Direct mixing of cellulose triacetate (CTA) in acetone at room temperature produces only an opaque swollen gel at all concentrations. However, cycling the mixture between room temperature and -78 +/- 3degreesC results in a stable solution at room temperature, if the concentration is less than 6% (w/w). This process has been called "cold-solutioning." Such a process also produces a clear solution at concentrations between 6% (w/w) and 10%, (w/w); however, in time, the solution separates slowly into at least two phases, a clear liquid and an opaque gel phase. At concentrations above 10% (w/w) and below 20% (w/w), the system exhibits two phases. A completely opaque swollen gel forms at concentrations of 20% (w/w) and above. The above-described cold-solutioning phenomena are shown to be the coupled kinetic and thermodynamic consequences of (1) the large thermal stresses that would result from thawing a swollen mixture of CTA and acetone, arising from the large differences in their thermal expansion coefficients; and (2) the "bimodal" composition of the cellulose derivative. (C) 2003 Wiley Periodicals, Inc.