Aqueous polyethylene oxide

Fig. 4.2.11 Shear viscosity versus shear rate data for a 1 % aqueous polyethylene oxide) solution. SynT bols same as in Figure 4.2.10.

In order to illustrate the specific material properties of polymers, we compare a viscous fluid (silicone oil) with a viscoelastic shear thinning fluid (aqueous polyethylene oxide solution). These fluids are used as model fluids in order to show the flow behavior limits for polymer melts, which corresponds to the behavior of a viscous fluid at very low shear rates and to the behavior of a shear thinning fluid at very high shear rates. 

Kim MW, Cao BH (1993) Additional reduction of surface tension of aqueous polyethylene oxide (PEO) solution at high polymer concentration. Europhys Lett 24 229... 

Ullmann, et al.O ) extended Ullmann and Philhes(31) to study probe diffusion of carboxylate-modified polystyrene spheres in aqueous polyethylene oxide Triton X-100. The Dp for most sphere matrix combinations follows a stretched exponential in c, as seen in Figure 9.18. However, Dp of the 655 nm diameter spheres shows re-entrant behavior, both in the 18.5 kDa polymer and to a lesser extent... 

Most of the methods for coating the SiC matrix on the electrodes involve SiC based slurry handling. In order to maintain the slurry mixture without settling, a suitable vehicle is required. Aqueous polyethylene oxide base ink vehicle has certain advantages compared to other systems like glycols (Trocciola et al., 1977), and is used almost universally for making the matrix. 

Figure 8.5 Osmotic pressure of aqueous polyethylene oxide solutions at 20°C. (From Ref. 9.)...

Calculate the coUigative properties of aqueous polyethylene oxide solutions and compare the results with the polystyrene-toluene system data given in Table 8.1. 

COMPARISON OF FOUR COMMERCIAL LINEAR AQUEOUS SIZE EXCLUSION COLUMNS AND FOUR SETS OF COMMERCIAL POLYETHYLENE OXIDE (PEO) STANDARDS FOR AQUEOUS SIZE EXCLUSION CHROMATOGRAPHY OF POLYVINYLPYRROLIDONE AND PEO... 

Figure 1. Intrinsic viscosities for nonionic polyacrylamides in water and aqueous solutions of various pH and ionic strength ((%, 4) water (, O, m) aqueous solutions (pH range 2,5 7.0 and ionic strength range 0,013-. 503) containing a nonionic surfactant (either Tergitol or polyethylene oxide = 300,000))...

Figures 6, 7 and 9 show calibration curves using two multi-column combinations and illustrate the degree of "optimization obtained in this system. The mobile phases for Figures 6 and 7 contained 0.025 g polyethylene oxide and ion exclusion and adsorption effects should therefore be largely eliminated. Figure 6 shows that reasonably good resolution can be obtained with a combination of five columns but does exhibit some loss of peak separation at the low cuid high MW ends. In Figure 7 the effect of adding a sixth column of small pore size is illustrated and it is seen that resolution at the low MW end is thereby somewhat improved. This calibration curve is effectively linear with a change of slope at 500,000 MW. It should provide a useful aqueous GPC system for MW and MWD determination of nonionic polyacrylamides.

Fluidized aqueous suspensions of 15% by weight or more of hydroxyethyl-cellulose, hydrophobically modified cellulose ether, hydrophobically modified hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, and polyethylene oxide are prepared by adding the polymer to a concentrated sodium formate solution containing xanthan gum as a stabilizer [278]. The xanthan gum is dissolved in water before sodium formate is added. Then the polymer is added to the solution to form a fluid suspension of the polymers. The polymer suspension can serve as an aqueous concentrate for further use. 

Steric Stabilization. Steric stabilization was a term first introduced by Heller to explain how adsorbed polyethylene oxide polymers increased the salt concentration required for flocculation of negatively charged aqueous suspensions.(6) Heller s systems were stabilized by both mechanisms, as are most commercial dispersions today, aqueous and non-aqueous. Much of the more recent literature on steric stabilizers has been preoccupied with solubility requirements, for the solubility of polymers is a delicate matter and very sensitive to temperature and solvent... 

Chen Kegiang for the degradation of hydroxyethylcellulose (Fig. 5.25) and polyethylene oxide (Fig. 5.26) in aqueous solution. 

Aqueous SEC Experiments. Aqueous SEC separations were carried out at ambient temperature using two column sets of MicroPak TSK PW Type gel which were investigated for linearity of molecular weight calibration curve using polyethylene glycol (PEG) and polyethylene oxide (PEO) narrow MWD standards. Columns were matched in pore volume as closely as possible to promote linearity of the molecular weight calibration cuiA e. Column set A consisted... 

Polymer phase-transfer catalysts (also referred to as triphase catalysts) are useful in bringing about reaction between a water-soluble reactant and a water-insoluble reactant [Akelah and Sherrington, 1983 Ford and Tomoi, 1984 Regen, 1979 Tomoi and Ford, 1988], Polymer phase transfer catalysts (usually insoluble) act as the meeting place for two immiscible reactants. For example, the reaction between sodium cyanide (aqueous phase) and 1-bromooctane (organic phase) proceeds at an accelerated rate in the presence of polymeric quaternary ammonium salts such as XXXIX [Regen, 1975, 1976]. Besides the ammonium salts, polymeric phosphonium salts, crown ethers and cryptates, polyethylene oxide), and quaternized polyethylenimine have been studied as phase-transfer catalysts [Hirao et al., 1978 Ishiwatari et al., 1980 Molinari et al., 1977 Tundo, 1978]. 

Water-dispersible polyisocyanate compositions containing polyethylene oxide were previously prepared by the authors (2) and used as aqueous resin adhesives. 

Figure 6. Effect of thiourea on decay of radicals in aqueous solutions of polyethylene oxide. Time after pulse in fisec. Broken line is decay in PEO radicals. Solid line is decay when thiourea is present. Dose about 5000 rads.

Au NPs have been synthesized in polymeric micelles composed of amphiphilic block copolymers. Poly(styrene)-block-poly(2-vinylpyridine) in toluene has been used as nanocompartments loaded with a defined amount of HAuCl4 and reduced with anhydrous hydrazine. The metal ions can be reduced in such a way that exactly one Au NP is formed in each micelle, where each particle is of equal size between 1 and 15 nm [113]. In another example, the addition of HAuCfi to the triblock copolymer (PS-b-P2VP-b-PEO) (polystyrene-block-poly-2-vinyl pyridine-block-polyethylene oxide) permits the synthesis of Au N Ps using two different routes, such as the reduction of AuC14 by electron irradiation during observation or by addition of an excess of aqueous NaBH4 solution [114]. 

Alexandridis P, Hatton TA. Polyethylene oxide)-poly(propylene oxide)- poly(ethylene oxide) block copolymer surfactants in aqueous solutions and at interfaces thermodynamics, structure, dynamics, and modeling (review). Colloid Surf A Physicochem Eng Aspects 1995 96 1 16. 

Finally, it might be noted that colloids may be concentrated by a slight modification of the dialysis procedure. The liquid against which the colloid of interest is being dialyzed may itself be a concentrated colloid. With aqueous dispersions, for example, polyethylene oxide solutions may be used as the second colloid. 

PGSE measurements on polyethylene oxide) in aqueous dextran solutions were performed by Brown and Stilbs A2) as function of the concentrations of both polymers. The results for D(PEO) depend on the product of the concentration and the intrinsic viscosity of the dextran (host) component, and suggest that coil overlap in the concentrated host solution is the principal impediment to PEO diffusion. 

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