The formation of hexagonal and lamellar surfactant−silicate mesophases at room temperature has been investigated by in situ synchrotron small angle X-ray scattering. Emphasis was given to the influence of butanol and hexanol on the surfactant−silicate phase behavior. The experimental setup included a continuous flow reactor allowing a resolution in time as high as 0.3 s. Depending on the reaction composition, one, two, or three coexisting phases were observed. The results are discussed in terms of time-dependent changes in the concentration of cosurfactant not incorporated into the composite aggregates. Although many of the observed effects are paralleled by well-known properties of aqueous surfactant solutions, important dissimilarities exist. Furthermore, the relative intensity of the high-order reflections are suggested to correspond to the degree of interaggregate condensation in the composite mesophas

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Immobilization of gold nanoparticles on planar surfaces is of great interest to many scientific communities; chemists, physicists, biologists, and the various communities working at the interfaces between these disciplines. Controlling the immobilization step, especially nanoparticles dispersion and coverage, is an important issue for all of these communities. We studied the parameters that can influence this interaction, starting with the nature of the terminal chemical function. Thus, we have carefully grafted silanes terminated by either amine or thiol groups starting from aminopropyltriethoxysilane (APTES) or mercaptopropyltriethoxysilane. We also changed the chain length for thiol-terminated layers through covalent grafting of mercaptoundecanoic acid (MUA) on APTESmodified layers, and the protocol of nanoparticles deposition to evaluate whether other factors must be taken into consideration to rationalize this interaction. The formed layers were characterized by X-ray photoelectron spectroscopy and gold nanoparticles deposition was monitored by scanning electron microscopy and surface-enhanced Raman scattering. We observed significant differences in terms of nanoparticles dispersion and density depending on the nature of the chemical layer on silicon. The use of ultrasounds during the deposition process was very efficient to limit aggregates formation. The optimal deposition procedures were obtained through the use of APTES and APTES/MUA functionalization. They were compared in terms of coverage, dispersion, and densities of isolated nanoparticles. The APTES/MUA surfaces clearly showed better results that may arise from both the longer chain and the dilution of thiol end groups.

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The phase behavior of Zr(SO 4 ) 2 /CTAB composite mesophases was investigated as a function of surfactant chain length, temperature, and salt concentration by XRD. It was shown that the initial step is a rapid formation of either a pure lamellar, hexagonal, or a mixed hexagonal/ lamellar phase with a low degree of condensation (room temperature), depending on the chain length of the surfactant as well as on the ionic strength of the solution. The observed features may be qualitatively explained by expected variations in the packing parameter. TiOSO 4 /CTAB composite mesophases were shown to form in a similar manner as Zr(SO 4 ) 2 / CTAB. A model accounting for changes in the inorganic framework with increasing degree of intraaggregate condensation was developed. Furthermore, using a tubular reactor setup connected to an in situ XRD cell it was shown that the mesophase formation occurred immediately (<300 ms) after mixing of the reagents, which is the fastest ever recorded composite mesophase formation.

Several series of metal-acid bifunctional catalysts with controlled metal:acid ratios and metal site-acid site proximity were evaluated for n-heptane isomerization. Through the study of metal deposition reported in the companion paper, proximity could be achieved at four distinct scales; atomic, nano-, micro-, and millimeter scales. In the first two catalyst series, atomic and nanometer scale intimacy was obtained by depositing Pt onto acidic silica-alumina supports (Pt/Al-Si). It is demonstrated that poorly dispersed Pt/silica-alumina catalysts with nanometerscale proximity displayed a greater degree of bifunctionality than highly dispersed catalysts with atomic-scale proximity. In the latter two series of catalysts the scale of intimacy was stretched to micrometers using physical mixtures, and to millimeters by separating layers of nonacidic Pt/silica and metal free silica-alumina. Good bifunctionality is maintained at micrometer-scale intimacy and breaks down only at the millimeter scale. The best bifunctionality is achieved at very high acid to metal site ratios; results indicated that a single metal site can supply several hundred acid sites. Optimized bifunctional performance of Pt/silica-alumina catalysts for n-heptane isomerization requires a high acid-to-metal site ratio with nanometer to micrometer scale site proximity. The control of the numbers and proximities of metal and acid sites achieved in this work can be extended to many other metal-acid bifunctional reactions.

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