Hydrophobic/Oleophobic Material

Abstract

A method of manufacturing a hydrophobic/oleophobic material comprises providing an open cell structure having a plurality of interconnected cells and providing a resin solution containing nanoparticles. The resin solution containing nanoparticles is introduced into, and is cured within, the interconnected cells of the open cell structure. By curing the resin solution containing nanoparticles within the interconnected cells of the open cell structure, a highly hydrophobic/oleophobic material can be produced which exhibits isotropic properties.

Claims

1. A method of manufacturing a hydrophobic/oleophobic material comprising: providing an open cell structure having a plurality of interconnected cells; providing a resin solution containing nanoparticles; introducing the resin solution containing nanoparticles into the interconnected cells of the open cell structure; and curing the resin solution containing nanoparticles within the interconnected cells of the open cell structure.

2. A method as claimed in claim 1, wherein the open cell structure is formed of a polymer.

3. A method as claimed in claim 1, wherein the open cell structure has a cell density in the range 5-40 cells per cm.

4. A method as claimed in claim 1, wherein, prior to the resin solution being cured therewithin, the open cell structure is resiliently compressible and expandable.

5. A method as claimed in claim 1, wherein the resin solution comprises 5-25% wt resin.

6. A method as claimed in claim 1, wherein the resin comprises a fluoro resin, a siloxane resin, or a fluoro-siloxane resin.

7. A method as claimed in claim 1, wherein the resin solution comprises an organic solvent.

8. A method as claimed in claim 1, wherein the resin solution comprises 60-90% wt solvent.

9. A method as claimed in claim 1, wherein the nanoparticles are metallic or non-metallic.

10. A method as claimed in claim 1, wherein the nanoparticles have at least one dimension in the range 1-100 nm.

11. A method as claimed in claim 1, wherein the resin solution comprises 5-15% wt nanoparticles.

12. A method as claimed in claim 1, wherein introducing the resin solution containing nanoparticles into the interconnected cells comprises immersing the open cell structure in the resin solution, and wherein introducing the resin solution containing nanoparticles into the interconnected cells further comprises compressing the open cell structure and then allowing the open cell structure to expand resiliently whilst immersed in the resin solution.

13. A method as claimed in claim 1, wherein the open cell structure is at least partially or substantially fully saturated with the resin solution following introduction of the resin solution containing nanoparticles into the interconnected cells of the open cell structure.

14. A method as claimed in claim 1, wherein the method further comprises removing an excess of resin solution from the open cell structure prior to curing the remaining resin solution within the interconnected cells, and wherein removing the excess of resin solution comprises at least one of i) allowing the excess resin solution to leave the open cell structure under gravity and ii) compressing the open cell structure to force the excess resin solution to leave the open cell structure.

15. A method as claimed in claim 1, wherein curing the resin solution containing nanoparticles within the interconnected cells takes place at least one of i) over a period of time in the range 12-36 hours and ii) at a temperature in the range 5-45° C.

16. A method as claimed in claim 1, wherein the method further comprises compressing the open cell structure at least one of i) during the curing of the resin solution within the interconnected cells and ii) after the curing of the resin solution within the interconnected cells.

17. A method as claimed in claim 16, wherein the compression ratio used when compressing the open cell structure is in the range 5:1-20:1.

18. A method as claimed in claim 16, wherein compressing the open cell structure takes place at least one of i) over a time period in the range 1-7 minutes and ii) at a temperature in the range 125-200° C.

19. A method as claimed in claim 1, wherein the method further comprises abrading one or more surfaces of the material.

20. A hydrophobic/oleophobic material comprising: an open cell structure having a plurality of interconnected cells, the interconnected cells of the open cell structure having a cured resin solution containing nanoparticles therewithin.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0021] By way of example only, embodiments of the invention will now be described in detail with reference being made to the accompanying drawings in which:

[0022] FIG. 1 illustrates a method of manufacturing a hydrophobic/oleophobic material according to an embodiment of the present invention;

[0023] FIG. 2 is a close-up view of a hydrophobic/oleophobic material according to an embodiment of the present invention taken with a scanning electron microscope; and

[0024] FIG. 3 shows a hydrophobic/oleophobic material according to an embodiment of the present invention with test liquid droplets thereon.

DETAILED DESCRIPTION OF THE FIGURES

[0025] FIG. 1 illustrates a method of manufacturing a hydrophobic/oleophobic material. In step 10 of the method, an open cell structure having a plurality of interconnected cells is provided. In this embodiment, the open cell structure comprises a sheet of polyurethane foam having a thickness in the range 10 mm-75 mm and a cell density in the range 5-40 cells per cm.

[0026] In step 12, a resin solution containing nanoparticles is provided. The resin solution is prepared by dissolving a “low surface energy” fluoro, siloxane or fluoro-siloxane resin in an organic solvent such as acetone, butanone, xylene, isopropanol, ethyl acetate or propylene glycol methyl ether acetate. Nanoparticles having at least one dimension which is in the range 1-100 nm are added to the resin solution and thoroughly dispersed using a high-shear mixer. In this embodiment, the nanoparticles are formed of silica, nickel or iron, but other suitable substances could be used. In this embodiment, the resin solution comprises 5-25% wt resin, 60-90% wt solvent and 5-15% wt nanoparticles, for example 15 g resin, 85 g solvent and 10 g nanoparticles.

[0027] In step 14, the resin solution is introduced into the interconnected cells of the open cell structure by immersing the open cell structure in a container which holds the resin solution. The open cell structure is compressed and then allowed to expand resiliently whilst in the container in order to draw the resin solution into the open cell structure. The open cell structure is then removed from the container and an excess of resin solution is removed by a combination of dripping under gravity and gentle compression of the open cell structure using compression rollers or plates.

[0028] In step 16, the resin solution within the interconnected cells of the open cell structure is cured. In this embodiment, curing takes place over a period of time in the range 12-36 hours at a temperature in the range 5-45° C.

[0029] In step 18, the open cell structure is then compressed using compression rollers or plates. This can help to make the resultant material tougher whilst still remaining flexible. In this embodiment, the compression ratio is in the range 5:1-20:1. The desired compression ratio is achieved by spacing the rollers appropriately or by placing an appropriately sized shim between the compression plates. In this embodiment, the compression takes place over a period of time in the range 1-7 minutes at a temperature in the range 125-200° C. The surface of the material is then abraded to roughen the surface of the material and thereby further improve the hydrophobicity/oleophobicity of the material, and modify its optical appearance. Contact angles of ˜155° for water, ˜120° for engine oil and hydraulic fluid, and ˜95° for diesel, have been achieved by following the above method.

[0030] FIG. 2 is a close-up view of a hydrophobic/oleophobic material 20 formed using the above method. This view was obtained using a scanning electron microscope. As is shown, the material 20 has an open cell structure 22 having a plurality of interconnected cells 24. The interconnected cells 24 of the open cell structure 22 have a cured resin solution 26 containing nanoparticles 28 therewithin. The nanoparticles 28 in the region of the open cell structure 22 are most visible in this view, but the nanoparticles 28 are also dispersed throughout the cured resin 26.

[0031] FIG. 3 also shows a hydrophobic/oleophobic material 30 formed using the above method. The material 30 has pairs of test liquid droplets thereon. The first pair of droplets 32 are engine oil, the second pair of droplets 34 are hydraulic fluid, and the third pair of droplets 36 are 2-stroke oil. The oleophobic nature of the material 30 is clearly evident from this FIG. 3 from the manner in which the droplets 32, 34, 36 sit on the surface of the material 30.