Polar dissolvent dimethylacetamide

These results confirm the observation that polyelectrolyte aqueous solutions show two separate decay modes in the autocorrelation function and support our contention that ionic polymer systems generally behave similarly in polar solvents [23], To support this, it may be added that similar dynamic scattering behavior was recently reported for another type of ionomer, polyurethane ionomer, dissolved in a polar solvent, dimethylacetamide (e = 38) [92], Finally, it should be stressed that the explanation given above for light scattering (both static and dynamic) behavior of salt-free polyelectrolytes is based on the major role of intermolecular electrostatic interactions in causing characteristic behavior. No intramolecular interactions are explicitly included to explain the behavior. This is in accord with our contention that much of the polyelectrolyte behavior, especially structure-related aspects, is determined by intermolecular interactions [23]. 

The Japanese researchers report [ 175-179] on the syntheses of aromatic polysulfones via the method of polycondensation in the environment of polar dissolvent (dimethylformamide, dimethylacetamide, and dimethylsulfoxide) at 60-400 °C in the presence of alkali metal carbonates within 10 min to 100 h. The s mthesized thermoplastic polysulfones possess good melt fluidity [175]. 

Resin and Polymer Solvent. Dimethylacetamide is an exceUent solvent for synthetic and natural resins. It readily dissolves vinyl polymers, acrylates, ceUulose derivatives, styrene polymers, and linear polyesters. Because of its high polarity, DMAC has been found particularly useful as a solvent for polyacrylonitrile, its copolymers, and interpolymers. Copolymers containing at least 85% acrylonitrile dissolve ia DMAC to form solutions suitable for the production of films and yams (9). DMAC is reportedly an exceUent solvent for the copolymers of acrylonitrile and vinyl formate (10), vinylpyridine (11), or aUyl glycidyl ether (12). 

In GPC, the solvent in which the standards and sample are dissolved should be identical to the mobile-phase solvent in which the analysis will be performed. In most cases filtration is the only step needed to prepare the mobile phase. Organic solvents should be vacuum filtered through a 0.45-pm fluorocarbon filter, while acetate-type filters are used with aqueous mobile phases. In some cases mobile-phase additives are required. When polar solvents such as N,N-dimethyformamide, N,N-dimethylacetamide, and -methyl pyrrolidone are used to analyze polar polymers such as poly-... 

Cellulose can also be dissolved by the action of formaldehyde in pyridine, iViV-dimethylfonnamide, iViV-dimethylacetamide, A/-methyl-2-pyrrolidone, and thiolane 1-oxide. These solvents have the common characteristics of being polar, aprotic, and good hydrogen-bond acceptors. Interaction of the solvent with formaldehyde appears to be important in these systems in order to enhance the retention of formaldehyde in solution and maintain it in a highly active state. 

The practical applications of fluoropolymer membranes especially in the areas of purification and separation related to potable water production, wastewater treatment and bioprocessing, have been limited to some extent by their hydrophobic and inert surface properties. Among the different modification techniques, graft copolymerization of hydrophilic monomers, or inimers for further surface reactions, from fiuoropolymers has been useful and effective in improving the physicochemical properties of the parent fluoropolymer with minimum alteration of their desirable bulk properties. Apart from fiilly fluorinated polymers, most of the partially fluorinated polymers can dissolve in polar organic solvents, such as Ai,Ai-dimethylformamide (DMF), A,A-dimethylacetamide (DMAc), NMP, and dimethyl sulfoxide (DMSO), but are insoluble in water, alcohols, and hydrocarbons. 

The resistance of poly (vinylidene fluoride) to solvents and chemicals is generally good but inferior to that of polytetrafluoroethylene and polychlorotri-fluoroethylene. Some highly polar solvents such as dimethylacetamide dissolve the polymer at elevated temperature whilst organic amines cause discoloration and embrittlement. Fuming sulphuric acid leads to sulphonation. 

Good solvents for PBl are polar aprotic solvents such as iV,A/-dimethylacetamide (DMAc), A -methyl-2-pynolidOTie (NMP) or dimethylsulfoxide (DMSO), and strmig protic acids like phosphoric acid, sulfuric acid (risking sulfonation reactions), or methylsulfonic acid. In order to dissolve PBl in organic solvents, great care must be taken to remove all phosphoric acid traces from the polymer, since it strongly hinders dissolution in DMAc. 

It swells in certain polar solvents like ketones and esters and dissolves in aprotic solvents like dimethylacetamide, dimettiylformamide and N methylpyrrolidone. It is also attacked by hot amines. 

The operations used to either wet- or dry-spin acrylics are essentially the same as those already described for rayon and acetate, respectively. The polymer must be completely dissolved in solvent and the solution filtered to remove any impurities that would cause spinnerette blockage. Because acrylic polymers are not soluble in common nonpolar solvents, polar substances such as dimethylfonnamide, dimethylacetamide, or aqueous solutions of inorganic salts such as zinc chloride or sodium thiocyanate are required. Only wet spinning is possible with the latter. Dimethyl formamide boils at 152.8°C and exerts a vapor pressure of 3.7 mm of Hg at 25°C compared with acetone (used in dry spinning of cellulose acetate), which has a vapor pressure of 228.2 mm of Hg at 25 C. It follows that, unlike acetone which requires an activated-carbon system for recovery, dimethylformamide may be condensed directly from the gas stream... 

Intravascular catheter is used for providing central venous nutrition and performing dialysis treatment. Antimicrobial layers may be formed with an antimicrobial agent such as antibiotic coated on the surface. The antimicrobial agent may be continually released from the surface while inside the body. Most antibiotics are very polar and do not dissolve in organic solvents. Aprotic polar solvents, such as dimethylformamide, dimethyl sulfoxide, dimethylacetamide, 2-butanone, acetone, acetinitrile, and N-metiiylpyrrolidone are useful in this application. ... 

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