Filtyp
A pure silica MCM-41 preparation with high crystalline order perpendicular to the channels has been examined using small-angle neutron scattering and the contrast variation method in both the calcined and template-containing forms. This defines various structural features such as template and water distributions and content, local silica density, and surface properties. Adsorption isotherm data, N
We have previously reported that robust mesostructured films will grow at the surface of alkaline solutions containing cetyltrimethylammonium bromide (CTAB), polyethylenimine (PEI), and silica precursors. Here we have used time-resolved small-angle X-ray scattering to investigate the structural evolution of the micellar solution from which the films form, at several different CTAB-PEI concentratio
Dilute mixtures of the water soluble polymer polyethyleneimine (PEI) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) form mesostructured thin films at the air/solution interface. In this paper we show that these films form spontaneously, reaching an equilibrium composition. When the film is removed, a new solid film rapidly reforms, with a similar morphology when inspected by Bre
Nanoparticle film voltammetry is employed to explore the presence and reactivity of surface-stabilised iron redox centers at the interface of immobilised Fe2O3 nanoparticles of ca. 4 nm diameter and aqueous buffer media. Mesoporous films of Fe2O3 nanoparticles on tin-doped indium oxide (ITO) substrates are formed in a layer-by-layer deposition process from aqueous colloidal Fe2O3 and aqueous cyclo
In order to rationally design polymer vehicles for controlled drug delivery it is important to completely understand the nature and mechanisms of the structural evolution of the polymer matrix that ultimately controls drug release kinetics. NMR cryoporometry has been used previously to study drug release from polymer vehicles. However, no previous studies have employed the integrated cryoporometry
We have prepared and analyzed thin film structures formed by polyethylenimine and alkyltrimethylammonium bromide (CnTAB) surfactants at the air/water interface, using both surface and bulk sensitive techniques. In initial experiments it was observed that hexagonal arrays of rodlike micelles surrounded by the polymer were formed at the solution surface, with the principal axis of the micelles runni
Cellulose nanofibrils from sisal of typically 4-5 nm diameter and ca. 250 ± 100 nm length are reconstituted into thin films of ca. 6 m thickness (or thicker freestanding films). Pure cellulose and cellulose composite films are obtained in a solvent evaporation process. A boronic acid appended dendrimer is embedded as a receptor in the nanofibrillar cellulose membrane. The number of boronic acid bi
A dilute mixed-surfactant solution to synthesize mesoporous silver films by using a dip-coating method was used for the creation of films over a large area of substrate. The method allows facile creation of films over a large area of substrate, unlike electrochemical deposition, and uses smaller amounts of surfactant than typical LLC syntheses. The silver ions in the solution, deposited in the int
We have examined the effect of the different components in the spontaneous formation of surfactant-templated mesostructured silicate films grown at the air/solution interface. The rate of film formation shows differing dependencies on the concentrations of the silica precursor, tetramethoxysilane, the surfactant template, cetyltrimethylammonium bromide (CTAB), water and the solution pH. Further, w
Grazing incidence X-ray diffraction (GIKD) and X-ray reflectivity have been used in situ to study the structure of surfactant-templated silica films grown at the air/water interface at different depths in the film. The results confirm that cylindrical silica-encased surfactant micelles are predominantly organized into a two-dimensional hexagonal structure, with the long axis parallel to the surfac
Self-assembly processes and corresponding phase boundaries depend on the structure of interacting molecules. We have studied the effect of surfactant head-group structure and counterion on the self-assembly processes occurring in aqueous mixtures of the cationic polymer polyethylenimine (PEI) and the cationic surfactants cetyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and cety
The functionalised metal-organic framework MIL-101(Cr)-NH2, containing 2-aminobenzene-1,4-dicarboxylate as the linker, has been synthesised. A new tandem post-synthetic modification strategy involving diazotisation as the first step has been developed and used to introduce halo- and azo dye-functional groups into the pores.
A novel way to produce ultrathin transparent carbon layers on tin-doped indium oxide (ITO) substrates is developed. The ITO surface is coated with cellulose nanofibrils (from sisal) via layer-by-layer electrostatic binding with poly(diallyldimethylammonium chloride) or PDDAC acting as the binder. The cellulose nanofibril-PDDAC composite film is then vacuum-carbonised at 5008C. The resulting carbon
A new type of surfactant templated polymer film, which spontaneously forms at the air/water interface into micron-thick structures, was prepared from a water-soluble polymer and a catanionic surfactant mixture; the film is stable, highly ordered and robust, requiring no cross-linking agents to fix the structure.
Mesoporous titanium dioxide films have been produced via a self assembly pathway at the air-ethanol interface using partially fluorinated surfactants as structure directing agents. The high level of surface activity displayed by partially fluorinated compounds in alcohols has been used to generate an ordered film at the air-solution interface, as titanium oligomers condense into an ordered inorgan
The first series of carbosilane liquid crystal codendrimers with groups of different polarity has been synthesized. The chemical structure of the newly synthesized materials and the composition of the codendrimers were studied by NMR spectroscopy and MALDI-TOF MS. It was found that the codendrimers tend to form stable Langmuir films at the air-water surface. The influence of composition and genera
Time-resolved small-angle neutron scattering has been used to investigate the evolution of micelles in the subphase of surfactant-templated silica film-forming solutions. Two samples have been prepared using cetyltrimethylammonium bromide (CTABr), as the structure-directing agent, and different amounts of tetramethoxysilane (TMOS) (CTABr/TMOS molar ratio 0.093, 0.139). The solutions have been repr
Synchrotron X-ray diffraction patterns for highly crystalline MCM-41 a mesoporous silicate molecular sieve are presented. The form factor observed in seven orders of diffraction is used to show the existence of a two-layer wall structure, with a narrower mesopore than previously assumed, and much void space in the walls.
Two CTABr-silica mesophases have been prepared, one of them as a powder with hexagonal structure containing Congo Red, the other one as a film with cubic structure containing Disperse Red 1. In the former case the dye has been occluded via co-entrapping, whereas in the latter it has been covalently anchored to the silica matrix via a co-condensation route. In both systems, the dye molecules proved
