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Biofouling of man-made surfaces by marine organisms is a global problem with both financial and environmental consequences. However, the development of non-toxic anti-biofouling coatings is challenged by the diversity of fouling organisms. One possible solution leverages coatings composed of diverse chemical constituents. Reversible addition-fragmentation chain-transfer (RAFT) photopolymerization was used to modify poly(dimethylsiloxane) (PDMSe) surfaces with polymeric grafts composed of three successive combinations of acrylamide, acrylic acid, and hydroxyethyl methacrylate. RAFT limited conflicting variables and allowed for the effect of graft chemistry to be isolated. While all compositions enhanced the anti-biofouling performance compared with the PDMSe control, the ternary, amphiphilic copolymer was the most effective with 98% inhibition of the attachment of zoospores of the green alga Ulva linza , 94% removal of cells of the diatom Navicula incerta , and 62% removal of cells of the bacterium Cellulophaga lytica . However, none of the graft compositions tested were able to mitigate reattachment of adult barnacles, Amphibalanus amphitrite .

Effectively negating the deleterious impact of marine biofouling on the world's maritime fleet in an environmentally conscientious manner presents a difficult challenge due to a variety of factors including the complexity and diversity of fouling species and the differing surface adhesion strategies. Understanding how surface properties relate to biofouling can inform and guide the development of new antibiofouling coatings to address this challenge. Herein, we report on the development of a living photopolymerization strategy used to tailor the surface properties of silicone rubber using controlled anisotropic poly(acrylamide) patterns and the resulting antibiofouling efficacy of these surfaces against zoospores of the model marine fouling organism, Ulva linza . Chemical patterns were fabricated using reversible addition-fragmentation chain-transfer (RAFT) living polymerization in conjunction with photolithography. Pattern geometries were inspired by the physical (i.e., nonchemical) Sharklet engineered microtopography system that has been shown to be effective against the same model organism. Sharklet chemical patterns and analogous parallel channels were fabricated in sizes ranging from 2 to 10 μm in the lateral dimension with tailorable feature heights ranging from tens to hundreds of nanometers. Nonpatterned, chemically grafted poly(acrylamide) silicone surfaces inhibited algal spore attachment density by 59% compared to the silicone control; however, attachment density on chemical nanotopographies was not statistically different from the control. While these results indicate that the chemical nanotopographies chosen do not represent an effective antibiofouling coating, it was found that the Sharklet pattern geometry, when sized below the 5 μm critical attachment size of the spores, significantly reduced the algal spore density compared to the equally sized channel geometry. These results indicate that specific chemical geometry of the proper sizing can impact the behavior of the algal spores and could be used to further study the mechanistic behavior of biofouling organisms.