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In situ characterisation of a growing surfactant-templated silica film has been carried out by X-ray reflectivity, diffuse X-ray scattering from the surface. Brewster angle microscopy and surface pressure measurements. The results indicate an unexpected film growth mechanism where layered structures form in solution and diffuse to the interface after some critical induction period.
A facile in situ nanoparticle seeding method is reported to prepare MIL-101(Cr) films on alumina supports. The in situ seeding of MIL-101(Cr) nanoparticles was promoted by use of dimethylacetamide (DMA). The generality of this approach is further demonstrated for Cu3(btc)2 films by using a (poly)acrylate promoter.
Off-specular X-ray reflectivity measurements were carried out to follow the in situ development of surfactant-templated silica thin films at the air-water interface under conditions of controlled relative humidity and temperature, using an enclosed sample cell designed for this purpose. The results suggest a strong dependence of formation time and growth mechanism on ambient conditions. Thin films
Colloidal ZnO is obtained during microwave-enhanced electrochemical deposition experiments from an aqueous solution containing 0.1 M Zn(NO 3)2 and 0.02 M H2O2 via repetitive negative going potential cycles from 0.3 to -0.8 V vs. SCE. The effects of temperature and temperature gradients on ZnO electro-formation at fluorine doped tin oxide (FTO) electrodes are investigated with both a conventional t
We have investigated the spontaneous self-assembly of solid, mesostructured films that form at the air-solution interface on solutions containing a neutral water-soluble polymer and catanionic surfactant mixtures of hexadecyl-trimethylammonium bromide (CTAB) and sodium dodecylsulphate (SDS). The formation processes and structures were probed using neutron reflectivity, X-ray reflectivity, off-spec
Micron-thick hydrogel films with ordered 3D mesostructures form spontaneously at the interface of polyelectrolyte-surfactant solutions. Here we demonstrate that by rationally designing the micelle shapes it is possible to predict and so tailor the nanostructure formed within surfactant-polyelectrolyte films. Using quaternary ammonium surfactants with a range of packing parameters, we demonstrate t
The mechanisms of entrapment, and the nanoscopic spatial distribution, of the residual mercury within nano-cast and amorphous porous media (pore sizes ∼1-100 nm) following high-pressure penetration have been studied. It has been shown that, even at the nanoscale, one of the same two principle mechanisms that have been observed previously in mercury porosimetry experiments on macroscopic glass pore
Highly structured catalyst support pellets have been produced that possess multiple, but regiospecific and well-defined, pore geometries. Mesoporous silica pellets with controlled pore sizes have been synthesised using one type of pore template for the pellet core zone, whilst using a different type of template for the surrounding shell region. These materials offer the potential of adding precise
Chemically surface-modified (tosyl-functionalized) carbon nanoparticles (Emperor 2000 from Cabot Corp.) are employed for the extraction and electrochemical determination of phenolic impurities such as benzophenone-3 (2-hydroxy-4-methoxybenzophenone) or triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol). The hydrophilic carbon nanoparticles are readily suspended and separated by centrifugation prio
The synthesis of surfactant-templated silicate materials has developed rapidly over the past decade. The uniform controlled pore sizes created in the amorphous silicate framework by this method show promise as catalyst supports, sensors, filtration membranes and in a variety of optoelectronic applications. Formation of these materials in a thin-film or membrane geometry is therefore an active area
Orientational ordering under shear was observed for some precursor gels for the synthesis of the hexagonal mesoporous silica MCM-41 in the presence of high KBr concentrations. The presence of KBr disrupted the formation of the first-order MCM-41 diffraction peak dependent upon KBr concentration. Synthesis gels which formed good quality MCM-41, but with no added KBr salt, were not oriented by stron
Adsorption isotherms taken at temperatures ranging from 20 to 77 K show a large pore volume and surface area of 980 m2 g-1 for the physical adsorption of molecular hydrogen on MCM-41. The adsorbed hydrogen behaves more like a solid than a liquid and isosteric heats of adsorption reveal a heterogenous surface. The evaporation behaviour of the adsorbed hydrogen indicates that the hexagonally packed
"Simple" silica films of 50nm and 100nm thickness are sputter-coated onto ITO substrates and shown to be structured with in-planed features of ca. 15nm and pores <5nm (based on GISAXS). In electrochemical measurements membrane pore effects are observed. The oxidation current for Fe(CN)64- in aqueous KNO3 strongly depends on the electrolyte concentration. Poly-cationic poly(diallyl-dimethylammonium
The formation of surfactant templated silica films at the air-solution interface has been investigated in situ using a number of time-resolved surface-sensitive and bulk sensitive techniques. Results from templating solutions prepared using a non-ionic surfactant (C16EO8) are compared to those obtained when a cationic surfactant (CTAB) is used. In both cases specific solution phase interactions dr
The measurement of adsorption of cytochromes c onto the external surfaces of a thin film mesoporous silicates (MPS) supported by silicon wafers was discussed. Adsorption in a multilayered system consisting silicon, SiO 2, MPS, and adsorbed proteins was analyzed using ellipsometry. Synthesis of MPS thin films on 0.5 mm thick silicon wafers was done using a dip-coating alcohol vaporization method. I
Mesoporous silica vesicles (MSV) with a hierarchical structure were developed using triblock copolymer Pluronic P103 and anionic surfactant sodium dodecyl sulfate (SDS) as a co-surfactant in the present of an inorganic salt, sodium fluoride (NaF). To some extent, variation in the particle size and vesicle cavity diameter can be achieved by adjusting the anionic-nonionic surfactant molar ratio. An
A strategy for the formation of thin reconstituted cellulose films (pure or modified)) with embedded receptors or embedded ion-selective components is reported. Cellulose nanofibril ribbons from sisal of typically 3-5 nm diameter and 250 nm length are reconstituted into thin films of typically 1.5-2.0 μm thickness (or into thicker free-standing films). Cellulose and cellulose nanocomposite films a
Surfactant-templated polymer films prepared from polyethylenimine (PEI), cetyltrimethylammonium bromide (CTAB), and octaethylene glycol monohexadecyl ether (C16E8) were examined and the effect of increasing the percentage of nonionic surfactant in the micelles measured using both surface and bulk-sensitive techniques. It was found that there is a strong interaction between CTAB and C16E8, although
Keggin tungstophosphoric acid supported onto mesoporous and meso-microporous materials was studied by ammonia microcalorimetry. Experiments were performed at high and low temperatures to separate the contributions of chemisorpdon and physisorption, low-temperature data being potentially important for the ambient temperature purification processes. Analysis of thermokinetic data obtained from heat
There has been little, or no, direct testing of theories of gas sorption within particular pores situated amidst a highly inter-connected pore network. The concept of thermodynamically independent pores within networks has also been challenged. In this work, a novel integrated nitrogen sorption and mercury porosimetry technique has been used to deconvolve the condensation and evaporation processes
