Biofouling-Inspired Growth of Superhydrophilic Coating of Polyacrylic Acid on Hydrophobic Surfaces for Excellent Anti-Fouling.

In this work, we demonstrated effective adsorption of poly(acrylic acid) (PAA) in saline water on various hydrophobic substrates, ranging from polyethylene and polytetrafluoroethylene, to form densely packed monolayers with water contact angle as low as 6.5° in air. This was a result of the synergy of long-range hydrophobic interactions between individual PAA chains and hydrophobic surfaces and short-range hydrogen bonding between neighboring PAA chains, reminiscent of the interaction balance encountered in biofouling. The PAA monolayers adsorbed on hydrophobic surfaces showed the ultrahigh packing density of surface COOH groups of 4.8 nm, which contributed to the surface superhydrophilicity and its stability against surface reconstruction during aging even at temperature higher than PAA glass transition. Further, conjugation of the adsorbed PAA monolayers with polyethylene glycol results in excellent antifouling with nearly zero adsorption of proteins.