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Macromolecules, 2014, 47 (4), pp 1462–1469.
Bastian Ebeling , Steffen Eggers , Michael Hendrich, Annika Nitschke , Philipp Vana *
Institut für Physikalische Chemie, Georg-August-Universität, Tammannstr. 6, D-37077 Göttingen, Germany.
Abstract
It was demonstrated for several organic cononsolvents added to aqueous solutions of poly(N-isopropylacrylamide) that they lead to an increasing solubility of the polymer in the low-temperature/high-pressure region while reducing the solubility of the polymer and therefore its cloud temperature at atmospheric pressure. A complete inversion of the phase-separation behavior regarding both the effects of pressure and temperature was found by increasing the mole fraction of added ethanol over the whole cononsolvency range. As a special case, at a mole fraction of x = 0.23 the system cleared up independent of temperature at a constant pressure of about 1000 bar. The measurements were performed in an optical high-pressure cell up to pressures of 3000 bar and down to temperatures of −20 °C. The results are discussed in terms of solvent–solvent and solvent–polymer interactions.
Copyright © 2014 American Chemical Society.
