Described herein are protective coatings for reverse osmosis membranes comprising coating mixtures of graphene oxide crosslinked with copolymers. The crosslinked GO copolymer mixture coatings provide protection from chlorine-based defoulers of saline water and unprocessed fluids. The coated membranes described herein create a reverse osmosis structure that has excellent water flux and salt rejection. The crosslinking copolymers can comprise an optionally substituted vinyl imidazole constituent unit and an optionally substituted acrylic amide constituent unit.