Fractionation of Poly(ethylene glycol) between liquid phases

Abstract

We studied the fractionation of poly(ethylene oxide) (PEO) in isobutyric acid and water at different temperatures below the critical point. To do so, different molecular weight PEO with different end groups have been used. All the solutions were prepared at the critical composition of the binary liquids. During the fractionation, the polymer distributes itself in the lower and upper phases as a function of molecular weight. The results of the higher molecular weight polymer confirmed previous studies done by Shresth. The current studies show that the molecular weight and the end group of the polymer seem to have no effect on the fractionation. The fractionation of the lower molecular weight PEO with OCH3 termination is most powerful when compare to the higher molecular weight with OH end group. Two non-linear equations were then used to fit the number fractions molecular weight distributions in order to determine the type of distribution. The relative mass of polymer in each phase is then calculated. Most of the polymer migrates to the upper phase leaving almost little in the lower phase. The ratio of the mass fraction in the upper phase to that in the lower phase is roughly four.