Solutions of water soluble polymers

Surface sizes are usually solutions of water-soluble polymers. The most important of which, because of its commercial cheapness, is starch. Other more costly but more specialised film-forming polymers such as soluble cellulose derivatives (particularly carboxy-methyl cellulose), polyvinyl alcohol and alginates are also used. 

Therefore, methods of stabilizing dispersions against water injection (e.g., use of other surfactants, lamellar liquid crystals, use of very dilute solutions of water-soluble polymers with surfactants) might aid commercialization by reducing surfactant costs. 

The Kirkwood-Buff theory of solutions for ternary mixtures was used to analyze the gas solubility in a mixed binary solvent composed of a high molecular weight and a low molecular weight cosolvent, such as the aqueous solutions of water soluble polymers. A rigorous expression for the composition derivatives of the gas activity coefficient in ternary solution was used to derive the composition dependence of the Henry constant under isobaric and isothermal conditions. The obtained expressions as well as the well-known Kri-chevsky equation were tested for the solubilities of Ar, CH4, C2H6 and C3H8 in the aqueous solutions of PPG-... 

Walden s rule. However, this rule is obeyed in rare cases mainly in some mixed aqueous-organic solutions is an acceptable agreement found. On the other hand, in very viscous aqueous solutions of water-soluble polymers, such as poly(ethylene glycol), it was found that the actual mobility is independent of the viscosity. 

Champ S, Xue W, Huglin MB (2000) Concentrating aqueous solutions of water soluble polymers by thermoreversible swelling of polyr(W-isopropylacrylamide)-co-(acrylic acid) hydrogels. Macromol Chem Phys 201 931-940... 

In this process, an aqueous solution of a water-soluble monomer (e.g., acrylamide) is dispersed in an organic continuous phase using an excess of surfactant. Water-in-oil micelles are formed. The polymerization is initiated by oil-soluble initiators, and the mechanisms involved in this process are similar to those occurring in emulsion polymerization. The product is a dispersion of an aqueous solution of water-soluble polymer in an organic... 

Simple Coacervation. Aqueous solutions of water-soluble polymers are phase-separated in aqueous media when sufficient salt is added to such solutions. This phenomenon is called simple coacervation. As long as phase separation produces a liquid polymer-rich phase, simple coacervation can be used to produce microcapsules (5). Microcapsules with a gelatin or poly(vinyl alcohol) shell have been formed in this manner. The use of poly(vinyl alcohol) as a capsule shell material is of great interest in various applications because it is a widely available synthetic polymer with excellent oxygen and oil barrier properties (see Barrier Polymers Vinyl Alcohol Polymers). 

Many synthetic polymers are soluble only in organic (nonpolar) solvents. However, concern for sustainable development provides a strong interest in environment-friendly processes and formulations that exploit the extensive properties of aqueous solutions of water-soluble polymers. Recently, growing research in the domain of water-soluble polymers and their supramolecular assemblies has been strongly motivated by the applications in the emerging domains of biomaterial engineering and nanomedicine. 

In order to explain the experimental phase diagrams of water-soluble polymers, a number of semiempirical approaches that assume the concentrational dependence of the Flory-Huggins solubility parameter were developed. " " Hie two-state models, which involve equilibtium coexistence of two interconvertible (solvophilic and solvophobic) states of the monomer units, as well as the n-duster model, which assumes temperature-dependent inversion of the higher order virial coeffident, allow to rationalize the apparent concentrational dependence of the solubility parameter in aqueous solutions of water-soluble polymers. 

The end-use applieations of water-soluble polymers require aeeurate means to eharaeterize the moleeular weight distribution (MWD) and to provide a better understanding of produet performanee. The moleeular weight affeets many physieal properties sueh as solution viseosity, tensile strength, bloek resistanee, water and solvent resistanee, adhesive strength, and dispersing power. Commereially available polymers sueh as poly(vinyl aleohol). 

