Search for the Origin of Discrepancies in Osmotic Measurements of the PNIPAM - Water System

Authors

  • Enikő Manek
    Affiliation

    Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Hungary

  • Etelka Tombácz
    Affiliation

    Department of Physical Chemistry and Materials Science, University of Szeged, Hungary

  • Erik Geissler
    Affiliation

    Laboratoire Interdisciplinaire de Physique, Université Grenoble Alpes and CNRS, France

  • Krisztina László
    Affiliation

    Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Hungary

https://doi.org/10.3311/PPch.10273

Abstract

Major, still unelucidated, inconsistencies exist in the literature among measurements of the thermodynamic properties of poly(N-isopropylacrylamide) (PNIPAM) solutions and gels. This paper looks for evidence of intrinsic ionic behaviour in cross-linked PNIPAM homopolymer hydrogels synthesized in water under standard conditions. Systematic measurements are made of the swelling and osmotic properties of lightly cross-linked PNIPAM hydrogels, as well as of their potentiometric titration and DSC response, over a wide range of pH and ionic strength conditions, in order to distinguish the effects of the latter two parameters on putative intrinsic ions. The intrinsic ion content of the gel is found to be vanishingly small, and consequently unlikely to be the source of the divergences among past measurements. By contrast, a major finding of this study is that comparison of the present results with the literature reveals that frustrated equilibrium can be a source of substantial discrepancies.

Keywords:

PNIPAM, osmotic pressure, DSC, ionic strength, pH

Published Online

2017-01-23

How to Cite

Manek, E., Tombácz, E., Geissler, E., László, K. “Search for the Origin of Discrepancies in Osmotic Measurements of the PNIPAM - Water System”, Periodica Polytechnica Chemical Engineering, 61(1), pp. 39–50, 2017. https://doi.org/10.3311/PPch.10273

Issue

Section

Articles