Dynamics of water and sodium in gels under salt-induced phase transition

Matan Mussel, Ella Wilczynski, Uzi Eliav, Jonathan Gottesman, Michal Wilk, Uri Nevo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Synthetic and biological gels undergo a sharp volume phase transition when subjected to a variety of environmental changes. Water and ion dynamics within swollen and compact phases are critical for understanding fundamental concepts in cellular (specifically neuronal) biophysics, for models of bound, free, or ordered water in complex environments; and for practical applications such as the design of gels for drug release, biomimetics, sensors, or actuators. In this work, we find, for the first time, basic physical parameters that shed light on the interaction of gels with water and electrolytes, across a volume phase transition. Water within a gel can be separated into bound and free populations with high exchange rate. We show that free water dynamics in compact gels are the same as those in pure water. Bound water was found to comprise a single layer around the polymers in both phases, with a correlation time three orders of magnitude higher than that of free water. Most importantly, salt-induced phase transition was found to be different from a standard coil-globule transition (e.g., temperature-induced), with no rejection of bound water as the gel compacts.

Original languageEnglish
Pages (from-to)1620-1628
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume53
Issue number22
DOIs
StatePublished - 15 Nov 2015

Funding

FundersFunder number
Israel Science Foundation1156/12

    Keywords

    • NMR
    • diffusion
    • hydrogels
    • molecular dynamics

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