Nanotube Assisted Self-Cleaning Material

Abstract

A self-cleaning material is generally described that may include a substrate having a first surface. A self-cleaning layer of aligned nanotube structures may be formed on the first surface of the substrate, where absorption of light by the nanotube structures may cause a change in state of the self-cleaning material based on an angle of incidence of the light and an orientation vector corresponding to the layer of aligned nanotube structures.

1 . A method of making a self-cleaning material, the method comprising:
 providing a substrate having a first surface; and   forming a first self-cleaning layer of longitudinally aligned nanotube structures on the first surface of the substrate, wherein longitudinal axes of the nanotube structures are parallel to each other and form a first non-zero acute orientation angle with respect to an axis normal to the first surface.   
     
     
         2 . The method of  claim 1 , wherein the forming the first self-cleaning layer includes growing the nanotube structures on the substrate. 
     
     
         3 . The method of  claim 1 , wherein the forming the first self-cleaning layer includes depositing the nanotube structures on the substrate. 
     
     
         4 . The method of  claim 1 , wherein the first self-cleaning layer changes state responsive to an exposure to light based at least in part on an angle of incidence of the light and the first orientation angle. 
     
     
         5 . The method of  claim 4 , wherein the first self-cleaning layer is further arranged such that absorption of light by the self-cleaning layer of aligned nanotube structures increases as the angle of incidence of the light approaches the first orientation angle. 
     
     
         6 . The method of  claim 1 , wherein the self-cleaning layer of aligned nanotube structures is photocatalytic, hydrophobic, and/or hydrophilic in response to exposure to the light. 
     
     
         7 . The method of  claim 1 , wherein the nanotube structures are a different material than the substrate. 
     
     
         8 . The method of  claim 7 , wherein the nanotube structures at least partially comprise titanium dioxide and the substrate is a glass. 
     
     
         9 . The method of  claim 1 , further comprising:
 forming a second self-cleaning layer of longitudinally aligned nanotube structures on a second surface of the substrate, wherein second longitudinal axes of the nanotube structures of the second self-cleaning layer are parallel to each other and form a second non-zero acute orientation angle with respect to an axis normal to the second surface.   
     
     
         10 . The method of  claim 9 , wherein the nanotube structures of the first self-cleaning layer and the nanotube structures of the second self-cleaning layer are different materials. 
     
     
         11 . The method of  claim 10 , wherein the second self-cleaning layer exhibits a different self-cleaning property than the first self-cleaning layer. 
     
     
         12 . The method of  claim 10 , wherein the first orientation angle is selected based on the first self-cleaning layer being utilized in an uncontrolled environment and the second orientation angle is selected based on the second self-cleaning layer being utilized in a controlled environment. 
     
     
         13 . A method of making a self-cleaning material, the method comprising:
 providing a substrate having a first surface;   depositing a seed layer on the first surface of the substrate; and   forming a self-cleaning layer of longitudinally aligned nanotube structures on the seed layer, wherein longitudinal axes of the nanotube structures are parallel to each other and form a non-zero acute orientation angle with respect to an axis normal to the first surface.   
     
     
         14 . The method of  claim 13 , wherein the forming the first self-cleaning layer includes growing the nanotube structures on the substrate. 
     
     
         15 . The method of  claim 13 , wherein the seed layer is a different material than the substrate. 
     
     
         16 . The method of  claim 13 , wherein the self-cleaning layer changes state responsive to an exposure to light based at least in part on an angle of incidence of the light and the orientation angle. 
     
     
         17 . The method of  claim 16 , wherein the self-cleaning layer is further arranged such that absorption of light by the self-cleaning layer of the aligned nanotube structures increases as the angle of incidence of the light approaches the orientation angle. 
     
     
         18 . A method of using a self-cleaning material, the method comprising:
 attaching the self cleaning material to a support structure, the self cleaning material comprising:
 a substrate having a first surface, and 
 a self-cleaning layer of longitudinally aligned nanotube structures on the first surface of the substrate, wherein longitudinal axes of the nanotube structures are parallel to each other and form a non-zero acute orientation angle with respect to an axis normal to the first surface; and 
   illuminating the self-cleaning material with light, the illuminating causing the self-cleaning layer to change state responsive to exposure to the light based at least in part on an angle of incidence of the light and the orientation angle.   
     
     
         19 . The method of  claim 18 , wherein the support structure is included in an uncontrolled environment, and the orientation angle of the nanotube structures is selected based upon environmental parameters. 
     
     
         20 . The method of  claim 18 , wherein the support structure is included in a controlled environment, and the orientation angle is selected to match the angle of incidence of the light from of a fixture illuminating the self-cleaning material.