Poly solubility behavior

The advantage of the activated displacement polymerization is the facile incorporation of different and unconventional structural units in the polymer backbone. Most of the heteroarylene activated polyethers prepared by this route are soluble in many organic solvents. The solubility behavior of new polyethers is shown in Table 8. In contrast to many polyphenylenequi-noxalines, poly(aryl ether phenylquinoxalines) prepared by the quionoxaline activated displacement reaction are soluble in NMP. Solubility in NMP is important since it is frequently used for polymer processing in the microelectronics industry [27]. 

The acetyl group content of the polymer is compared with that of the original poly(vinyl acetate), and the solubility behavior is also examined. 

Poly[o-phthalaldehyde] was reported to be soluble in organic solvents, in contrast with isotactic polyacetaldehyde. This solubility behavior afforded us a good chance to test the stereoregulating capacity of our catalyst in the polymerization process. 

The IR spectra of all three polymers are recorded and compared with one another. The incorporation of monomeric tmits of 4-vinylpyridine can also be demonstrated by nitrogen analysis of the block copolymer. The solubility behavior is also determined. Poly(4-vinylpyridine) is soluble in pyridine, methanol, and chloroform, but insoluble in toluene and diethyl ether it swells considerably in water. On the other hand, the block copolymer, like polystyrene, is soluble in pyridine, chloroform, and toluene but unlike polystyrene, it swells significantly in methanol. 

The common surfactants discussed repeatedly here and elsewhere are in general unsuitable for water-supercritical carbon dioxide emulsions of all types (including microemulsions). Selections are made, to start with, on the basis of the water/ carbon dioxide solubility behavior. A surfactant used in some of the initial studies is ammonium carboxylate perfluoropolyether [24,25]. Subsequently, a variety of triblock co-polymers, e.g. poly(propylene oxide-b-ethylene oxide-b-propylene... 

Some polymers such as poly(acrylic acid) or polyacrylamide precipitate from aqueous solutions when cooled (normal solubility behavior) whereas others such as poly(ethylene oxide), poly(propylene oxide), or poly(methacrylic acid) phase separate when heated (inverse solubility behavior). Solution turbidimetiy is often used to obtain plots of phase-separation temperatures termed cloud point vs concentration for fixed solvent conditions. Changes in ionic strength, molecular weight, and addition of co-solvents or structure breakers affect the shapes of phase behavior curves. The important conclusion of such studies is that the total free energy of the polymer and water must be considered to predict phase behavior. The structin-e and dynamics of water surroimding polynucleotides, proteins, polysaccharides, and lipids are also major determinants of biological activity (8-10). 

In Procedure 2-10 poly(methacrylic acid) is purified by using this phenomenon. In this case, since methanol is a theta solvent for the polymer near 26° C [12], the polymer is repeatedly dissolved in the cold solvent and reprecipitated by gradual warming to a temperature somewhat above 25°C. Poly(acrylic acid) is generally more soluble than poly(methacrylic acid) and may exhibit more normal temperature V5. solubility behavior in some solvents. In aqueous systems such factors as the pH of the medium and the concentration of dissolved electrolytes also influence the solubility characteristics of the polymers. 

After expression of poly(VPGXG) genes, the biopolymer can easily be purified from a cellular lysate via a simple centrifugation procedure, because of the inverse temperature transition behavior. This causes the ELPs to undergo a reversible phase transition from being soluble to insoluble upon raising the temperature above the and then back to soluble by lowering the temperature below Tt (Fig. 9). The insoluble form can be induced via addition of salt [27]. The inverse transition can... 

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