The effect of eight potassium salts (KF, K 3 PO 4 , KOCN, K 2 CO 3 , KCl, K 2 SO 4 , KBr and 2 KI) on glycerol carbonate (GC) is studied through NMR, DSC, solubility and ATR-3 FTIR experiments. From the solubility data, the main thermodynamic functions of 4 solution and solvation are estimated, and the mean molal activity coefficients are 5 calculated. The results suggest that the capability of an anion to establish hydrogen 6 bonds with the solvent molecules (or behave as a base, as in the case of fluoride, 7 phosphate, cyanate and carbonate) is the most important structural feature that 8 determines its effects on the solvent structure. On the other hand potassium iodide 9 behaves in an anomalous way, due to the large polarizability of the anion that can 10 form non-electrostatic, van der Waals dispersive intermolecular interactions.

Glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one, shortly GC) is a dense, viscous, water soluble solvent. The high dielectric constant and dipole moment make it a suitable non-aqueous green solvent for several salts in different applications. GC dissolves significant amounts of inorganic salts such as KF. The saturation of GC with KF leads to the formation of a viscous liquid at room temperature. In this paper, we report on conductivity, rheology, differential scanning calorimetry and infrared spectroscopy experiments that indicate the formation of a glassy liquid where GC molecules and KF ion pairs are intercalated in a firm and ordered bidimensional structure, stabilized by hydrogen bonding and strong ion-dipole interactions.

The specific effects induced by some strong electrolytes or neutral cosolutes on aqueous mixtures of guar gum (GG), sodium alginate (SA) and sodium hyaluronate (SH) were studied through rheology and DSC experiments. The results are discussed in terms of changes in the polymer conformation, structure of the network and hydration properties. This study is also aimed at controlling the viscosity of the aqueous mixturesfor application in green formulations to be used as fracturing fluids for shale gas extraction plants.

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In this work, carbon black (CB) is added in small amounts (3−10% w/w) to green aqueous dispersions based on sodium oleate, guar gum, sodium hyaluronate, or hydroxypropyl cellulose gels to enhance their stability against mechanical and thermal stresses and to provide electric responsiveness to an external voltage. Rheology, optical microscopy, small angle X-ray scattering, and conductivity measurements are performed to compare the properties of CB-enriched formulations to those of pristine dispersions. Our results demonstrate that even small amounts of CB are able to confer interesting physicochemical properties to these formulations: a remarkable increase in the viscosity of at least 1 order of magnitude is observed for all systems even at high temperature (up to 60 °C) upon CB addition, indicating that carbonaceous particles play a structuring role for the polymeric network. Furthermore, the application of an external voltage of 30 V for 60 min to CB-containing formulations imparts a significant electric responsiveness to the systems, allowing the modification of their rheological behavior. The CB-loaded formulations can be recycled at least three times. All these results suggest that CB can be effectively used as an alternative green additive to enhance the mechanical and thermal stabilities of the formulations and that its addition can be a feasible way to easily tune the properties of viscoelastic materials, thereby avoiding the use of toxic or potentially dangerous chemicals. The possibility of achieving remote control of mechanical and thermal properties of viscoelastic formulations significantly expands the horizon of their potential applications, for example, in the field of shale gas extraction.

The addition of azorubine to a viscoelastic aqueous dispersion of sodium oleate (NaOL, 0.43 M, 13% w/w) and KCl (up to 4% w/w) leads to a green gel-like system whose rheological behavior can be efficiently and reversibly triggered from remote by using UV light. Rheology, Differential Scanning Calorimetry (DSC) measurements and phase behavior studies indicate that the original texture of the NaOL dispersion is significantly hardened upon UV irradiation for 8 hours in the presence of azorubine, showing a seven hundred-fold increase in viscosity. The UV treatment brings about the trans to cis isomerization of azorubine, which modifies the structure of the NaOL wormlike micellar system, leading to a more entangled, close-textured network. The cooperative effect of KCl on the fluid viscosity is found to be concentration-dependent. The system slowly reverts to its original rheological behaviour after standing for about 1 day. These results are relevant for the development of stimuli-responsive innovative systems based on biocompatible, non expensive and commercially available materials that can be used in a wide range of applications, such as in drug delivery or enhanced oil recovery, where a quick change in the physico-chemical features of the system is required but difficult to be performed.