THERMAL STABILITY AND PHASE COMPOSITION OF STRATIFYING POLYMER SOLUTIONS IN SMALL-VOLUME DROPLETS

Within the framework of the thermodynamic approach the characteristic features of the phase equilibria and of thermal stability of liquid polymer solutions in small-volume systems are considered. Using as an example a stratifying solution of oligomer fractions of polybutadiene and polystyrene in coarsely disperse droplets of different volumes with core–shell confi guration, the regions of thermal stability of various heterogeneous states of the core– shell structure that differ by the compositions of core phases and of homogeneous state are obtained . It is shown that these regions of temperatures depend substantially on the droplet volume, with the compositions of the coexisting phases in different states of the core–shell structure being different. A decrease in the droplet volume is accompanied by a substantial change of the mutual solubilities of components, as well as by a decrease of the upper critical temperature of solubility and by the expansion of the temperature region, in which solutions of any composition up to the equimolar one are dynamically stable.
   
Author:  A. V. Shishulin and V. B. Fedoseev
Keywords:  disperse systems, dimensional effect, solutions of polymers, phase transformations, solution stratifi cation, metastable states
Page:  802