GAS-CHROMATOGRAPHIC AND STATIC MEASUREMENTS OF SOLUTE ACTIVITY FOR A POLYMERIC LIQUID-CRYSTALLINE PHASE

Inverse gas chromatographic methods allow measurements of solvent activity over polymeric liquid-crystalline phases. Aqueous solutions of hydroxypropyl cellulose form an ordered fluid phase at high polymer concentrations and also exhibit a lower critical solution temperature. Several gas chromatographic and static techniques were used to measure the activity of water in concentrated hydroxypropylcellulose solutions. The results are compared with osmotic pressure measurements in the literature. Within experimental precision, the activity appears to vary smoothly with concentration. It is suggested that in this system the polymer-solvent interaction parameter may have the same value at each end of the concentration range, but the entropy of mixing changes from that predicted by Flory's theory for rodlike mixing at high polymer concentrations to that for Flory-Huggins mixing in dilute solution. © 1979, American Chemical Society. All rights reserved.