Poly(vinyl alcohol)-containing and silica nanoparticle multilayer coatings and methods

A method of making an article, the method comprising:

• a. providing a substrate;
• b. attaching a multilayer coating to a surface of the substrate, the attaching comprising
• i. forming a first silica layer that is a primer layer of the multilayer coating directly attached to the substrate, the first silica layer comprising a plurality of acid-sintered interconnected silica nanoparticles arranged to form a continuous three-dimensional porous network;
• and
• ii. forming a first PVA-containing layer directly adjacent to the first silica layer, the first PVA-containing layer comprising between 10 weight percent and 100 weight percent PVA;
• wherein the forming of the first silica layer and the forming of the first PVA-containing layer comprises:
• A. flowing a first fluid down a first slide surface of a slide coater, the first fluid comprising a plurality of acidified silica nanoparticles and corresponding to the first silica layer;
• B. flowing a second fluid down a second slide surface of the slide coater to form a second fluid layer over the first slide surface, the second fluid comprising PVA and corresponding to the first PVA-containing layer;
• and
• C. coating the substrate with the first fluid and the second fluid, to form a multilayer fluid coating, the first fluid being the lowermost fluid of the multilayer fluid coating and coated directly onto the substrate by the slide coater.