Other antifouling coatings have been applied to various surfaces by processes that involve the use of harsh solvents. These solvents may cause damage to delicate substrate (such as RO membranes). The invented copolymer chemistry is the first-ever ultrathin (30 nm) and ultralow-fouling coating developed by initiated chemical vapor deposition (iCVD), a solvent-less technique. The ultrathin nature of the coating ensures unchanged productivity of purified water, because water flux decreases exponentially as coating thickness increases. Additionally, while fouling from membrane use can be reduced by remediation with chlorine, exposure to water with even a few parts per billion chlorine significantly degrades normal membrane performance. This polymer coating is chlorine-resistant, lowering the number of additional processing steps and, in turn, operational costs.