Euryhaline Hydrogel with Constant Swelling and Salinity‐Enhanced Mechanical Strength in a Wide Salinity Range

Abstract

In nature, many biological organisms possess a unique osmoregulation feature that enables them to survive in environments of different salinity, which is called euryhaline characteristics (e.g., salmon that can survive in freshwater and seawater). Drawing inspiration from these salinity‐tolerant organisms, here a strategy that integrates two polymer chain segments with different salinity tolerances is reported to produce a euryhaline hydrogel with stable water retention, constant swelling properties, superoleophobicity, and low‐adhesion to oil in aqueous environments over a wide range of salinity. The formation of internal dynamic complementary crosslinks is a key structural factor of the euryhaline attributes. The euryhaline hydrogel‐coated meshes can be successfully utilized in various oil/aqueous phase separation in a wide range of salinity. Furthermore, by creating a double network with dynamic bonds, superior euryhaline hydrogel with unique salinity‐enhanced mechanical strength can be obtained. It is anticipated that the euryhaline hydrogel will have broad application prospects in complex and variable ionic environments.

A Solvent Regulated Hydrogen Bond Crosslinking Strategy to Prepare Robust Hydrogel Paint for Oil/Water Separation

“…Although many previous works have reported high strength hydrogels, maintaining mechanical strength for a long time in oil/water separation environments is still challenging because the heterogeneous swelling of hydrogels likely results in low polymer chain density and small friction between polymer chains. [10,26] Given that hydrogen bond crosslinking is an effective method to restrain swelling, [27] we have characterized the swelling properties and corresponding mechanical properties of PVA-TA and PVA-TA@SiO 2 under different conditions. As shown in Figure 3a, the equilibrium swelling ratio (ESR) of PVA-TA and PVA-TA@SiO 2 in highly acidic and saline environments was much lower than that of common hydrogels, only 6-18%, and the ESR of PVA-TA@SiO 2 was greater than that of PVA-TA.…”

“…In addition, the hydrogel coating applied to oil-water separation should exhibit good swelling stability, as water swelling usually results to deterioration of surface wetting and mechanical properties. [10] Dipping, spraying, brushing or shear coating is regarded as efficient technique to fabricate uniform coatings on large areas. [11] For hydrogel coatings on grid or porous substrates, the complete coating process normally involves the sol-gel transition.…”

Recovered Energy from Salinity Gradients Utilizing Various Poly(Acrylic Acid)-Based Hydrogels

“…Drawbacks of chemical hydrogels, in terms of mechanical properties, have been circumvented by adding nanoparticles to the polymer network or by utilizing double- or semi-interpenetrating networks [ 44 , 45 , 46 , 47 , 48 , 49 ]. The salinity responsiveness also makes hydrogels interesting for other applications such as desalination of fresh water from seawater [ 50 , 51 ], and separating various types of oil and aqueous solutions over a wide range of salinities [ 52 ].…”

Thermoresponsive Poly(N,N-diethylacrylamide-co-glycidyl methacrylate) Copolymers and Its Catalytically Active α-Chymotrypsin Bioconjugate with Enhanced Enzyme Stability

“…It is interesting to note that due to the better biocompatibility of the LCST-type thermoresponsive poly( N , N -diethylacrylamide) (PDEAAm) than that of PNIPAAm [ 65 ], investigations in relation to the responsive and biocompatible behavior of PDEAAm, its derivatives, and gels have gained increased attention only in recent years (see, e.g., Refs. [ 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ] and references therein). It should also be mentioned that aqueous PDEAAm solutions possess similar critical solution temperatures (CST) [ 72 , 93 , 94 , 95 , 96 ] in the range of ~25–40 °C than that of PNIPAAm [ 46 , 55 ].…”