Osmotic de-swelling of ionic microgel particles

Autor:	Brian Vincent, Alberto Fernandez-Nieves, A. Fernández-Barbero, F. J. de las Nieves
Rok vydání:	2003
Předmět:	Chemistry General Physics and Astronomy Ionic bonding Thermodynamics Charge density Osmosis chemistry.chemical_compound Colloid symbols.namesake Dextran Polymer chemistry medicine symbols Osmotic pressure Physical and Theoretical Chemistry Swelling medicine.symptom Debye length
Zdroj:	The Journal of Chemical Physics. 119:10383-10388
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.1618734
Popis:	In this work, we study experimentally the effect of an external osmotic pressure πext on the swelling of ionic mesoscopic gels in the weak screening limit, where the Debye screening length is larger than the mesh size of the gel. Variations in the osmotic pressure were induced by adding dextran to the solution. The results show that ionic microgels do not respond to πext below a given value of the normal stress; above this value the system de-swells with increasing osmotic pressure. The start of de-swelling is set by the gel charge density. The Flory thermodynamic theory for ionic gels captures the essential characteristics of the de-swelling behavior; in particular, it predicts with fairly good accuracy the value of πext at which de-swelling begins. Finally, due to the colloidal character of the gels, we observe that the system flocculates by a depletion interaction mechanism at high dextran concentrations.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::da4db6e05c4fe0b5d1f300f9a9ba3c8b https://doi.org/10.1063/1.1618734 Zobrazit plný text záznamu