Search for the origin of discrepancies in osmotic measurements of the PNIPAM - water system

Enikő Manek, Etelka Tombácz, Erik Geissler, K. László

Research output: Contribution to journalArticle

3 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)39-50
Number of pages12
JournalPeriodica Polytechnica: Chemical Engineering
Volume61
Issue number1
DOIs
Publication statusPublished - 2017

Fingerprint

Hydrogels
Water
Gels
Ions
Ionic strength
Homopolymerization
Titration
Swelling
Thermodynamic properties
poly-N-isopropylacrylamide

Keywords

  • DSC
  • Ionic strength
  • Osmotic pressure
  • PH
  • PNIPAM

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

Search for the origin of discrepancies in osmotic measurements of the PNIPAM - water system. / Manek, Enikő; Tombácz, Etelka; Geissler, Erik; László, K.

In: Periodica Polytechnica: Chemical Engineering, Vol. 61, No. 1, 2017, p. 39-50.

Research output: Contribution to journalArticle

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