Supramolecular hydrogel based on a sodium deep eutectic solvent

Abstract

A supramolecular hydrogel based on a metal-containing deep eutectic solvent (DES) is presented here for the first time. The phase diagram of the DES-based hydrogel was drawn and its rheological properties were determined.

Quest for Green‐Solvent Design: From Hydrophilic to Hydrophobic (Deep) Eutectic Solvents

“…Again, this is probably due to the more easily available charge on the nitrogen atom of the ammonium cation owing to the presence of at least one short alkyl chain. This observation is in line with the recently reported hydrogel formation when NaC 12 /C 10 (1:4) comes into contact with water, which was explained by the presence of the sodium ions . Overall, the water solubility can be ranked by family of hydrophobic (D)ESs according to following order: fatty acids<menthol<thymol<quaternary ammonium salts, where fatty acid‐based ESs solubilize ≤5 wt % of water, menthol‐based ESs less than 2.5 wt %, thymol‐based DESs less than 3.7 wt %, and finally long‐alkyl‐chain‐ammonium salt‐based (D)ESs solubilize between 2 and 7 wt % of water.…”

“… Comparison of solid–liquid phase diagrams of a DES composed of sodium dodecanoate and decanoic acid (• NaC 12 /C 10 ) and an ES composed of a natural compound, l ‐menthol and decanoic acid (▪ l (−)‐menthol/C 10 ) . The data refers to the liquid‐to‐solid–liquid phase transition.…”

“…The use of these acids was inspired by phase‐change materials, but the components were carefully chosen to obtain eutectic melting points below room temperature. In a subsequent work, Florindo et al . presented a family of hydrophobic (D)ESs containing a sodium salt of a fatty acid acting as HBA and another fatty acid acting as HBD.…”

“…Neutral hydrophobic (D)ESs are essentially eutectic mixtures, showings mall depressions in the meltingp oints, leading to highly fluid solvents, av ery appealing property fors ome applications. Figure 6s hows ad irect comparison of phase diagramso ft wo hydrophobic (D)ESs, one composed of sodium dodecanoate and decanoic acid [7] and the other containing l(À)-menthol and decanoic acid.…”

Self‐Assembled Gels Formed in Deep Eutectic Solvents: Supramolecular Eutectogels with High Ionic Conductivity

“…[18] Arecent study used silica-based materials to immobilise DESs;the resulting gels were referred to as "eutectogels" for the first time,and their application in Li/Liion batteries was demonstrated. [19] However,tothe best of our knowledge,t here are no reports of supramolecular gels formed in DESs by self-assembly.I ns ome cases,t wocomponent "deep eutectic" systems have themselves been applied as supramolecular gelators by addition to traditional solvents [20] -but this is significantly different to developing supramolecular gelators that can be added to DESs,t hus immobilising them, as targeted in this study.Asnoted above, DESs have inherent noncovalent interactions within their structures,w hich may interfere with self-assembly of the LMWG into an anoscale network (or the LMWG may limit DES performance). Such processes urgently need investigation.We therefore targeted supramolecular gels based on DESs,r easoning that such materials could have very high value in, for example,e nergy applications.…”