Sol-gel based antireflective coatings using alkyltrialkoxysilane binders having low refractive index and high durability

摘要

Methods and compositions for forming porous low refractive index coatings on substrates are provided. The method comprises coating a substrate with a sol-formulation comprising silica based nanoparticles and an alkyltrialkoxysilane based binder. Use of the alkyltrialkoxysilane based binder results in a porous low refractive index coating having bimodal pore distribution including mesopores formed from particle packing and micropores formed from the burning off of organics including the alkyl chain covalently bonded to the silicon. The mass ratio of binder to particles may vary from 0.1 to 20. Porous coatings formed according to the embodiments described herein demonstrate good optical properties (e.g. a low refractive index) while maintaining good mechanical durability due to the presence of a high amount of binder and a close pore structure.

主权项

1. A method of forming a porous coating on a substrate, comprising:
coating a substrate with a sol-formulation comprising:
an alkyltrialkoxysilane-based binder having the formula: wherein at least one of R1, R2, and R3 represents an alkyl group containing 1 to 20 carbon atoms selected from the group consisting of n-pentyl, isopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, methoylcyclohexyl, octyl, and ethylcyclohexyl or an aryl group containing 6 to 20 carbon atoms selected from the group consisting of benzyl and xylyl;wherein R4 represents a fluoro-modified alkyl group containing 1 to 20 carbon atoms; andsilica based nanoparticles, wherein a mass ratio of the alkyltrialkoxysilane-based binder to the silica based nanoparticles is between 0.1:1 to 20:1;wherein the sol-formulation further comprises an alcohol containing solvent and an acid or base containing catalyst;wherein the sol-formulation further comprises rare-earth-based oxide nanoparticles, the rare-earth-based oxide nanoparticles comprising at least one of Y2TeO11, Y2Te5O13, YInGe2O2:Eu3+, yttrium aluminum garnet (YAG) doped with Eu3+ ions, La(1−x)EuxMn0-9Zn0-1O3+d (LEMZ), Y2O3:Eu3+, or a combination thereof; and annealing the coated substrate.