Liquid–liquid phase equilibria of hyperbranched polymers—Experimental study and modeling

The cloud-point curve of the system hyperbranched polyester Boltorn H40 + water is visually measured and the new experimental data are presented. The stability of the aqueous solutions is studied under measuring conditions by size exclusion chromatography (SEC) and FT-IR, proving that the aqueous polyester solution degraded after a longer time of stay at 400 K. The liquid–liquid equilibrium of the systems Boltorn H40 + water and Boltorn H20 + water is calculated using the lattice-cluster theory (LCT) combined with the extended chemical association lattice model (ECALM). Generally, in ECALM there are cross associates (uniform in composition) and self associates of one of the components. The association effects have proven to influence strongly the liquid–liquid equilibrium. Considering the architecture of the polymer molecules and the association effects in this way, both systems are modeled in good accordance with the experimental data.