Tuneable extraction systems based on hyperbranched polymers

By the use of hyperbranched polymers as tunable solvent in extraction processes, the solubility of the polymers is important. If the solubility limit is gone below, there is a crystallization of the polymer hindering the extraction process. On the other hand, the liquid-liquid equilibrium has an impact on the crystallization. For this reason, the superposition of liquid-liquid and solid-liquid equilibria of binary solutions of hyperbranched polymers was investigated theoretically. As model systems hyperbranched polyesters Boltorn W3000 dissolved in methanol, ethanol and propan-1-ol were considered, which form a demixing system. For the calculation of the phase equilibria the lattice cluster theory (LCT) was combined with the extended chemical association lattice model (ECALM). The developed thermodynamic model is able to simultaneously model the liquid-liquid equilibrium and the solid-liquid equilibrium with the same model parameters, whereas the model results are in good agreement with experimental data taken from the literature.