Polymer-water systems, phase diagram

Besides the l.c. phases, the phase diagram of the p-l.c./water is very similar to the diagram of the m-l.c./water. The broad miscibility gap of the polymer/water system shows a lower critical consolute point, which is shifted to lower concentrations (3.2% of polymer). This is consistent with experiments and theory on the position of miscibility gaps in polymer solutions112). 

Karlstrom, G. Carlsson, A. Lindman, B., "Phase Diagrams of Nonionic Polymer-Water Systems. Experimental and Theoretical Studies of the Effects of Surfactants and Other Cosolutes," J. Phys. Chem., 94, 5005 (1990). 

Di erent polymer-solvent systems may have completely different phase diagrams. For some systems, such as polystyrene-cyclohexanone, UCST < LCST [Fig. 3.13(a)] but for others, e.g., highly polar systems like polyoxyethylene-water, UCST > LCST and closed solubility loop is found [Fig. 3.13(b)]. 

Figure 4.9 Phase diagram of the system water-decane-CioE4 at equal volume fractions of water and decane as a function of the temperature T and the surfactant concentration cf>7. At low (f>7 there is a three-phase coexistence, while at moderate cf>7 the one-phase bicontinuous microemulsion appears. At even higher cf>7 the lamellar phase appears. At high and low temperatures a microemulsion phase coexists with either excess water or oil. The polymer fraction cf>p is raised symmetrically for the water- and oil-soluble polymers, and the one-phase microemulsion window closes continuously. The 2 K temperature shift is due to the use of heavy water. (From Ref. [40], reprinted with permission of the American Chemical Society.)...

Figure 4.11 Scheme of a phase diagram of the system water-isooctane-AOT-PEO with the polymer content Cp as a function of the aqueous phase water content Xwp- L2 is the w/o-droplet phase in the region 2 a microemulsion coexists with an aqueous phase al specifies a solid polymer coexistence with a microemulsion in the region t2 solid polymer, aqueous polymer solution and a microemulsion are found. The real phase diagram with more phase regions is found in [52]. (From Ref. [52], reprinted with permission of the American Chemical Society.)... 

Figure 4.12 Phase diagram of the system water-isooctane-AOT-PEO as a function of the temperature T and the surfactant concentration y. The isooctane content was fixed at 40wt.% and the polymer content in the aqueous phase was either Cp = 5 or 20 wt.%. The phase regions are 2 for microemulsion coexisting with excess water, 2 for microemulsion coexisting with excess oil, 3 for three-phase coexistence of a microemulsion with two excess phases. Inside the fish-tail there are one-phase regions L Li for o/w-droplet microemulsions, L2 for w/o-droplet microemulsions, La for the lamellar phase and 2a for a coexistence of a lamellar with a microemulsion phase. Note that the whole fish-tail is shifted to higher surfactant concentrations upon polymer addition. (From Ref. [53], reprinted with permission of the American Chemical Society.)...

Figure 22.2. Phase diagram of water at low temperature. Note the no-man s-land between and Tx. This region can only be accessed by restricting the crystallization. An example of such a system is water in a nanotube. Note the extended HDA/LDA first-order phase transition line into the no-man s-land region which ends in a critical point denoted by the dot at the end of the Une. At atmospheric pressure if one decreases the tempemture, then the region beyond the eritieal point is accessed. The figure is reproduced from the thesis of Dr. Pradeep Kumar, http //polymer.bu.edu/ hes/water/thesis-kumar.pdf.

State diagrams of polymer/water systems of which the polymer is water sensitive essentially seem to be of the eutectic type known from low molecular binary systems but including some peculiarities caused by non-equilibrium phenomena and incomplete phase transitions. The... 

Karlstrom G, Carlsson A, Lindman B (1990) Phase diagrams of nonionic polymer -water systems. Experimental and theoretical studies of the effects of surfactants and other cosolutes. J Phys Chem 94 5005-5015... 

