LAUSR

Abstract A series of thermoresponsive random copolymers based on 2- n -propyl-2-oxazoline ( n PrOx) and 2-ethyl-2-oxazoline, and gradient copolymers of 2- n -propyl-2-oxazoline with 2-methyl- or 2-isopropyl-2-oxazoline were synthesized by living cationic polymerization. In each copolymer series a similar ratio of comonomers was applied. The study focused on behavior of the obtained copolymers in aqueous solution. The effect of the copolymer composition and concentration on the cloud points and the aggregation was followed by the UV–Vis and dynamic light scattering measurements. The copolymers displayed complex aggregation behavior dependent on the polymer concentration and temperature. The atomic force microscopy was used to visualize the particles formed by the n PrOx copolymers. The phase transition for copolymers was reversible. The gradient copolymers exhibited noticeable hysteresis the value of which was dependent on affinity of comonomers to water and on copolymer composition.