Thermoresponsive phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) solutions in propyl acetate/n-alkane mixed solvents

Thermoresponsive phase behavior of poly(2-chloroethyl vinyl ether-alt-maleic anhydride) (P(CVE-MA)) in mixed solvent of propyl acetate (PrAc) and n-alkane has been investigated. At a proper solvent composition of PrAc/n-octane, the polymer solution was transparent at lower temperature, and became turbid with heating, which suggest that this polymer solution exhibits lower critical solution temperature (LCST) type phase behavior. Controllability of the cloud point of the polymer solution was studied by light scattering technique. At the fixed polymer concentration of 1 mass%, the cloud point value changed from 76 °C to 31 °C with increasing the n-octane content from 6 to 16 mass% in the mixed solvent, with excellent linear relationship. The cloud point curve plotted against polymer concentration shifted to higher temperature with decreasing molecular weight of P(CVE-MA). The cloud point curve also shifted to higher temperature when the chain length of the added n-alkane became longer, and this result was explained by n-alkaneʹs polarity and molecular size.