Colloid and Polymer Science

, Volume 296, Issue 9, pp 1431–1441 | Cite as

Ionic strength and ion-specific effects on the cloud point and the gel swelling of thermo-sensitive polymers in water

  • Risa Tanaka
  • Shuto Watanabe
  • Yuki Kagamihara
  • Mitsuru SatohEmail author
Original Contribution


In the present study, we have confirmed that the LCST behavior of thermosensitive polymers such as poly(vinyl methyl ether) (PVME) may be notably influenced by addition of small amount of neutral salts. In fact, the PVME gel swelled with increasing NaCl concentration in the immersing solution up to 10−3 M and then deswelled. Further, ionic effects on the hydrophobic interaction of PVME proved to be significantly dependent on the ionic species; for example, in the presence of 10−4 M halide ions (Cl, Br, and I), the cloud point of PVME solution significantly increased in the order of Cl < I < Br. This is different from the typical Hofmeister series, Cl < Br < I, which is observed in much higher salt concentration region. All these ion effects have been interpreted in terms of the dual adsorption model for OH and H+ on hydrophobic interface.


Poly(vinyl methyl ether) Poly(N-isopropyl acrylamide-co-methacrylic acid) OH adsorption Hofmeister series Hydrophobic interaction 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

396_2018_4363_MOESM1_ESM.pdf (413 kb)
ESM 1 (PDF 412 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Risa Tanaka
    • 1
  • Shuto Watanabe
    • 1
  • Yuki Kagamihara
    • 1
  • Mitsuru Satoh
    • 1
    Email author
  1. 1.Department of Chemical Science and Engineering, School of Materials and Chemical TechnologyTokyo Institute of TechnologyTokyoJapan

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