Phase separation of two- and three-component solution for the poly(pentyl acrylate-co-methyl methacrylate) + compressed solvents and copolymer preparation by supercritical dispersion polymerization

Abstract

Copolymers of poly(pentyl acrylate-co-methyl methacrylate) [P(PA-co-MMA)] were manufactured by using carbon dioxide with dispersion polymerization. The thermophysical characteristics of P(PA-co-MMA) were researched with three kinds ratios (1:20, 1:25, and 1:30) of PA vs. MMA and AIBN concentrations of (1.0, 2.0, and 4.0) wt%. Experimental product source at pressures of p≤206MPa and temperature of T≤434K was investigated for two- and three-components solution of P(PA-co-MMA) under compressed CO2, CHClF2, CHF3 and CH2F2. Experiments are carried out to get phase separation measurement for the two-component solution of P(PA-co-MMA) [1:25 mole ratio, AIBN of (1.0, 2.0 and 4.0wt%]+compressed fluorine solvents (CHF3, CHClF2and CH2F2) solutions at a pressure of p<168MPa and temperature of (333≤T≤434) K. It is revealed that the CH2F2+P(PA-co-MMA) solution is seen as the upper critical solution temperature(UCST) type with negative curves, while the CHClF2+P(PA-co-MMA) and CHF3+P(PA-co-MMA) solutions appear in the lower critical solution temperature(LCST) region with positive curves. Phase equilibria curves for P(PA-co-MMA) [mole ratio 1:20 (Mw=198,000gmol−1), 1:25 (Mw=249,000gmol−1) and 1:30 (Mw=258,000gmol−1), AIBN of 1.0wt%]+compressed (CHF3, CHClF2 and CH2F2) solutions depict a negative curves for CH2F2+P(PA-co-MMA) and a positive curves for the CHF3+P(PA-co-MMA) and CHClF2+P(PA-co-MMA) solutions at T≤434K and at p≤168MPa. The effect of MMA co-solvent contents of (0.0–42.5) wt% [or (0.0–30.4) wt% PA, (0.0–97.1) wt% CHClF2] on phase separation for the CH2F2+P(PA-co-MMA) (1:20 and 1:25 mole ratio, AIBN of 1.0wt%) solutions is found in shifts of the (p, T) diagram from (LCST to UCST) slope. Phase equilibria data for P(PA-co-MMA)+(19.9–97.1) wt% CHF3 [or (35.9–97.1) wt% CHClF2] solution in compressed CO2 is depicted from a negative slopes to a positive slopes, which means that the interaction between copolymer and (co)solvents is more favorable than the interaction between (co)solvents and (co)solvents.