In this paper, the experimental research concerning the impact of the hydrophilic-hydrophobic transition of a polymer exhibiting the Upper Critical Solution Temperature (UCST) onto the crystallization process of inorganic salt is presented. A hypothesis was postulated that under favorable process conditions the sudden change of macromolecules properties and the resulting appearance of insoluble particles will induce the nucleation process of the salt. Since the transition point parameters may be precisely designed, the described mechanism would eliminate the stochastic nature of the crystallization process. Although performed experiments proved that the postulated process mechanism was incorrect, the presence of macromolecules had a significant impact on the crystallization course. The stochastic nature of the process was not eliminated; nevertheless, it seems that a specific point of nucleation was created which was independent of the cloud point temperature (TCP) of the polymer. Moreover, the surface morphology of crystals was changed.
Keywords: KCl; nucleation; phase transition; poly(acrylic acid) (PAA); upper critical solution temperature (UCST).