Phase behavior and characterization of the poly(methyl methacrylate-co-octafluoropentyl methacrylate) [P(MMA-co-OFPMA)] by supercritical dispersion polymerization

Abstract

Various industries have been moving away from the use of organic solvents because of environmental regulations on safety hazards. To reduce the consumption of organic solvent to the minimum, a number of studies have been carried out using supercritical carbon dioxide (scCO2) as reaction medium to synthesize a variety of polymers in a heterogeneous reaction system. In this study, poly(methyl methacrylate-co-2,2,3,3,4,4,5,5-octafluoropentyl methacrylate) [P(MMA-co-OFPMA)] as a fluoric copolymer was prepared using supercritical dispersion polymerization in scCO2. The characterization for the prepared P(MMA-co-OFPMA) was investigated using the particle size and shape, the molecular weight (Mw), and thermal analysis. In addition, Pressure isotherms for phase behavior of binary and ternary systems between P(MMA-co-OFPMA) and association liquid fluid as well as the influence of quality of association solvents, weight average molecular weight (Mw), and cosolvents were measured.The experimental data of high pressure phase behavior for the P(MMA-co-OFPMA) in supercritical CHF3, CH2F2 and CHClF2 are presented for binary and ternary mixtures at temperatures ranging from 334K to 454K and pressures up to 194MPa. Changes of the pressure–temperature (p–T) slope of cloud–point curves for the P(MMA-co-OFPMA) [25:1]+CH2F2+methyl methacrylate (MMA) (or CHClF2) systems were measured and compared, along with cosolvents MMA (or CHClF2) mass fraction of 0.0∼30.0wt%. The phase behavior data for the P(MMA-co-OFPMA)+CH2F2+0.0∼95.0wt% CHClF2 systems are reported as a change in the p–T curve from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region as the CHClF2 mass fraction increases. The cloud–point curves for the P(MMA-co-OFPMA)+CHF3 and +CHClF2 mixtures were measured for a LCST region accordingly as the AIBN (1.0, 2.0, 3.0 and 4.0wt%) and mole ratio (MMA:OFPMA=20:1, 22:1, 25:1 and 30:1) increases.