Versatile Supramolecular Gelators That Can Harden Water, Organic Solvents and Ionic Liquids

Abstract

We developed novel supramolecular gelators with simple molecular structures that could harden a broad range of solvents: aqueous solutions of a wide pH range, organic solvents, edible oil, biodiesel, and ionic liquids at gelation concentrations of 0.1-2 wt %. The supramolecular gelators were composed of a long hydrophobic tail, amino acids and gluconic acid, which were prepared by liquid-phase synthesis. Among seven types of the gelators synthesized, the gelators containing L-Val, L-Leu, and L-Ile exhibited high gelation ability to various solvents. These gelators were soluble in aqueous and organic solvents, and also in ionic liquids at high temperature. The gelation of these solvents was thermally reversible. The microscopic observations (TEM, SEM, and CLSM) and small-angle X-ray scattering (SAXS) measurements suggested that the gelator molecules self-assembled to form entangled nanofibers in a large variety of solvents, resulting in the gelation of these solvents. Molecular mechanics and density functional theory (DFT) calculations indicated the possible molecular packing of the gelator in the nanofibers. Interestingly, the gelation of an ionic liquid by our gelator did not affect the ionic conductivity of the ionic liquid, which would provide an advantage to electrochemical applications.

Thermal Properties, Conductivity, and Spin-lattice Relaxation of Gel Electrolyte Based on Low Molecular Weight Gelator and Solution of High Temperature Ionic Liquid

“…Depending on the nature of gelator, gel electrolytes can be classified into polymer gel electrolytes [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and low molecular weight gel electrolytes [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The former are in most of the cases the chemical gels formed as a result of polymerization reactions and chemical bonding.…”

“…The latter ones are always physical gels formed by the self-assembly of low molecular weight gelators (LMWGs) in liquid media (solution of electrolytes or ionic liquids) through the intermolecular interactions such as hydrogen bonding, p-p stacking, van der Waals and electrostatic interactions, coordination, or charge transfer. As a result of such interactions a three dimensional network of LMWGs aggregates is formed which adsorbs (incorporates) solvent into its structure [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The low molecular weight gel electrolytes are thermoreversible.…”

“…Moreover, it allows also to create gel electrolyte inside the device, thus improving contacts between the cell elements. Unlike the polymer gel electrolytes, low molecular weight gel electrolytes can be formed with a small weight percent of gelator and it has been found that ionic conductivities of gels are similar to those of the pure electrolyte [15][16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Supramolecular Ionic‐Liquid Gels with High Ionic Conductivity

“…Basically,i onogels can be prepared by additiono f1 )low molecular weights upramolecular gelators, 2) polymers, or 3) inorganic particles( SiO 2 nanoparticles, metal/metal oxide nanoparticles, carbon nanotubes, etc.). [4] Amongt hese,s upramolecular gelators appeart ob ee specially efficient, since they have the smallest influence on ion dynamics upon confinement.I tw as shown that the gelation of ILs by gelators basedo na mino acids, [5][6][7] urea and amides, [8] carbene complexes, [9] and other amide derivates [10,11] results in ionogelsw ith ionic conductivities slightly lower than those of pure ILs. Moreover,t he gelation of ILs by supramolecular gelators is at hermoreversible process that enables the preparation of ionogels with temperature-controlled sol-gel transitions.…”

Novel approach in determination of ionic conductivity and phase transition temperatures in gel electrolytes based on Low Molecular Weight Gelators

“…The most important part of the gel electrolyte system is the gelator, depending on its nature, the polymer gel electrolytes [12][13][14][15][16][17][18][19][20][21][22][23][24][25] and low molecular weight gel electrolytes [26][27][28][29][30][31][32][33][34][35][36][37][38][39] can be distinguished. Polymer gels are formed as a result of polymerization reactions and chemical bonding resulting in high thermal stability but no thermal reversibility.…”