Antifouling and chlorine-resistant ultrathin coatings on reverse osmosis membranes

A composition, comprising a substrate and a coating material;

• wherein the coating material is on a surface of the substrate;
• wherein the substrate is a reverse osmosis membrane;
• and the coating material comprises a polymer comprising a plurality of first repeat units and a plurality of second repeat units;
• wherein
• the first repeat unit is
• wherein, independently for each occurrence,
• R is H, an alkyl, a halo, a hydroxy, an amino, a nitro, or a cyano;
• Y is a linker that does not comprise an amide bond, an ester bond, or an ether bond;
• and
• X⊖ is —SO3⊖, —HPO3⊖, or —CO2⊖;
• the second repeat unit is
• wherein, independently for each occurrence,
• R is H, an alkyl, a halo, a hydroxy, an amino, a nitro, or a cyano;
• and
• Z is a linker that does not comprise an amide bond, an ester bond, or an ether bond.