Ultrahydrophobic substrates
Disclosed is a process for modification of a substrate so as to form an ultrahydrophobic surface on the substrate. Also disclosed are surface-modified substrates that can be formed according to the disclosed processes. The process includes attachment of a multitude of nano- and/or submicron-sized structures to a surface to provide increased surface roughness. In addition, the process includes grafting a hydrophobic material to the surface in order to decrease the surface energy and decrease wettability of the surface. The combination of increase surface roughness and decreased surface energy can provide an ultrahydrophobic surface on the treated substrate.
1. A surface-modified substrate comprising:
a cross-linked anchoring layer that is an intermediate layer bound directly to the surface of a substrate;
a plurality of structures having a cross-section of from about 5 nanometers to about 1 micrometer indirectly grafted to the surface of the substrate via the intermediate layer;
wherein the average distance between individual structures is less than about three times the cross-section of the individual structures; and
a hydrophobic material grafted to the surface of the substrate; wherein the surface-modified substrate has a receding water contact angle greater than about 150° and has an advancing water contact angle greater than about 150°.
2. The surface-modified substrate of claim 1 , wherein the cross-linked anchoring layer comprises cross-linked poly(glycidyl methacrylate).
3. The surface-modified substrate of claim 1 , further comprising a cross-linked polymer layer overlaying the plurality of structures.
4. The surface-modified substrate of claim 3 , wherein the hydrophobic material is grafted to the cross-linked polymer layer.
5. The surface-modified substrate of claim 1 , wherein the hydrophobic material is a cross-linked hydrophobic polymer.
6. The surface-modified substrate of claim 1 , wherein the structures have a cross-section of from about 5 nanometer to about 500 nanometers.
7. The surface-modified substrate of claim 1 , wherein the structures are metallic.
8. The surface-modified substrate of claim 1 , wherein the structures are carbon-based.
9. The surface-modified substrate of claim 1 , wherein the structures have an aspect ratio greater than one.
10. The surface-modified substrate of claim 1 , wherein the average distance between individual structures is less than the cross-section of the individual structures.
11. The surface-modified substrate of claim 1 , wherein the substrate is a fibrous substrate.
12. The surface-modified substrate of claim 1 , wherein the substrate is a woven or nonwoven textile.
13. The surface-modified substrate of claim 1 , wherein the substrate comprises a polymer.
14. The surface-modified substrate of claim 13 , wherein the substrate comprises a synthetic polymer.