Core-shell nanoparticles

Abstract

Compositions suitable for forming an optical coating are provided, wherein the compositions include core-shell nanoparticles having (a) a core material which includes a polymer; and (b) a shell material which includes a metal oxide.

1 . A process for forming an anti-reflective coating on a substrate, the process comprising:
 (i) providing a coating composition comprising core-shell nanoparticles, wherein the nanoparticles have an average size of 10-200 nm and comprise (a) a core material comprising a cationic polymer; and (b) shell material comprising metal oxide deposited onto the cationic polymer;   (ii) applying the coating composition to a substrate to thereby obtain an applied coating;   (iii) curing the applied coating; and   (iv) subjecting the applied coating to an elevated temperature sufficient to remove some or all of the core material from the core-shell nanoparticles in the applied coating.   
     
     
         2 . The process according to  claim 1 , wherein steps (iii) and (iv) are carried out simultaneously. 
     
     
         3 . The process according to  claim 2 , wherein steps (iii) and (iv) are practiced by heating the applied coating to cause the core material to be at least partially thermally degraded. 
     
     
         4 . The process according to  claim 1 , wherein the core material is thermo-labile at a temperature of 150° C. to 600° C., the substrate is inorganic, and curing is carried out at at least 150° C. 
     
     
         5 . The process according to  claim 1 , wherein the substrate is inorganic and curing is carried out at 200-700° C. 
     
     
         6 . The process according to  claim 1 , wherein the resulting coating has a thickness of 50-300 nm. 
     
     
         7 . The process according to  claim 1 , wherein the cationic polymer is a cationic vinyl copolymer. 
     
     
         8 . The process according to  claim 1 , wherein the cationic polymer is a cationic vinyl copolymer having cationic groups incorporated therein during polymerization and comprising a poly(meth)acrylate or a copolymer thereof 
     
     
         9 . The process according to  claim 1 , wherein the cationic polymer is a selected from the group consisting of latexes, diblock-copolymers, triblock copolymers, and combinations thereof. 
     
     
         10 . The process according to  claim 1 , wherein the metal oxide is silica. 
     
     
         11 . The process according to  claim 1 , wherein the composition comprises a binder comprising an inorganic material. 
     
     
         12 . The process according to  claim 1 , wherein the nanoparticles have a potential void fraction, resulting from partially or fully removing the core material from the nanoparticle, of 5% to 90%. 
     
     
         13 . The process according to  claim 1 , wherein steps (iii) and (iv) are practiced simultaneously by subjecting the applied coating to an elevated temperature of from 150° C. to 600° C. 
     
     
         14 . The process according to  claim 14 , wherein the metal oxide is silica. 
     
     
         15 . The process according to  claim 15 , wherein the substrate is inorganic. 
     
     
         16 . The process according to  claim 15 , wherein the composition comprises a binder comprising an inorganic material. 
     
     
         17 . The process according to  claim 15 , wherein the resulting coating has a thickness of 50-300 nm. 
     
     
         18 . A substrate comprising an anti-reflective coating formed by the process of  claim 1 . 
     
     
         19 . A substrate comprising an anti-reflective coating formed by the process of  claim 17 . 
     
     
         20 . A process for forming an anti-reflective coating on a substrate, the process comprising:
 forming core-shell nanoparticles having an average size of 10-200 nm by depositing a shell material comprising silica onto a core material which comprises a cationic polymer;   (ii) forming a coating composition comprising the core-shell nanoparticles;   (iii) applying the coating composition to a substrate to thereby obtain an applied coating;   (iv) curing the applied coating; and   (v) subjecting the applied coating to an elevated temperature sufficient to remove some or all of the core material from the core-shell nanoparticles in the applied coating.