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Review

Volume Transition and Phase Coexistence in Polyelectrolyte Gels Interacting with Amphiphiles and Proteins

Department of Pharmacy, Uppsala University, Box 532, SE-75123 Uppsala, Sweden
Received: 10 July 2020 / Revised: 4 August 2020 / Accepted: 6 August 2020 / Published: 13 August 2020
(This article belongs to the Special Issue New Era in the Volume Phase Transition of Gels)
Polyelectrolyte gels have the capacity to absorb large amounts of multivalent species of opposite charge from aqueous solutions of low ionic strength, and release them at elevated ionic strengths. The reversibility offers the possibility to switch between “storage” and “release” modes, useful in applications such as drug delivery. The review focuses on systems where so-called volume phase transitions (VPT) of the gel network take place upon the absorption and release of proteins and self-assembling amphiphiles. We discuss the background in terms of thermodynamic driving forces behind complex formation in oppositely charged mixtures, the role played by cross-links in covalent gels, and general aspects of phase coexistence in networks in relation to Gibbs’ phase rule. We also briefly discuss a gel model frequently used in papers covered by the review. After that, we review papers dealing with collapse and swelling transitions of gels in contact with solution reservoirs of macroions and surfactants. Here we describe recent progress in our understanding of the conditions required for VPT, competing mechanisms, and hysteresis effects. We then review papers addressing equilibrium aspects of core–shell phase coexistence in gels in equilibrium. Here we first discuss early observations of phase separated gels and results showing how the phases affect each other. Then follows a review of recent theoretical and experimental studies providing evidence of thermodynamically stable core–shell phase separated states, and detailed analyses of the conditions under which they exist. Finally, we describe the results from investigations of mechanisms and kinetics of the collapse/swelling transitions induced by the loading/release of proteins, surfactants, and amphiphilic drug molecules. View Full-Text
Keywords: polyelectrolyte; gel; microgel; network; surfactant; protein; drug; macroion; volume phase transition; phase coexistence; phase separation; hysteresis; swelling; collapse; theory; modeling polyelectrolyte; gel; microgel; network; surfactant; protein; drug; macroion; volume phase transition; phase coexistence; phase separation; hysteresis; swelling; collapse; theory; modeling
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MDPI and ACS Style

Hansson, P. Volume Transition and Phase Coexistence in Polyelectrolyte Gels Interacting with Amphiphiles and Proteins. Gels 2020, 6, 24. https://doi.org/10.3390/gels6030024

AMA Style

Hansson P. Volume Transition and Phase Coexistence in Polyelectrolyte Gels Interacting with Amphiphiles and Proteins. Gels. 2020; 6(3):24. https://doi.org/10.3390/gels6030024

Chicago/Turabian Style

Hansson, Per. 2020. "Volume Transition and Phase Coexistence in Polyelectrolyte Gels Interacting with Amphiphiles and Proteins" Gels 6, no. 3: 24. https://doi.org/10.3390/gels6030024

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