due to the electrostatic repulsion between these chains. The compression of the film induces the «dive» of a part of the monolayer – copolymer and solvent – towards the volume. On the other hand, we studied the behavior of these charged copolymer films in the presence of silver ions Ag+ in the before and after reduction. We showed that the presence of Ag+ ions induces the collapse of the PAA chains at the interface. The ions reduction by surface x-rays radiolysis produces silver colloids following a «bi-continuous» 2D structure with a typical length scale. However, the photo-chemical reduction does not seem to produce homogenous and dense layers of colloids.
Document type :
Theses
Complete list of metadatas

Cited literature [118 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-01097435
Contributor : Zineb Guennouni <>
Submitted on : Friday, December 19, 2014 - 4:05:28 PM
Last modification on : Friday, May 24, 2019 - 5:25:07 PM
Long-term archiving on: Monday, March 23, 2015 - 6:28:47 PM

Identifiers

  • HAL Id : tel-01097435, version 1

Citation

Zineb Guennouni. Etude des films de Langmuir de copolymères diblocs et formation de nanostructures inorganiques par réduction des ions argent à leur voisinage.. Physique [physics]. Université Pierre et Marie Curie, 2014. Français. ⟨tel-01097435⟩

Share

Metrics

Record views

616

Files downloads

572