Method of manufacturing ultrahydrophobic substrates
A process for modification of a substrate so as to form an ultrahydrophobic surface on the substrate is provided. Surface-modified substrates that can be formed according to the disclosed processes are also provided. 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 increased surface roughness and decreased surface energy can provide an ultrahydrophobic surface on the treated substrate.
1. A method for modifying the surface of a substrate comprising:
grafting a plurality of structures to a substrate at a surface of the substrate, wherein the structures have a cross-section of between about 1 nanometer and about 1 micrometer, wherein the average distance between individual structures grafted to the substrate is between about the cross-section of the individual structure and about three times the cross-section of the individual structures;
forming an anchoring layer on the substrate surface such that the anchoring layer is directly bound to the substrate surface and the plurality of structures are indirectly bound to the substrate via the anchoring layer;
forming a polymer layer on the substrate, wherein the polymer layer overlays the anchoring layer and overlays the plurality of structures bound to the anchoring layer; and
grafting a hydrophobic material to the polymer layer;
wherein the substrate surface including the anchoring layer, the plurality of structures, the polymer layer, and the hydrophobic material has a receding water contact angle greater than about 150° and has an advancing water contact angle greater than about 150°.
2. The method according to claim 1 , wherein the hydrophobic material is graft polymerized to the polymer layer.
3. The method according to claim 1 , further comprising grafting an additional material to the substrate.
4. The method according to claim 1 , wherein the step of forming the anchoring layer comprises applying an anchoring layer polymer comprising multiple epoxy groups to the substrate surface.
5. The method according to claim 4 , the substrate being formed of a material including reactive functional groups, the method further comprising reacting only a portion of the epoxy groups of the anchoring layer polymer with the reactive functional groups of the substrate to bind the anchoring layer directly to the substrate surface.
6. The method according to claim 4 , further comprising cross-linking the anchoring layer polymer.
7. The method according to claim 1 , further comprising crosslinking the polymer layer.
8. The method according to claim 1 , wherein the polymer layer is formed of a polymer that includes multiple epoxy groups.
9. The method according to claim 1 , further comprising initiating a surface charge on the plurality of structures.
10. The method according to claim 1 , wherein the anchoring layer and the polymer layer include the same polymer.
11. The method according to claim 1 , wherein the anchoring layer is formed of expoxidized poly(glycidyl methacrylate).