Effect of the Structure of Arms and Way of Their Attachment to Calix[4]arene on Self-Assembly Processes in Aqueous Solutions of Thermoresponsive Star-Shaped Poly(2-alkyl-2-oxazolines) and Poly(2-alkyl-2-oxazines)

Abstract

The aqueous solutions of star-shaped four-arm poly(2-alkyl-2-oxazolines) and poly(2-alkyl-2-oxazines), in which the upper rim-functionalized calix[4]arene acts as a branching center, are studied by static and dynamic light scattering and turbidimetry. It is shown that at low temperatures in aqueous solutions of these polymer stars aggregates are formed as a result of interaction of hydrophobic calix[4]arene cores and formation of hydrogen bonds between dehydrated monomer units of arms. The process of aggregation dominates upon heating of the solutions. Varying the mode of arm attachment to a core causes a change in its configuration. The values of the phase transition temperature decrease when comparing polymers with the lower rim-functionalized core with polymers in which arms are attached to the upper rim of calix[4]arene.