Sol-gel templating of membranes to form thick, porous titania, titania/zirconia and titania/silica films

摘要

Cellulose acetate, cellulose nitrate, polyamide, polyethersulfone and polypropylene membranes have been used as templates in which sol-gel chemistry was conducted to fabricate porous metal oxide films. Dilution of the metal alkoxide solution allowed for variation in the total amount of inorganic deposited per membrane. Multiple coatings with dilute precursor gave control of the final wall thickness. The correlation between the morphology of the metal oxide and the various structures of the membrane templates indicates the concise coating of the organic material during the templating process. Substantial variation in structure and characteristic properties of the membranes (i.e., ioniconionic, hydrophilic/hydrophobic, functional groups) did not hamper the coating mechanism. Multiple coatings could also be applied with variation in the type of metal oxide precursor; this 'sequential coating' approach yielded complex structured materials of layered metal oxides, such as TiO2 and ZrO2. Coatings followed by casting (filling of the void space) gave a unique TiO2 coated bimodal pored (macroporous/mesoporous) silica.