Experimental measurement of solubility curves for poly(methyl methacrylate-co-pentafluorophenyl methacrylate) in supercritical solvents

Abstract

The seven poly(methyl methacrylate-co-pentafluorophenyl methacrylate) [P(MMA-co-PnFPMA)] copolymers were prepared by dispersion polymerization under supercritical carbon dioxide. The physicochemical characterisation for the P(MMA-co-PnFPMA) was investigated with varied mole ratios of MMA vs PnFPMA (30:1, 25:1 and 20:1), AIBN amounts (1.0, 2.0 and 4.0wt%) and the weight average molar mass (Mw).Experimental values at temperatures from (333 to 453)K and pressures up to 229MPa are reported for binary and ternary mixtures of P(MMA-co-PnFPMA) in supercritical CO2, CH2F2, CHF3 and CHClF2. Phase behaviour of binary systems for the P(MMA-co-PnFPMA) (mole ratio=25:1, 1.0wt%, 2.0wt%, and 4wt% AIBN)+supercritical fluoric solvents (CH2F2, CHF3 and CHClF2) mixtures at temperature range from (333 to 434)K and pressure up to 168MPa are measured for the upper critical solution temperature (UCST) type behaviour with negative slope for the {P(MMA-co-PnFPMA)+CH2F2} as well as for the lower critical solution temperature (LCST) type curve with positive slope for the {P(MMA-co-PnFPMA)+CHF3} and {P(MMA-co-PnFPMA)+CHClF2} mixtures. Cloud-point curves for the {P(MMA-co-PnFPMA) [mole ratio=30:1 (Mw=157,000), 25:1 (Mw=149,000), and 20:1 (Mw=142,000): 1.0wt% AIBN; 30:1 (Mw=109,000), 25:1 (Mw=94,000), and 20:1 (Mw=88,000): 2.0wt% AIBN]+supercritical (CH2F2, CHF3 and CHClF2)} mixtures show a negative slope for the P(MMA-co-PnFPMA)+CH2F2, and a positive slope for the {P(MMA-co-PnFPMA)+CHF3} and {P(MMA-co-PnFPMA)+CHClF2} mixtures at temperatures to 435K and pressures up to 150MPa. Also, the impact of MMA on phase behaviour for the P(MMA-co-PnFPMA) (mole ratio=25:1; AIBN: 1.0wt% and 2.0wt%)+CH2F2 mixtures are measured in changes of the (pressure+temperature) (p, T) slope from UCST behaviour to LCST behaviour, and with MMA co-solvent concentrations of (0.0 to 39.0)wt%. Phase behaviour for the {P(MMA-co-PnFPMA)+(14.7 to 96.4)wt% CHF3 [or (27.9 to 97.1)wt% CHClF2]} mixture in supercritical CO2 show favourably better (fluorocopolymer+solvents) interaction than (solvents+solvents) interaction, changing from a negative slope to a positive slope.