Effect of self-assembly aggregation on physical properties of non-aqueous ionogels based on LMWG

Abstract

In recent years the low-molecular-weight gelators (LMWG) started to be used as a hardener for liquid electrolytes to create ionogels (OIG). The characteristic properties of gels created by LMWG, like thermal reversibility, very low critical concentration of the gelator, and huge versatility of possible compounds that can be used, were thought to give them advantage over commercial polymer gel electrolytes (PGE). However, the PGE are still dominating, mainly thanks to its superior mechanical resistance and wide temperature range when compared to OIG. The narrow temperature range of the gel phase existence in case of OIGs is the biggest disadvantage. This paper reports the interdisciplinary study on physical properties of created ionogels with nonaqueous electrolyte solutions of quaternary ammonium salts (TAMBr, TEABr, TBABr) and low-molecular-weight gelators for different molar concentrations of the electrolyte. It will be shown how the self-assembly aggregation phenomenon can be used to extend the temperature range of the ionogel phase existence. The thermal scanning conductometry (TSC) method was used to investigate the electric properties of the ionogels. To investigate the transport properties of the cations and solvent molecules in the gel and sol phase, the NMR diffusometry method was used. For identification of intermolecular interaction in studied systems, the NMR spectroscopy method was used and to study how the different salts influence on the properties of used solvent, the tuning-fork vibration viscosimetry method was used.

Supramolecular ionogels prepared with bis(amino alcohol)oxamides as gelators: ionic transport and mechanical properties

“…12 On the other hand, supramolecular ionogels possess certain disadvantages which are mainly related to their inferior mechanical strength and low(er) temperature range of their quasi-solid state with the sol-gel transition temperature being oen below 100 C. However, recent investigations reported on supramolecular ionogels with an enhanced mechanical strength and thermal stability. [13][14][15][16] Such results are promising and encourage further research in the direction for nding new LMWGs, which would efficiently gel ILs producing highly conductive, however mechanically and thermally stable supramolecular ionogels.…”

“…Indeed, storage modulus for the ionogel from the combination 6 containing 1 wt% of gelator 2 (optimal gelator concentration) reaches 278 kPa, which is higher than that of the strongest ionogel prepared by gelators based on urea (z160 kPa), 13 and that of highly temperature-stable ionogels prepared via metal-coordination interaction (z46 kPa). 15 Interestingly, such high mechanical strength is achieved in spite of the high gelator mobility (D Gelator on the order of 10 À12 m 2 s À1 ). Clearly, aggregation of gelator molecules with anions plays a major role, as discussed above, and this aggregation is responsible for the mechanical stability.…”

“…Literature reports various LMWGs which produce gels with ILs, including those based on glycolipids, 17 amino acids, 7,18,19 sorbitol derivatives, 8 urea and amides, 9,14 cholesterol derivatives, 13,20 carbene complexes, 21 amide derivatives [22][23][24] and D-gluconic acetal derivatives. 10,15 Also, recent study reports preparation of the supramolecular polymeric ionogel based on the host-guest nonchemically cross-linked interactions of cyclodextrin with adamantyl derivatives. 25 Recently, we have reported that (S,S)-bis(leucinol)oxamide efficiently gels imidazolium-based IL: 1-butyl-3-methylimidazolium tetra-uoroborate, [C 4 mim][BF 4 ], forming ionogels with high ionic conductivity and relatively large temperature range of the gelstate.…”

Self‐Assembled Rolled‐Up Microcoils for nL Microfluidics NMR Spectroscopy

“…The glycerol spectra are not fully resolved, but the peaks have the correct spacing. [ 19 ] In the unencapsulated case, a drop of glycerol was placed at the end of the polymeric tube and got sucked into the tube by capillary forces. The same forces caused some of the glycerol to crawl in the corners between tube and glass substrate, therefore placing some sample material outside of the microcoil.…”

Nuclear Magnetic Relaxation Mapping of Spin Relaxation in Electrically Stressed Glycerol

“…Discussion of T 1 and T 2 Variations in Electrically Stressed Glycerol. A recalculation of measured T 1 and T 2 times to the present temperatures using the calibration curves from Figure 8 should lead to a linear progression as any temperature-dependent changes, e.g., of chemical shifts, 50 are considered by experimental calibration curves. Hence, it is expected that the two derived temperatures will agree and should line up with the diagonal line in Figure 10.…”