Nanoporous materials, manufacture of nanoporous materials and applications of nanoporous materials
A nanoporous material is disclosed having a plurality of lamellae. Through each lamella is an array of penetrating pores. Adjacent lamellae are spaced apart by an intervening spacing layer. The spacing layer comprises an array of spacing elements integrally formed with and extending between the adjacent lamellae. The spacing layer has interconnected porosity extending within the spacing layer. Such a nanoporous material can be manufactured using block copolymer materials. First, a morphology is formed comprising a three dimensional array of isolated islands in a continuous matrix. The islands are formed of at least one island component of the block copolymer and the matrix is formed of at least one matrix component of the block copolymer. Next, channels are formed in the matrix between at least some of the islands. The island component is then selectively removed to leave the matrix with an array of interconnected pores.
1. A method of manufacturing a nanoporous material comprising:
forming a morphology comprising a three dimensional array of isolated islands in a continuous matrix, wherein the islands are formed of at least one island component of a block copolymer and the matrix is formed of at least one matrix component of the block copolymer;
causing a solvent to diffuse through the matrix, the island component having a preferential solubility in the solvent and thereby increasing osmotic pressure in the islands;
forming channels in the matrix between at least some of the islands due to the increasing osmotic pressure in the islands; and
selectively removing the island component to leave the matrix with an array of interconnected pores.
2. The method according to claim 1 wherein the islands are substantially equi-axed.
3. The method according to claim 1 wherein the islands have an average diameter of between 5 nm and 100 nm.
4. The method according to claim 1 wherein the three dimensional array of islands is a substantially ordered array.
5. The method according to claim 4 wherein there is a regular minimum spacing between adjacent islands, and where the average diameter of the islands is d, the regular minimum spacing between adjacent islands is at least 1.5 d.
6. The method according to claim 1 wherein the number fraction of monomer units in the island component of the block copolymer is between 1-20%.
7. The method according to claim 6 wherein the number fraction of monomer units in the island component of the block copolymer is at least 5-8%.
8. The method according to claim 1 wherein the composition used to form the three dimensional array of isolated islands in a continuous matrix comprises one or more homopolymers added to a diblock copolymer.
9. The method according to claim 8 wherein the homopolymer additive is formed from the same monomer units as is used for the matrix component of the morphology or is a material that is miscible in the matrix component.
10. The method according to claim 8 wherein the homopolymer additive is formed from the same monomer units as is used for the island component of the morphology or is a material that is miscible in the island component.
11. The method according to claim 8 wherein the sum of the number fraction of monomer units of homopolymer for integration with the matrix and the number fraction of monomer units of matrix component is 1-99%.
12. The method according to claim 8 wherein the sum of the number fraction of monomer units of homopolymer for integration with the islands and the number fraction of monomer units of island component is 1-20%.
13. The method according to claim 1 wherein the island morphology is developed by thermal treatment.
14. The method according to claim 1 wherein the matrix is treated by cross-linking.
15. The method according to claim 14 wherein the islands degrade in response to the cross-linking treatment applied to the matrix.
16. The method according to claim 15 wherein the degraded islands are removed using a washing fluid.
17. The method according to claim 16 wherein the matrix component comprises polystyrene, the island component comprises PMMA and the washing fluid comprises acetic acid.
18. The method according to claim 14 wherein the material is subjected to a gaseous oxidising agent during the cross-linking of the matrix.
19. The method according to claim 18 further comprising:
using UV radiation to cross link the matrix; and
wherein the gaseous oxidising agent is ozone formed due to interaction of oxygen gas with the UV radiation used to cross link the matrix.
20. The method according to claim 18 wherein the gaseous oxidising agent is selected from ozone, sulphur, chlorine and fluorine.
21. The method according to claim 1 wherein the nanoporous material has a plurality of lamellae, each lamella having an array of pores penetrating therethrough, adjacent lamellae being spaced apart by an intervening spacing layer wherein the spacing layer comprises an array of spacing elements integrally formed with and extending between the adjacent lamellae, the spacing layer having interconnected porosity extending within the spacing layer.