‘Fish-scale’-mimicked stretchable and robust oil-wettability that performs in various practically relevant physically/chemically severe scenarios

Abstract

A covalently cross-linked ‘reactive’ multilayer was strategically associated with a stretchable fibrous substrate to design a ‘fish-scale’-mimicked stretchable and durable interface, which was capable of sustaining high tensile deformation (150%) for 1000 times, and it was also efficient in performing under various physically/chemically severe scenarios.

Recent Advances in Robust Superwettable Membranes for Oil–Water Separation

“…Therefore, in addition to the required antiabrasion ability, other mechanical properties of the coating and bulk membrane materials, such as tensile strength, flexibility, elongation, and toughness, are of very importance for stable oil–water separation. These can be examined by the previously mentioned stress–strain, stretching/deformation, bending, tape peeling, scratching, ultrasonication, and laundering tests …”

“…As an example, a superhydrophobic fibrous PU membrane modified with BPEI/5Acl nanocomplexes (NC) was gradually deformed for 1000 cycles with 150% strain and retained super‐water‐repellency and a contact angle hysteresis of less than 10° . From the same research group, fish‐scale‐inspired stretchable underwater superoleophobic membranes with covalently cross‐linked NC multilayers based on a layer‐by‐layer assembly process and postcovalent modification with glucamine molecules showed good wettability and oil–water separation performance after up to 1000 stretching/deformation cycles ( Figure a–c) . At a deformation degree of 200%, the superhydrophobic PU@Fe 3 O 4 @SiO 2 @fluoropolymer (FP) sponges still showed water jet bouncing behavior (Figure d), but the WSAs increased gradually (Figure e).…”

“…c) Oil–water separation by a membrane after 1000 stretching cycles. (a–c) Reproduced with permission . Copyright 2018, the Royal Society of Chemistry.…”

“…Finally, although the abovementioned testing strategies are based on measuring contact angles (Figure a,b) or measuring the change in oil–water (non‐corrosive) separation performance after corrosion (Figure c), which reflect chemical resistance, the practical separation of a variety of complex oil–water mixtures composed of corrosive solutions or organic solvents to imitate real harsh conditions also makes sense (Figure d). Several separation systems especially for corrosive water–oil mixtures, water–organic solvents mixtures, and corrosive water–organic solvents mixtures have been established.…”

“…Thus, the design of unique membranes with special wettable, self‐cleaning, or photocatalytic surfaces to prevent fouling has become an emerging developing research field . An important property characterizing the environmental durability is the thermal stability of superwettable membranes, as well as humidity resistance . In addition, the durability of porous superwettable membranes against outdoor UV irradiation is often investigated, thus providing an approximation to membrane durability in the real environment …”