Preparation of asymmetric porous materials
A method for preparing an asymmetric porous material by depositing a porous material film on a flexible substrate, and applying an anisotropic stress to the porous media on the flexible substrate, where the anisotropic stress results from a stress such as an applied mechanical force, a thermal gradient, and an applied voltage, to form an asymmetric porous material.
1. A method for preparing an asymmetric microporous material, comprising:
depositing a microporous material film on a flexible substrate, and
applying an anisotropic stress to said flexible substrate, said anisotropic stress resulting from a stress selected from an applied mechanical force, a thermal gradient, and an applied voltage, to form an asymmetric porous material;
wherein said microporous material film is formed of a majority of a material selected from the group consisting of silica, alumina, aluminosilicate, and titania.
2. The method of claim 1 wherein said flexible substrate comprises a piezoelectric material.
3. The method of claim 2 wherein said piezoelectric material is aluminum nitride.
4. The method of claim 2 wherein said anisotropic stress results from an applied voltage to said flexible substrate.
5. The method of claim 1 wherein said microporous material film has a thickness between 10 nanometers and 100 nanometers.
6. The method of claim 1 wherein said microporous material film is prepared by infiltrating a pore-filling medium into a host porous structure situated on the flexible substrate, and forming the interconnected cast is formed by polymerizing said pore-filling medium to form an interconnected cast, removing said host porous structure, forming a material around said interconnected cast, and removing said interconnected cast.
7. The method of claim 6 wherein said pore-filling medium is a polymerizable organic species selected from the group consisting of furfuryl alcohol, sucrose, and pyrrole.
8. The method of claim 6 wherein removing said host porous structure is performed by a method selected from acid digestion and base digestion.
9. The method of claim 6 wherein said further comprising:
forming a material around said interconnected cast is performed by a method selected from electroless solution deposition, electrochemical deposition, chemical vapor deposition, physical vapor deposition and sol infiltration with in-situ gelation.
10. The method of claim 1 wherein said microporous material film is prepared by infiltrating a pore-filling medium into a host porous structure situated on a flexible substrate, polymerizing said pore-filling medium to form an interconnect cast, and removing said host porous structure.
11. The method of claim 10 wherein removing said host porous structure is performed by a method selected from acid digestion and base digestion.
12. A method for preparing an asymmetric microporous material, comprising:
applying an anisotropic stress to a flexible substrate, said anisotropic stress resulting from a stress selected from an applied mechanical force, a thermal gradient, and an applied voltage;
depositing a microporous material film onto said stressed flexible substrate, and
removing said anisotropic stress to said flexible substrate to form an asymmetric microporous material;
wherein said microporous material film is formed of a majority of a material selected from the group consisting of silica, alumina, aluminosilicate, and titania.