Fluorine-free superwetting systems: construction of environmentally friendly superhydrophilic, superhydrophobic, and slippery surfaces on various substrates

Abstract

Surfaces that exhibit extreme wetting properties such as superhydrophobic and/or slippery liquid-infused porous surfaces (SLIPS) rely heavily on their surface energy and roughness. Although the bioaccumulation and dramatic ecological impact of perfluorinated building blocks are obvious, perfluorination of surfaces is still the most utilized method for lowering the surface energy. Herein we present a simple, substrate-independent, completely fluorine free and environmentally friendly concept for the construction of various super-wetting systems. Taking advantage of a mussel-inspired polyglycerol we successfully fabricated superhydrophilic, superhydrophobic and slippery surfaces by the precise design of a highly hierarchical structure. Additionally, the superhydrophobic coating was used to transfer commercially available cellulose and polystyrene 3D sponges into stable superhydrophobic but superoleophilic absorbent materials for oil/water separation. Moreover, the alkylated, hierarchical structure can serve as a matrix to efficiently capture hydrocarbon liquids as a lubricant that results in SLIPS. Surprisingly, common sunflower oil from the supermarket showed the same performance as pure chemicals such as hexadecane. Both the superhydrophobic and the slippery surfaces showed a similar performance regarding liquid and cell repellency in comparison to their fluorinated analog.