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Chimie de la Matière Condensée de Paris

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THEME I : MATERIALS WITH HIERARCHICAL STRUCTURE

 

ACTIVITY I : Elaboration of nanostructured and mesoporous films, micro-spheres, and patterns by Evaporation-Induced-Self-Assembly.

 

CORRESPONDING REVUES

 

A : Ultra low refractive index and dielectric constant coatings.

Nanocrystalline magnesium oxyfluoride films, bearing vesicle-like mesopores, have been prepared using an easy, surfactant free, CSD. The remarkable low refractive index (n=1.09 at 700nm) and dielectric constant (k = 1.6 at 100KHz) properties are attributed to the very high porosity created during decomposition of the perfluoroacetate ligands.

 

B : Inorganic/inorganic Nanostructured Patternings (INP).

Nanocrystalline Highly ordered Al2O3, TiO2 or ZrO2 nano-patternings have been deposited on Si, glass, ITO, or Au substrates using E.I.S.A. in presence of PS-PEO copolymers. Such novel nano-structured heterogeneous surfaces gather the properties of the pattern matrix and that of the substrate surface since the latter is accessible through the nano motifs.

 

C : Mesoporous (organically modified) silica optical coatings.

An EISA method leading to high quality mesoporous SiO2 thin films, exhibiting various structures (L, 2D-Hex, 3D-Hex, Cubic), porosities (20-60% vol and pore size 2-10 nm), thicknesses (20-1000nm), are reported. Ti, Zr, Al can be incorporated into the matrix, while the surface functionality can be adjusted by grafting o specific groups on the porosity surface.

D : Crystalline nanostructured oxide coatings

50 – 1000 nm thick, highly ordered mesoporous, optical films are prepared by combining the sol-gel chemistry, the EISA approach and CSDs processes. Crystallisation of the inorganic network (i.e. TiO2, Al2O3, ZrO2, SrTiO3, MgTa2O6, NiTiO3, HfO2…) is achieved without
mesostructure collapsing


 

E : Mesoporous nanocrystalline oxide spheres.

Aerosol generated E.I.S.A. titania, zirconia or alumina mesostructured micro-spheres have been prepared in presence of PEO-based block copolymers by atomisation. Crystallisation was achieved without  collapsing of the mesoporosity by a careful thermal treatment. The
mesoorder was found to play an important role in the involved kinetics.  

 

F : Multimodal mesoporous silica micro-spheres.

Aerosol generated E.I.S.A. silica mesostructured spheres are interesting materials for catalysis, drugg delivery, therapeutic vectoring, or in separation. Various structures (2DHex, cubic, hierarchical), porosities (from macro to micro) have been combined to design original multimodal objects.

 

ACTIVITY II : In situ time-resolved SAXS analyses of Self-Assembly Induced by Evaporation and crystallisation associated to mesoporous materials.

 

 

A : In situ simultaneous SAXS / Interferometry investigations of Evaporation-Induced-Self-Assembly during dip-coating.

The Austrian SAXS line (Elettra Synchrotron) was used to investigate self-assembly of sol-gel precursors (SiO2 and TiO2) with micelle templates during chemical solution deposition. Simultaneous interferometry analysis was conducted. This study revealed the complexity of the mechanism with the critical role of the atmosphere composition.

 

B : In situ simultaneous SAXS / WAXS investigations of mesoporous oxyde coating crystallisation during thermal treatment.

The Austrian SAXS/WAXS line (Elettra Synchrotron) was used to follow the crystallisation of metal oxide (TiO2, Al2O3, CeO2, SrTiO3…) mesoporous thin films during high temperature treatment. It revealed that crystallisation can be accompanied by a transformation into the grid-like structure and can be controlled so as to prevent collapsing of the mesostruture.

 

C : In situ  SAXS investigations of Evaporation-Induced-Self-Assembly during aerosol generation.

The Austrian SAXS line (Elettra Synchrotron) was used to investigate self-assembly of sol-gel precursors (SiO2 and TiO2) with micelle templates during aerosol generation of submicronic particles in air. It confirmed the critical role of the temperature of evaporation
that allows adjusting the water composition during EISA.

  • First in situ SAXS studies of the mesostructuration of spericalsilica and titania particles during spray-drying process. C. Boissière, D. Grosso, H. Amenitsch, A. Gibaud, A. Coupé, N. Bacille, C. Sanchez, Chem. Comm., 22 (2003) 2798.




ACTIVITY III : specific ellipsometric EEP and TEA analyses of thin films.

 

 

A : Environmental Ellipsometric Porosimetry (EEP)

In situ Spectroscopic Ellipsometry analysis of thin porous layers is used to measure the variation of refractive index and thickness during water chemisorption and condensation into the porosity. The resulting isotherms are then modelled to extract porosity, pore size distribution, homogeneity and transversal mechanical compressibility.

Analysis can be perform for external laboratory : see ATF

 

B : Thermal Ellipsometry Analysis (TEA)

In situ Spectroscopic Ellipsometry analysis of thin layers is used to measure the variation of refractive index and thickness during thermal treatment. The resulting evolutions are then used to assess phenomena such as densification, organic decomposition, crystallisation and
sintering. Kinetic parameters can be extracted from the plots. 

Analysis can be perform for external laboratory : see ATF

  • Pyrolysis, Crystallisation, and Sintering of Mesostructured Titania Thin Films Assessed by Thermal Ellipsometry, Bass J.D., Grosso D., Boissiere C. Sanchez C., Submitted.


 

ACTIVITY IV : Applications as fuel and photovoltaic cells, sensors, catalysis...

TiO2-based Photovoltaic cells and photocatalytic devices

 Mesoporous thin films as sensors

Mesoporous materials for catalysis

Biologically relevant applications