Vm. Siderko et al., Phase transitions in the aqueous and aqueous-organic solutions of N-isopropylacrylamide copolymers with vinyl heptadecyl ketone, POLYM SCI B, 42(9-10), 2000, pp. 239-241
The copolymers of N-isopropylacrylamide with vinyl heptadecyl ketone with a
varying ratio of the comonomer units were synthesized by free-radical poly
merization, and the phase transitions of these copolymers in aqueous and aq
ueous-organic media were studied. The lower critical solution temperature i
n aqueous solution is decreased as the content of vinyl heptadecyl ketone u
nits in macromolecules is increased. The presence of inorganic salts in the
aqueous medium leads to a reduction in the temperature of phase transition
, while in the case of quaternary pyridinium salts, the effect is reversed.
The phase transition temperature of copolymer solutions shows an extremum
dependence on the composition of the mixed solvent water-tetrahydrofurane (
dioxane, acetone), and its minimum value is observed at the volume fraction
of organic component equal to 0.3, 0.45, and 0.5 for tetrahydrofurane, dio
xane, and acetone, respectively.