255 research outputs found
Copolymer-induced stabilizing effect of highly swollen hexagonal mesophases
We show quantitatively that tiny amounts of copolymer that decorate a
oil/water interfaces can greatly enhance the stability of swollen surfactant
hexagonal phases, comprising oil tubes regularly arranged in a water matrix.
Such soft composite materials, whose both radius of the tubes and water channel
between the tubes can be controlled independently over large ranges, offer a
potential interest for the synthesis of mesoporous materials
Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry
Mesoporous Aminopropyl-Functionalized Hybrid Thin Films with Modulable Surface and Environment-Responsive Behavior
Optical Properties of Au Nanoparticles Included in Mesoporous TiO<sub>2</sub> Thin Films: A Dual Experimental and Modeling Study
Gold
nanoparticles (NP) were synthesized inside ordered mesoporous
TiO<sub>2</sub> thin films (MTTF) by stepwise reduction of AuCl<sub>4</sub><sup>â</sup> with NaBH<sub>4</sub>. This leads to an
optical material (Au@TiO<sub>2</sub>) of interest for plasmonic applications.
The films (pure titania or gold-titania nanocomposites) were thoroughly
characterized by UVâvisible and ellipsometry spectroscopies.
The dielectric function of the MTTF, considered as the dielectric
environment in which the NP are embedded, was acquired by ellipsometry
and rationalized by the asymmetric Bruggeman model as an effective
medium formed by the mixture of dense TiO<sub>2</sub> and air. Nanocomposite
Au@TiO<sub>2</sub> systems present an isotropic dispersion of Au NP
in the 5â8 nm range. The UVâvisible spectra obtained
with a low nanoparticle filling fraction of the pore volume (<i>f</i><sub>NP</sub> < 2%) are accurately reproduced by both
MaxwellâGarnett (MG) and Mie theories. Accurate and coincident
values of <i>f</i><sub>NP</sub> and NP size are obtained
by this method. The dielectric function of Au NP used in this work
was studied in detail; in particular, the interface damping parameter
related to the NP/MTTF interface was determined by comparison with
TEM microscopy. The potential of the ellipsometry technique to determine
the material plasmonic response, and its correspondence with the UVâvisible
spectra, are discussed. This spectroscopy technique opens the possibility
to study the plasmon response of the material to changes in the environment
due to the presence of vapors, and other in situ experiments, as well
as to provide nanostructural information of metallic nanoparticles
(NP size, interparticle distance, number of NP) with well-defined
spatial localization in a multilayered system
Controlled Formation of Highly Organized Mesoporous Titania Thin Films: From Mesostructured Hybrids to Mesoporous Nanoanatase TiO 2
Time-Resolved Simultaneous Detection of Structural and Chemical Changes during Self-Assembly of Mesostructured Films
Evaporation-Induced Crystallization of Pluronic F127 Studied in Situ by Time-Resolved Infrared Spectroscopy
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