Behavior of thermoresponsive ionogenic poly(2-isopropyl-2-oxazoline) stars and their mixture in aqueous solutions

Abstract

Star-shaped eight-arm poly(2-isopropyl-2-oxazoline)s with basic and acidic groups were synthesized using a “grafting from” approach. Molar masses were 13,700 and 14,900 g mol⁻¹ for polybase and polyacid, respectively. The aqueous solutions of synthesized polymers and their mixture were investigated by the light scattering and turbidimetry methods within wide range of temperatures and pH values. It was shown that the studied polymers separately do not exhibit pH-sensitivity due to the low content of ionogenic groups. For the solutions of mixture, one phase transition was detected, the onset temperature T₁ of which lies between the phase separation temperatures for polymers. The value of T₁ for mixture decreases with increasing acidity of the medium.

Keywords:

• Poly(2-alkyl-2-oxazolines)
• thermoresponsive polymers
• pH-responsive polymers
• star-shaped macromolecules
• phase separation

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Russian Science Foundation under Grant no 17-73-20318.