Phase Behavior of the Binary and Ternary Mixtures of Biodegradable Poly(ε-caprolactone) in Supercritical Fluids

Abstract

Experimental cloud-point data for poly(ε-caprolactone) in supercritical CO2, CHClF2, dimethyl ether(DME), 1-butene, and propylene at high pressure were measured at temperatures from 40 to 230 °C and pressures up to 2 830 bar. Poly(ε-caprolactone) was dissolved well in DME and CHClF2 below 500 bar and in CO2, 1-butene, and propylene in the range of 1 600−2 830 bar. A comparison of phase behavior was made between poly(ε-caprolactone) (Mw = 170 000) and poly(caprolactone) (Mw = 14 000) in supercritical CO2 and DME. The solubility of the poly(ε-caprolactone)−CO2−DME (0.0, 4.5, 14.5, 40.4, and 100 wt %) system with cosolvent concentration is measured in the range of temperature of 55−230 °C and at pressures as high as 2 830 bar. The cloud point for the ternary poly(ε-caprolactone)−CO2−CHClF2 mixture with 4.9, 14.3, and 44.5 wt % CHClF2 in cosolvent is measured at the temperature range of 40−230 °C and at the pressure range of 43−2 830 bar. The cloud point for the poly(ε-caprolactone)−propylene−DME system with DME concentrations of 9.5, 21.2, and 42.4 wt % is measured in the temperature range of 55−200 °C and at pressures as high as 1 825 bar. This system shows the change of the pressure−temperature relationship between the phase-behavior curves in the upper critical solution temperature (UCST) region of the negative slope, according to DME concentrations of 9.5, 21.2, and 42.4 wt %. The poly(ε-caprolactone)−propylene−CHClF2 (8.4, 22.9, and 41.9 wt %) system shows the phase-behavior curves from the UCST region to the lower critical solution temperature (LCST) region as the CHClF2 concentration increases. The experimental cloud-point data for the poly(ε-caprolactone)−1-butene−DME mixture with each of 0.0, 9.5, 31.1, 52.4, 80.6, and 100 wt % DME concentrations is measured in the temperature range 40−200 °C and at pressures up to 1825 bar.