VI. MECHANISM OF INTERACTION OF WATER-SOLUBLE POLYMERS WITH IONS IN AQUEOUS SOLUTION... 

The qualitative thermodynamic explanation of the shielding effect produced by the bound neutral water-soluble polymers was summarized by Andrade et al. [2] who studied the interaction of blood with polyethylene oxide (PEO) attached to the surfaces of solids. According to their concept, one possible component of the passivity may be the low interfacial free energy (ysl) of water-soluble polymers and their gels. As estimated by Matsunaga and Ikada [3], it is 3.7 and 3.1 mJ/m2 for cellulose and polyvinylalcohol whereas 52.6 and 41.9 mJ/m2 for polyethylene and Nylon 11, respectively. Ikada et al. [4] also found that adsorption of serum albumin increases dramatically with the increase of interfacial free energy of the polymer contacting the protein solution. 

The hydrophobic interaction results in the existence of a lower critical solution temperature and in the striking result that raising the temperature reduces the solubility, as can be seen in liquid-liquid phase diagrams (see Figure 5.2a). In general, the solution behaviour of water-soluble polymers... 

Graft copolymers and other polymers are prepared in a way that is common in polymerization techniques [1894]. For example, they are made by providing a foamed, aqueous solution of water-soluble monomeric material, initiating polymerization by adding an initiator, exothermically polymerizing... 

A theoretical prediction of water-soluble polymer solutions is difficult to obtain due to their ability to build up aggregations and associations. A prediction of the viscosity yield is much easier to observe for solutions of synthetic polystyrene due to its simple solution structure. These solutions have been well characterized in other studies [19-23] concerning their chemical composition, molar mass and sample polydispersity. 

Adsorption behavior and the effect on colloid stability of water soluble polymers with a lower critical solution temperature(LCST) have been studied using polystyrene latices plus hydroxy propyl cellulose(HPC). Saturated adsorption(As) of HPC depended significantly on the adsorption temperature and the As obtained at the LCST was 1.5 times as large as the value at room temperature. The high As value obtained at the LCST remained for a long time at room temperature, and the dense adsorption layer formed on the latex particles showed strong protective action against salt and temperature. Furthermore, the dense adsorption layer of HPC on silica particles was very effective in the encapsulation process with polystyrene via emulsion polymerization in which the HPC-coated silica particles were used as seed. 

In this study, adsorption behavior of water soluble polymers and their effect on colloid stability have been studied using polystyrene latices plus cellulose derivatives. As the aqueous solution of hydroxy propyl cellulose(HPC) has a lower critical solution temperature(LCST), near 50 °C(6 ), an increased adsorption and strong protection can be expected by treating the latices with HPC at the LCST. 

Water-based solvent systems originally developed for the separation and purification of proteins and other biomaterials (Walter et al., 1985) have been suggested for the treatment of contaminated aqueous waste-streams. Certain pairs of water-soluble polymers are incompatible in solution together, and this can lead to phase separation in which two phases are formed. Both phases are predominantly water, and each contains only one of the two polymers. Similar phase behavior results with some polymers and high concentrations of organic salts. The properties of the two phases ensure that the environment-afforded targeted species is different in the two phases. 

We have used the uncharged polysaccharide dextran as a model describing the behaviour of water-soluble polymers. The dextrans used in this study have about 95 % oc-(l - 6) linkages within the main chain and side chains the 5 % non-a-(l -> 6) linkages are starting points of branched chains of which most are only stubs of about two glucose units 9). Therefore, while there is some branching in dextran, albeit low, its solution behaviour is that of a linear, random-coil molecule l0,ll). 

The dispersion effect of water-soluble polymers on a heme aggregate is mentioned below. However, these water-soluble polymers have no coordinating ability and are not polymer ligands. It is well known that heme and its complexes easily aggregate in aqueous solution by stacking interaction, and that stable monomeric dispersed heme complexes are formed under restricted conditions such as extremely low concentration and low ionic strength21,22 ... 

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