R. Horst and B. Gerharz

"Phase behavior of the ternary system water / hydroxyethyl cellulose /
nonionic surfactant"

*Colloid and Polymer Science* **1996**, *274*, 439-445.

**Abstract:** The phase behavior of ternary aqueous solutions of two samples
of hydroxyethyl cellulose (HEC) and oligoethylene glycol mono(n-alkyl) ethers
C(x)E(y) (x: 11; y: 28, 40) at 25 degrees C has been studied above the CMC of
C(x)E(y). The influence of molar mass of HEC and the number of ethylene glycol
units on the phase diagram has been investigated. Both binary systems water/HEC
and water/C(x)E(y) are completely miscible. The ternary mixture of water/polymer/nonionic
surfactant is homogeneous if the weight fraction of water is larger than 0.93,
or else it can separate segregatively, i.e., HEC is enriched in one phase, the
surfactant in the other. The theoretical description is based on an equation
for the Gibbs energy of mixing which takes polar conformations into account.
The phase diagrams are calculated by means of a new method which does not require
the derivatives of the Gibbs energy of mixing.

preprint number: 168a