Hydrophobic article
A hydrophobic article includes a substrate and a nanoparticle layer disposed on the substrate and including nanoparticle agglomerates wherein the nanoparticle agglomerates have an average volume based size of at least 100 nanometers as determined using light scattering via ISO 13320. The hydrophobic article also includes a binder layer disposed on and in direct contact with the nanoparticle layer and including an oxidatively cured product of a silicon-based resin and an outermost layer that is disposed opposite the substrate and on and in direct contact with the binder layer. The hydrophobic article has a water contact angle of greater than or equal to 90 degrees as measured on the outermost layer of the hydrophobic article and determined using modified ASTM D5946-04.
1. A hydrophobic article comprising:
A. a substrate;
B. a nanoparticle layer disposed on said substrate and consisting of nanoparticle agglomerates wherein the nanoparticle agglomerates have an average volume based size of at least 100 nanometers as determined using light scattering via ISO 13320;
a binder layer disposed on and in direct contact with said nanoparticle layer and comprising an oxidatively cured product of a silicon-based resin selected from a polysilsesquioxane or a silsesquioxane having the formula:
(R 3 SiO 1/2 ) a (R 2 SiO 2/2 ) b (RSiO 3/2 ) c (SiO 4 ) d
wherein each R is independently selected from the group consisting of hydrogen, alkyl, alkenyl, and aryl groups or alkyl, alkenyl, and aryl groups substituted with halogen, nitrogen, oxygen, sulfur or silicon atoms, with the proviso that at least two R groups are hydrogen and wherein a, b, c and d are mole fractions, wherein a+b+c+d is 1, and wherein the sum of c and d is greater than zero; with a further proviso that such silicon-based resin comprises units of the formula: HSi(OH) x (OR) y O z/2 wherein each R is as defined above and x is 0 to 2; y is 0 to 2; z is 1 to 3; and the sum of x+y+z is 3; and
C. an outermost layer that is disposed opposite said substrate and on and in direct contact with said binder layer;
wherein said hydrophobic article has a water contact angle of greater than or equal to 90 degrees as measured on said outermost layer of said hydrophobic article and determined using modified ASTM D5946-04.
2. The hydrophobic article of claim 1 wherein said outermost layer is covalently bonded to said binder layer.
3. The hydrophobic article of claim 1 wherein said outermost layer is free of covalent bonds to said binder layer.
4. The hydrophobic article of claim 1 wherein said silicon-based resin has a molecular weight from 600 to 150,000 g/mol and has at least two silicon-bonded hydrogen groups per molecule.
5. The hydrophobic article of claim 1 wherein said outermost layer has a surface energy of less than 40 mN/m measured at 20° C.
6. The hydrophobic article of claim 1 further comprising an adhesive layer that comprises an adhesive and that is disposed on and in direct contact with said substrate and said nanoparticle layer.
7. The hydrophobic article of claim 6 wherein said adhesive is at least partially cured and is a silicon oxide.
8. The hydrophobic article of claim 6 having a water contact angle of greater than or equal to 80 degrees as determined using modified ASTM D5946-04 after 100 abrasion cycles.
9. The hydrophobic article of claim 1 wherein said nanoparticle agglomerates are formed from silica nanoparticles that are functionalized with an agglomerating agent chosen from amines, alcohols, diols, silanes, surfactants, hydroxy-terminated polymers, dithiols, mercaptans, and combinations thereof.
10. The hydrophobic article of claim 9 wherein said agglomerating agent is an organosilane.
11. The hydrophobic article of claim 1 wherein said outermost layer comprises a fluorine containing compound or wherein said outermost layer comprises a polyorganosiloxane.