In this work we have explored the possibility of using surfactant/polyelectrolyte complexes as templates to synthesize inorganic mesostructured materials mainly with a film morphology. Inorganic species deposit in those regions of the films which are filled with a polymer hydrogel, surrounding the arrays of ordered surfactant micelles. This method produced thick robust films where the inorganic regions are reinforced and functionalized by the polymer, thus these materials are expected to have potential applications in separation, absorption, catalysis and chemical sensing.
Initial work involved mixing silicate precursors directly into CTAB/PEI solutions to form highly ordered 2D hexagonal silica films at the air/water interface. Time resolved synchrotron SAXS allowed investigation of processes occurring in solution during the reaction, from which a film growth mechanism was proposed. Films had good thermal properties and after post-synthesis TMOS vapour treatment, retained structure upon template removal. Silica gel monoliths with various mesostructures were also rapidly fabricated in one minute with surfactant/LPEI complexes.
Cat-ionic surfactant mixtures with polymers were also employed to template silica films with different cubic mesostructures at the air/water interface. The mesophases of the interfacial films were enriched due to more complicated interactions between the polymers and two surfactants. Polymer molecular weight, total composite concentration, chemical nature of the polymer as well as the cationic-anionic surfactant molar ratio was used to systematically control the silica film mesophase.
Robust titania films were also prepared with cat-anionic surfactant mixtures and polymers at the air/water interface. Although the film mesostructure was lost after calcination, the in-situ and dry free-standing films display ordered cubic mesostructures and the films are stable to calcination after post-synthesis treatment. Ordered lamellar iron oxide films templated by SDS/LPEI complexes were also prepared at the air/water interface.
|Date of Award||1 Sep 2010|
|Supervisor||Karen Edler (Supervisor)|