Equilibrium Swelling of Thermo-Responsive Gels in Mixtures of Solvents

Aleksey D. Drozdov, Jesper de Claville Christiansen

Research output: Contribution to journalArticlepeer-review


Thermo-responsive (TR) gels of the LCST (lower critical solution temperature) type swell in water at temperatures below their volume phase transition temperature (Formula presented.) and collapse above the critical temperature. When water is partially replaced with an organic liquid, these materials demonstrate three different types of equilibrium solvent uptake diagrams at temperatures below, above, in the close vicinity of (Formula presented.). A model is developed for equilibrium swelling of TR gels in binary mixtures of solvents. It takes into account three types of phase transitions in TR gels driven by (i) aggregation of hydrophobic side groups into clusters from which solvent molecules are expelled, (ii) replacement of water with cosolvent molecules in cage-like structures surrounding these groups, and (iii) replacement of water with cosolvent as the main element of hydration shells around backbone chains. The model involves a relatively small number of material constants that are found by matching observations on covalently cross-linked poly(N-isopropylacrylamide) macroscopic gels and microgels. Good agreement is demonstrated between the experimental data and results of numerical analysis. Classification is provided of the phase transition points on equilibrium swelling diagrams.

Original languageEnglish
Pages (from-to)681-700
Number of pages20
JournalChemistry (Switzerland)
Issue number3
StatePublished - 1 Sep 2022
Externally publishedYes


  • mixture of solvents
  • organohydrogel
  • swelling
  • thermo-responsive gel
  • volume phase transition

ASJC Scopus subject areas

  • Electrochemistry
  • Inorganic Chemistry
  • Organic Chemistry
  • Chemistry (miscellaneous)


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