Modeling phase behavior of Poly(ɛ-caprolactone) solutions at high pressure

Abstract

Poly(ɛ-caprolactone) (PCL) is a biocompatible and biodegradable polymer and is widely used in controlled drug-delivery applications. For the production of polymeric microspheres loaded with pharmaceutical products, the supercritical fluid technology using carbon dioxide (CO2) is favored because of its non-toxic nature. In this work, the phase behavior of PCL in various supercritical solvents such as CO2, CHClF2, dimethyl ether (DME), 1-butene, and propylene is described by the PC-SAFT model. The effects of the molecular weight of PCL, the type of solvent, pressure, temperature, and the concentration of the cosolvent are investigated. The solubility of PCL in supercritical solvents is accurately described over a wide range of temperatures (from 293.15 to 503 K) and for pressures up to 300 MPa. CO2 shows the poorest solubility, while CHClF2 shows the highest solubility. The predicted cloud-point pressures show an increasing tendency with an increase of the molecular weight of the PCL. The addition of cosolvents, i.e., DME and CHClF2, to the PCL/CO2 solution increases of the dissolving power of the mixed solvent. The results predicted with the PC-SAFT equation of state are in good agreement with the experimental data.