CORE-SHELL NANOPARTICLES
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.