Effect of Terminal Hydrophobic Groups on the Behavior of Linear Poly-2-Isopropyl-2-Oxazoline in Aqueous Solution

Light scattering, turbidimetry, and viscosimetry have been used to study aqueous solutions of poly-2-isopropyl-2-oxazolines differing in the structure of their hydrophobic terminal groups. The phase separation temperature was determined. A complex temperature dependence was found for the viscosity of these solutions featuring an inflection point near the phase separation temperature. The addition of polyacrylic acid to a solution of poly-2-isopropyl-2-oxazoline has only a weak effect on the phase transition temperature but has a considerable effect on the viscosity of the system.