The Osmotic Pressure of Concentrated Solutions of Polyethylene Glycol 6000, and its Variation with Temperature

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Abstract
The vapour pressures of aqueous solutions of polyethylene glycol 6000 have been measured (by equilibration with sucrose solutions) up to the saturation point at 25 °C (1.45 g g−1 water). The reduced-osmotic-pressure (π/c), when plotted versus concentration (c), rapidly and linearly increased up to a concentration of about 0.8 g g−1 (crossing the similar plot for sucrose). Above this concentration, the reduced-osmotic-pressure rose more slowly, but still more rapidly than sucrose. The maximum osmotic pressure achieved at saturation was nearly 18 MPa. Using the virial equation: π/c= RT/M + RTA2c, the calculated second virial coefficient (A2) for the linear part is 4.5 × 10−3 mol g−1, a value slightly greater than most literature values at 25 °C. Data are cited showing that A2 varies linearly from 5–6 × 10×3 at 0 °C, to zero at 80–90 °C