The objective of this thesis is to evaluate the molecular organization in hybrid mesoporous silica thin films obtained by evaporation-induced self-assembly. Various functional organic groups were introduced into the mesostructured films to observe their distribution and influence on the molecular self-assembly process. Three types of hybrid precursors with model structures were studied: I. Those with an alkyl chain (of different lengths and hydrophobicity) II. Those modified with a ureido moiety (self-assembly via hydrogen bonds and/or $\pi-\pi$ interactions) III. Those modified with pyrene (a fluorescent aromatic molecule forming an excimer complex that modifies its emission spectrum). Various characterization techniques were used to explore the structures at the nano and molecular scales: spectroscopies (IR, UV/Vis, Fluorescence, NMR), small-angle X-ray scattering, ellipsometry, and transmission electron microscopy.The results show very different results depending on the types of possible interactions. Alkyl chains induce a modification of the films' mesostructure by altering the curvature of the micelles. Film parameters, such as pore volume, pore size, and Young's modulus, vary under the influence of these molecules. The work demonstrated the existence of intramolecular interactions within the pores for systems containing ureido or pyrene functional groups. The results show the formation of hydrogen bonds, influencing the final structure, within the pores in the case of ureido groups. The formation of a pyrene excimer occurs only after the removal of the surfactant, confirming the localization of the molecules within the pores and the assembly mode depending on the respective concentrations of the precursors.This thesis illustrates the influence of the presence of organic functions in hybrid systems on the self-assembly and properties of mesoporous films, paving the way for new applications in materials science.
Gratuit
Disciplines