Polymer cosolvent system: Poly(vinyl-2-pyridine)/toluene/ethyl acetate

Phase Behavior of Polymers in Supercritical Fluid Solvents

“…However, once the acrylate groups are titrated with butanol, further increase in butanol concentration favors cosolvent−cosolvent hydrogen bonding that decreases the region of miscibility. Many authors report findings for other polymer−solvent−cosolvent systems that are consistent with this behavior. ,,− , More modest changes in solubility behavior are observed if a polar cosolvent is used that does not hydrogen bond. For example, when 4-heptanone is added to PMMA−chlorobutane mixtures, the UCST decreases monotonically with heptanone concentration over only a 10 °C range …”

“…It is worthwhile to mention briefly some of the results from studies done with polar homopolymers in liquid cosolvent mixtures, ,,− since there are direct corollaries to high-pressure polymer−SCF solvent phase behavior. For example, Wolf and Blaum 63 show that small amounts of 2-butanol reduce the UCST of the poly(methyl methacrylate) (PMMA)−chlorobutane system by as much as 70 °C as the 2-butanol hydrogen bonds to the basic acrylate group in the backbone of the polymer.…”

“…Decoupling the effect of a cosolvent from that of hydrostatic pressure is sometimes complicated since increasing the system pressure also reduces the free volume difference between the solvent and the polymer and increases the probability of interaction between polymer, solvent, and cosolvent segments in solution. 64 It is worthwhile to mention briefly some of the results from studies done with polar homopolymers in liquid cosolvent mixtures, 19,62,[65][66][67][68][69][70][71] since there are direct corollaries to high-pressure polymer-SCF solvent phase behavior. For example, Wolf and Blaum 63 show that small amounts of 2-butanol reduce the UCST of the poly(methyl methacrylate) (PMMA)-chlorobutane system by as much as 70 °C as the 2-butanol hydrogen bonds to the basic acrylate group in the backbone of the polymer.…”

“…Many authors report findings for other polymer-solvent-cosolvent systems that are consistent with this behavior. 19,62,[65][66][67][68][69][70]72 More modest changes in solubility behavior are observed if a polar cosolvent is used that does not hydrogen bond. For example, when 4-heptanone is added to PMMAchlorobutane mixtures, the UCST decreases monotonically with heptanone concentration over only a 10 °C range.…”