Films and method of production thereof
A method of producing a film coated onto a substrate by dissolving a metal or metalloid containing compound having hydrolysable groups in a solvent to form a precursor solution. The precursor solution is coated onto the substrate as a continuous liquid phase. The precursor solution is then cured to produce a continuous, interconnected, nano-porous network.
1. A method of forming a film coated on a substrate including the steps of:
producing a precursor solution by dissolving a film precursor compound in an organic solvent, the film precursor compound comprising at least two hydrolysable groups bonded to a metal or metalloid;
coating a substrate with the precursor solution, the film precursor compound therein remaining substantially unhydrolysed; and
curing the precursor solution onto the substrate in a gaseous non-neutral pH environment comprising vaporous base, water and an organic solvent to thereby initiate hydrolysis and condensation reactions of the film precursor compound and cause adhesion of the forming film to the substrate,
wherein at least one of organic solvent content of the precursor solution and the organic solvent content in the gaseous environment are controlled to control characteristics of the film.
2. The method of claim 1 wherein the film precursor compound is a metal alkoxide or a metalloid alkoxide.
3. The method of claim 2 wherein the metal or metalloid alkoxide is an oligomer.
4. The method of claim 1 wherein the metal or metalloid is selected from the group consisting of silicon, germanium, tin, lead, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, yttrium, magnesium, calcium, strontium, barium, lead, zinc, cadmium, mercury, boron, aluminum, gallium, indium, and combinations thereof.
5. The method of claim 1 wherein the film precursor compound is an oligomeric organosilicate.
6. The method of claim 5 wherein the oligomeric organosilicate has a number n of repeating units between 2 to 10.
7. The method of claim 1 wherein the organic solvent in the precursor solution and the gaseous non-neutral pH environment are independently selected from the group consisting of an alcohol, a ketone, an amide and an ester.
8. The method of claim 7 wherein the organic solvent in the precursor solution and the gaseous non-neutral pH environment is an alcohol.
9. The method of claim 1 wherein the coating step is carried out by spin coating, dip coating, spray coating, fog coating, meniscus coating, slot coating, screen printing, roll coating or curtain coating.
10. The method of claim 1 wherein the base is ammonia.
11. The method of claim 1 wherein the steps are carried out at room temperature and atmospheric pressure.
12. The method of claim 1 wherein a pore size of the film is related to the size of the organic solvent molecule in the precursor solution or the gaseous environment.
13. The method of claim 1 wherein the organic solvent content in the precursor solution and/or the gaseous non-neutral pH environment relates to a pore density of the film.