Interfacial Behavior of Aqueous Two-Phase Systems Based on Linear and Hyperbranched Polymers

Abstract

In this work, the interfacial behavior of two different aqueous two-phase systems (ATPSs) was analyzed. One ATPS is formed by the dissolution of polyethylene glycol (PEG) and dextran T40 in water, and the second ATPS is formed by a hyperbranched polyesteramide (HB) and dextran T40. The interfacial behavior of both ATPSs was investigated experimentally and theoretically. As a thermodynamic model, the lattice cluster theory combined with a lattice Wertheim model was used. This thermodynamic model was combined with density gradient theory to model the interfacial properties. It was found that the interfacial tension, which was measured by the spinning drop method, of the ATPS containing the HB was lower than the interfacial tension of the ATPS containing the PEG. Moreover, the mass transfer of the phase forming components across the interface was measured and modeled. To measure the mass transfer, a Nitsch cell was used. The mass transfer was modeled by the instationary density gradient theory. It was found that the mobility coefficient of dextran could be transferred from one system to the other one.

Mass Transfer of Proteins in Aqueous Two-Phase Systems

“…Regarding the interfacial tension the one of the ionic liquid is with 7.5 mN m −1 about 60 times larger compared to the PEG/citrate ATPS without NaCl (0.125 mN m −1 ) 26 and about 25 times larger compared to the same ATPS with exemplary 4 wt.-% NaCl (0.300 mN m −1 ). For the PEG8000/Dextran system a 125 times smaller interfacial tension of 0.060 mN m −1 was determined compared to the ionic liquid system 28 . Although the kinematic viscosity and the interfacial tension of the water ionic liquid system differs significantly to that of the PEG/Dextran system, the k -values determined were in the same range, as the molecular weight of the amino acid and the cyclic ketone were similar.…”

Enrichment at vapour–liquid interfaces of mixtures: establishing a link between nanoscopic and macroscopic properties

“…The present work is limited to the investigation of vapour-liquid interfaces of binary mixtures of molecular fluids. Related work on electrolyte solutions and ionic liquids [2,[37][38][39][40][41][42][43], on the behaviour of surfactants at interfaces [44][45][46][47][48][49], as well as on the enrichment of components at liquid-liquid interfaces [27,31,33,[50][51][52][53][54] is not covered. Since theoretical methods for the prediction of component density profiles, namely molecular simulation, DGT, and DFT have been reviewed in detail elsewhere [55][56][57][58][59] their description is not subject of the present paper.…”

Liquid‐Liquid Equilibrium and Interfacial Properties of the System Water + Hexylacetate + 1‐Hexanol

“…Such a theoretical framework, which permits the calculation of the interfacial tension related to the LLE was established twenty years ago [7]. The basic idea of this approach is the applica-tion of the density gradient theory, originally developed by Van der Waals [8] and rediscovered by Cahn-Hilliard [9], to incompressible fluids, where the Helmholtz energy can be replaced by the Gibbs energy and consequently the thermodynamic properties can be modelled with a g E model rather than an equation of state [10,11] The method was used for different binary [12][13][14][15][16][17][18][19][20][21], ternary [14,21,[22][23][24][25][26] and quaternary mixtures [21,[27][28][29]. Recently, also the time-dependency of the interfacial tension caused by diffusion [14,16,24,27] or caused by a chemical reactions [21,29] were studied.…”

“…Ternary mixtures showing this phase behavior have a critical point, where the interfacial tension is zero. For these mixtures, the interfacial tension could be predicted based on data of the bulk‐phase diagram and one value for the interfacial tension in the binary subsystem , , , . For ternary mixtures, where two binary subsystems exhibiting a miscibility gap only one paper dealing with the prediction of interfacial properties for the mixture water + 1‐butanol + benzene is available in the literature.…”