Heat of mixing and liquid–liquid-equilibrium of water + polypropylene glycol (PPG) with different molecular weights and water + propylene glycol dimethyl ether

Aqueous Biphasic Systems as a Suitable Route to Remove and Concentrate Parabens from Aqueous Media

“…Comparing the different PEG studied, the greater the molecular weight, the lower the solubility in water, favoring the ABS formation. − As can be seen in Figure , for example, PEG 400 requires a large amount of salt to achieve the biphasic region. The PEG-based ABSs are extensively reported in the literature as a suitable method of separation and purification of several compounds. ,− For some applications, the PPG presents some advantages concerning the more hydrophobic character, resulting from an additional methyl group per monomer, compared to PEG, being more suitable to separate or concentrate low hydrophilic compounds. − The interest in this polymer is due to the high hydrophobicity conferred to it, resulting in an additional methyl group per monomer, compared to PEG. This characteristic confers a more hydrophobic character to PPG than PEG, even in low molecular weights. , …”

“…This characteristic confers a more hydrophobic character to PPG than PEG, even in low molecular weights. 55,56 Therefore, considering the characteristics of both evaluated polymers, the ability to obtain biphasic regions increases with their hydrophobicity because of the incompatibility between the system's components. As shown in Figure 2, in the systems under study, the ability to promote two phases followed the order: PPG 400 > PEG 6000 > PEG 2000 > PEG 400.…”

Acrylamide-induced enhanced solubilization of poly(propylene glycol) in aqueous solution

“…Consequently, there are very limited research studies exploring the phase behavior of PPG aqueous solution. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In fact, low molecular weight PPG can be dissolved in water well and the lower critical solution temperature (LCST) type behavior of PPG aqueous solution has been reported for a long time. 6 When the temperature exceeds a critical value named the cloud point, a clear PPG aqueous solution becomes turbid.…”

“…Like other LCST-type polymers, the cloud point decreases with an increase in the concentration and molecular weight of PPG. [6][7][8][9][10] In addition, some additives can also affect the cloud point of PPG aqueous solution. A salting out effect can be induced by most inorganic salts [10][11][12][13][14] and ionic liquids 15 following the Hofmeister series.…”

Methodology to Predict Thermodynamic Data from Spectroscopic Analysis

“…Recently, the use of isothermal calorimetry (ITC) for the generation of thermodynamic parameters has been (re-)evaluated and reported. [2][3][4][5][6][7][8] This methodology, sometimes in combination with molecular modeling, showed some success in the prediction of solid−liquid equilibrium, 2 liquid−liquid equilibrium, 3 solvent selection for extraction 4,5 and extractive distillation processes, 6,7 and in describing solvent interactions. However, for studies on acid−amine interactions thermodynamic parameters obtained from ITC measurements appeared to be concentration dependent, restricting their use to the evaluated concentration range only.…”