Chloroform polystyrene

To illustrate the application of corresponding-states theory to polymer solution calculations, we consider two cases of sol-vent/polymer vapor-liquid equilibria. The first case we consider is that of the chloroform/polystyrene solution. The second is that of benzene/polyethylene oxide. 

The chloroform/polystyrene solution exhibits highly nonideal behavior. As shown by curve C in Figure 4, the x parameter for this solution rises from a low value to a high value as solvent concentration increases. However, as shown in Figure 5, the partial pressure of chloroform above a mixture of... 

Geveke, D.J. Danner, R.P., "Application of the Flory-Huggins Theory to the System Chloroform-Polystyrene-Butadiene Rubber," Polym. Eng. Sci., 31, 1527 (1991). 

Figures 13.25-13.28 show the ultrahigh resolution separations in chloroform of polystyrene standards, polytetramethylene glycol, urethanes and isocyanates, and epoxy resins, respectively. Multiple column sets of anywhere from two to six columns in series have been used for well over a year with no apparent loss of efficiency. The 500- and 10 -A gels can easily tolerate 15,000 psi or more. In fact, the limiting factor in the number of columns that can be used in series is generally the pump or injector in the FIPLC system. A pump capable of 10,000 psi operation should allow the use of a column bank of 10-12 50-cm columns with a total plate count of 500,000 or more.

FIGURE 13.25 Using chloroform as the solvent, a mixture of polystyrene standards were nicely separated on the 3-m set of columns. Run times here were 160 min. Plate count for toluene was calculated at 240,000 plates. The 500 MW Standard is separated nicely into its oligomers. 

As the porosities of PDVB gels increase above 10 A, the pressure limits drop, with 2500 psi being the maximum usable pressure for 10 A, 10 A, and mixed-bed columns. Because the normal operating pressures in most solvents for these columns tend to be in the range of 1000 psi or less for a 10 X 500-mm column, there is seldom an operational problem. Figure 13.8 shows the resolution of a typical mixed-bed column run in chloroform at 1.5 ml min yielding a back pressure of 700 psi and running polystyrene standards. 

FIGURE 15.3 Column No. 2. Calibration dependences for polystyrenes in THF ( ), chloroform (9), and toluene C ) eluents. Samples were dissolved in eluent. 

Linear non-cross-linked polystyrene has been used for organic synthesis since it is readily soluble in common organic solvents (i.e., dichloromethane, chloroform, tetrahydrofuran, toluene, ethyl acetate, and pyridine) but precipitates upon addition of water or methanol [123-126]. However, no examples of the use of this polymer in conjunction with microwave chemistry have been reported. 

Methyl chloride-polystyrene, 56, 96 Methyl chloroformate, 59,195 Methyl (chlorosulfonyl)carbamate, 56,40 Methyl cyanoacetate, 56, 63 Methyl 2-(l-cyanocyclohexyl)diazene-carboxylate, 58, 102, 106... 

Illustrative Procedure 2 Poly(iminocarbonates) by Solution Polymerization (46) Under argon, 1 g of a diphenol and an exact stoichiometric equivalent of a dicyanate were dissolved in 5 ml of freshly distilled THF. 1 mol% of potassium tert-butoxide was added, and the reaction was stirred for 4 hr at room temperature. Thereafter, the poly(iminocarbonate) was precipitated as a gumUke material by the addition of acetone. The crude poly(iminocarbonate) can be purified by extensive washings with an excess of acetone. The molecular weight (in chloroform, relative to polystyrene standards by GPC) is typically in the range of 50,000-80,000. 

Fig. 49.—Reciprocal of the sedimentation constant s plotted against concentration for two polystyrene fractions in chloroform. Molecular weights 13X10 and 5.5X10 for fractions 1 and 19, respectively. (Newman and Eirich. )...

The homopolymers of styrene and acrylonitrile were not soluble In the acetonitrile mobile phase. Calibration factors thus had to be derived from a combination of literature data and experimental measurements. To calibrate the UV detector for polystyrene, 254 nm absorbance of both monomer and polymer was measured with a conventional spectrophotometer, using chloroform... 

Molecular weights of the copolymers were determined by gel permeation chromatography (GPC) with four p-styragel (Haters) columns calibrated using polystyrene standards. Chloroform was used as the eluate at a flow rate 1.5 ml/min. An LKB-2140 Ultraviolet Photodiode Array detector was used to detect the polymer with a scan range from 190 to 370 nm. 

Conjugated boron polymers containing platimnn or palladium atom in the main chain were also prepared by hydroboration polymerization between tetrayne/ metal complex monomers and tripylborane (scheme 16).30 From gel permeation chromatographic analysis [THF, polystyrene (PSt) standards], the number-average molecular weights of the polymers obtained were found to be 9000. The polymers were soluble in common organic solvents such as THF, chloroform, and benzene. The absorption peaks due to tt-tt transition were observed around 390 nm in the UV-vis spectra of these polymers. The fluorescence emission spectra exhibited intense peaks at 490 nm in chloroform. 

Giordano, M. Russo, M. Cusano, A. Cutolo, A. Mensitieri, G. Nicolais, L., Optical sensor based on ultrathin films of 5 form syndiotactic polystyrene for fast and high resolution detection of chloroform, Appl. Phys. Lett. 2004, 85, 5349... 

The present procedure2 describes the conversion of resin-bound, primary aliphatic amines into isothiocyanates and the conversion of the latter into 3-aminothiophenes. The generation of isothiocyanates is related to known procedures,3 in which amines are first treated with carbon disulfide and the resulting dithiocarba-mates are desulfurized by treatment with a condensing agent (alkyl chloroformates, carbodiimides, lead or mercury salts, etc.). The presence of resin-bound isothiocyanates on the polystyrene support could be qualitatively ascertained by infrared spectroscopy (KBr-pellet strong absorption at 2091 cm-1). 

Analytical procedures The molecular weights of the polyisobutylenes (Systematic name poly(l,l-dimethylethylene) and of the polynorbornadienes (Systematic name poly(3,5-tricyclo[2.2.1.02, b]heptylene) were determined by membrane osmometry in toluene solution and those of the polystyrenes were determined by vapour-pressure osmometry in chloroform. 

GPC utilizes nonpolar organic mobile phases, such as THF, trichlorobenzene, toluene, and chloroform, to analyze for organic polymers such as polystyrene. GFC utilizes mobile phases that are water-based solutions and is used to analyze for naturally occurring polymers, such as proteins and nucleic acids. 

These polystyrene-based catalysts are effective for the cyanide displacements of 1-bromooctane and 1-chlorooctane, and also for the generation of dichlorocarbene from chloroform and aqueous sodium hydroxide, giving quantitative yields of (2,2-dichlorocyclopropyl)benzene from styrene. The catalysts may be recovered simply by filtering the reaction mixture. Unfunctionalized polystyrene does not catalyse these reactions. As well as improving product purification and catalyst recovery, this approach also avoids... 

The average molecular mass of synthesized polymers can be measured by SEC. This system has been called gel-permeation liquid chromatography, using porous polystyrene gel as the stationary phase material. Polymers are usually dissolved in THF or chloroform for separation by SEC. The molecular density... 

Gel permeation chromatographic measurements were performed oj a Waters Associates HPLC with i-Styragel columns (10, 10, 10, and 500ANG) in chloroform with a polystyrene calibration. 

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