Dye Partition Methods

The amount of ionic end groups in high polymers has some bearing on the stability of "clean polymer colloids . In a recent publication Vanderhoff et al reported that the estimation of sulfate end groups by the dye partition method in polystyrene... 

From the foregoing discussion it is clear that the success of the dye partition method for the analysis of ionic end groups in polymers is controlled principally by the character of the organic solvent used in extraction and not by the polarity of the polymer. Solvents with some pennanent dipole moment capable of solvating... 

Ghosh and co-workers [42, 69] also described a dye partition method for the determination of hydroxyl end groups in PMMA samples prepared in aqueous... 

Saha and co-workers [70] and Palit [66, 67] developed a dye-partition method for the determination of halogen atoms in copolymers of styrene, methylmethacrylate, methylacrylate, or vinyl acetate with a chlorine-bearing monomer such as allyl chloride and tetrachloroethylene. Copolymers were quaternised with pyridine, then precipitated with petroleum ether or alcohol, and fnrther purified by repeated precipitation from their benzene solutions with a mixture of alcohol and petroleum ether as the non-solvent. The precipitated polymers were then washed with petroleum ether and dried in air. The test for quaternary halide groups in polymers was carried out with a reagent consisting of disulfine blue dissolved in 0.01 M hydrochloric acid and the colour evaluated spectrophotometrically at 630 nm. Saha and co-workers [70] and Palit [66, 67] found that there may be some imcertainty in the quantitative aspects of this method. 

A dye partition method has been decribed for the determination of low levels of nitrile groups in polystyrene [172]. 

Figure 4. Comparison of Different Methods for Determination of Sulfate Endgroups of Latex A-2 0 dye partition,...

Bonneau, R. Faure, J. Joussot-Dubien, J. Purification of thiazine dyes, azure A, azure B, and azure C, by a partition method. Talanta 1967, 14, 121-122. 

However, although several methods exist for estimating water solubility based on regression of water solubility against octanol/water partition coefficient, most have used data sets that do not include nonionic dyes. 

Paul and McSpadden studied the permeation of a red organic dye (Sudan III) in acetone through a silicone rubber membrane as shown in Figure 6.9. The partition coefficient of 0.148 has been independently determined for the dye in the membrane and in acetone by an extraction method. Calculate the diffusion coefficient and the solubility of the dye. Assume that the thickness and the diameter of the membrane are 0.15 cm and 8 mm, respectively. 

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