Pressure Changes Across a Membrane Formed by Coacervation of Oppositely Charged Polymer-Surfactant Systems

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Behnam Keshavarzi - , Chair of Transport Processes at Interfaces, Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Georg Reising - , TUD Dresden University of Technology (Author)
  • Mohsen Mahmoudvand - , University of Calgary (Author)
  • Kaloian Koynov - , Max Planck Society (Author)
  • Hans-Jurgen Butt - , Max Planck Society (Author)
  • Aliyar Javadi - , Helmholtz Association of German Research Centres, TUD Dresden University of Technology (Author)
  • Karin Schwarzenberger - , Chair of Transport Processes at Interfaces, Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Sascha Heitkam - , Chair of Transport Processes at Interfaces, Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Michelle Dolgos - , University of Calgary (Author)
  • Apostolos Kantzas - , University of Calgary (Author)
  • Kerstin Eckert - , Chair of Transport Processes at Interfaces, Helmholtz-Zentrum Dresden-Rossendorf (Author)

Abstract

We investigate the mass transfer and membrane growth processes during capsule formation by the interaction of the biopolymer xanthan gum with C(n)TAB surfactants. When a drop of xanthan gum polymer solution is added to the surfactant solution, a membrane is formed by coacervation. It encapsulates the polymer drop in the surfactant solution. The underlying mechanisms and dynamic processes during capsule formation are not yet understood in detail. Therefore, we characterized the polymer-surfactant complex formation during coacervation by measuring the surface tension and surface elasticity at the solution-air interface for different surfactant chain lengths and concentrations. The adsorption behavior of the mixed polymer-surfactant system at the solution-air interface supports the understanding of observed trends during the capsule formation. We further measured the change in capsule pressure over time and simultaneously imaged the membrane growth via confocal microscopy. The cross-linking and shrinkage during the membrane formation by coacervation leads to an increasing tensile stress in the elastic membrane, resulting in a rapid pressure rise. Afterward, the pressure gradually decreases and the capsule shrinks as water diffuses out. This is not only due to the initial capsule overpressure but also due to osmosis caused by the higher ionic strength of the surfactant solution outside the capsule compared to the polymer solution inside the capsule. The influence of polymer concentration and surfactant type and concentration on the pressure changes and the membrane structure are studied in this work, providing detailed insights into the dynamic membrane formation process by coacervation. This knowledge can be used to produce capsules with tailored membrane properties and to develop a suitable encapsulation protocol in technological applications. The obtained insights into the mass transfer of water across the capsule membrane are important for future usage in separation techniques and the food industry and allow us to better predict the capsule time stability.

Details

Original languageEnglish
Pages (from-to)9934-9944
Number of pages11
JournalLangmuir
Volume40
Issue number19
Publication statusPublished - 1 May 2024
Peer-reviewedYes

External IDs

PubMed 38690991
Scopus 85192464122
ORCID /0000-0002-2493-7629/work/168207376

Keywords

Keywords

  • Polyelectrolyte/surfactant mixtures, Air/water interface, Mechanical-properties, Adsorption behavior, Neutron reflection, Dodecyl-sulfate, Phase-behavior, Xanthan, Capsules, Tension