It can be noticed from Figure 11.4 that the mutual solubilities of ionic liquids and water are not symmetric. Generally, a much higher mole fraction of water is present in the ionic liquid phase than ionic liquid present in the water phase at the same temperature. The UCST is thus found at very low fractions of the ionic liquid. This asymmetry is also observed in (polymer + water) systems. Therefore, there are analogies between the phase diagrams of ionic liquid solutions and polymeric ones, although this may be due to different mechanisms. 

POL Polyakov, V.I., Grinberg, V.Ya., and Tolstoguzov, V.B., Application of phase-volume-ratio method for determining the phase diagram of water-casein-soybean globulins system, Polym. Bull, 2, 757,1980. 

Polyakov, V. L, Grinberg, V. Ya, Tolstoguzov, V. B. (1980). Application of Phase-Volume Ratio Method for Determining the Phase Diagram of Water-Casein-Soybean Globulins System. Polymer Bulletin, 2,160-161. 

The basis for the separation is that when two polymers, or a polymer and certain salts, are mixed together in water, they are incompatible, leading to the formation of two immiscible but predominantly aqueous phases, each rich in only one of the two components [Albertsson, op. cit. Kula, in Cooney and Humphrey (eds.), op. cit., pp. 451 71]. A phase diagram for a polyethylene glycol (PEG)-Dextran, two-phase system is shown in Fig. 22-85. Proteins are known to distribute unevenly between these phases. This uneven distribution can be used for the selective concentration and partial purification of the products. Partitioning between the two phases is controlled by the polymer molecular weight and concentration, protein net charge and... 

The system polyethylene glycol (PEG)-dextran-water is still the most used and best-studied aqueous polymer two-phase system. A phase diagram for a typical two-phase system is shown in Fig. 10.12 for the PEG-dextran system. Both polymers are separately miscible with water in all proportions. As the polymer concentration increases, phase separation occurs, with the... 

Diphasic liquid systems used in CCC may have a wide variety of polarities. The most polar systems are the ATPS made by two aqueous-liquid phases, one containing a polymer, for example, polyethylene glycol (PEG), the other one being a salt solution, for example, sodium hydrogen phosphate. The less polar systems do not contain water there can be two-solvent systems, such as heptane/acetonitrile or dimethylsulfoxide/hexane systems or mixtures of three or more solvents. Intermediate polarity systems are countless since any proportion of three or more solvents can be mixed. Ternary phase diagrams are used when three solvents are mixed together. 

FIG. 8.13 Two representations of a portion of the phase diagram for the water-benzene-potassium oleate-pentanol system. The unshaded regions represent homogenous solutions, (a) Redrawn, with permission, from S. Friberg and I. Burasczeska, Prog. Colloid Polym. Sci., 63, 1 (1978). (b) Redrawn, with permission, from C. U. Herrmann, U. Wurz, and M. Kahlweit, In Solution Chemistry of Surfactants, Vols. 1 and 2 (K. L. Mittal, Ed.), Plenum, New York, 1979. 

First, it is necessary to establish the phase diagram of the aqueous two-phase system formed by water and two water-soluble polymers. Second, a method must be established for calculating the distribution coefficient of a biomolecule that partitions between the two aqueous phases. A simple molecular-thermodynamic description is provided by the osmotic virial... 

This polymer is spun from a solution in pure (100%) sulphuric acid. A typical, but too simple phase diagram for the PpPTA-sulphuric acid/water system is shown in Fig. 19.24 (also shown as Fig. 16.27). It shows that the solution is solid at sulphuric acid/water ratio smaller than approximately 0.95 liquid solutions are obtained at high sulphuric acid contents at low polymer concentrations isotropic solutions are obtained whereas at higher polymer concentrations the solutions are anisotropic. It is clear that for solution spinning almost pure sulphuric acid or even oleum (i.e. H2SO4... 

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