Antifouling on Gecko's Feet Inspired Fibrillar Surfaces: Evolving from Land to Marine and from Liquid Repellency to Algae Resistance

In nature, biological creatures (including plants and animals) have self-cleaning capability despite the vagaries of the environment, i.e., from sky to land, and then to marine and vagaries of foulants (non-living and living). Gecko's feet have the general self-cleaning property both in air and underwater so as to keep their feet all clean for traveling through changing their adhesion. The present work reports Gecko's fibrillar structures to demonstrate general antifouling property in air through hydrophobicity and underwater after modification with hydrophilic polymer brushes. Fibrillar polypropylene (PP) nanoarrays are fabricated by hot embossing, exhibiting superhydrophobic antifouling in air. By grafting hydrophilic polyelectrolyte brushes (PSPMA) via surface-initiated atom transfer radical polymerization, they show superoleophobic antifouling of oil droplet and algae adhesion underwater. The effect of the structure of PP nanofiber arrays on the wettability and adhesion behavior is evaluated in detail. The results provide an important scientific principle for fabricating self-cleaning low-fouling materials with micro/nanostructure, with the hydrophobic ones being more applicable in air and the hydrophilic ones well suited underwater.