title: Thermally sensitive reversible microgels formed by poly(N-Isopropylacrylamide) charged chains: a Hofmeister effect study.
abstract: In this study, we present a new method to obtain anionic and cationic stable colloidal nanogels from PNIPAM charged chains. The stability of the particles formed by inter-chain aggregation stems from the charged chemical groups attached at the sides of PNIPAM polymer chains. The particle formation is fully reversible-that is, it is possible to change from stable polymer solutions to stable colloidal dispersions and vice versa simply by varying temperature. In addition, we also demonstrate that the polymer LCST (lower critical solution temperature), the final particle size and the electrokinetic behavior of the particles formed are highly dependent on the electrolyte nature and salt concentration. These latter results are related to Hofmeister effects. The analysis of these results provides more insights about the origin of this ionic specificity, confirming that the interaction of ions with interfaces is dominated by the chaotropic/kosmotropic character of the ions and the hydrophobic/hydrophilic character of the surface in solution.
authors.affiliation: EC2M, UMR Gulliver CNRS-ESPCI 7083 - 10 Rue Vauquelin, F-75231 Paris Cedex 05, France.
authors.forename: Teresa
authors.initials: T
authors.lastname: López-León
authors.affiliation: Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva S/N, 18071 Granada, Spain.
authors.forename: Juan L
authors.initials: JL
authors.lastname: Ortega-Vinuesa
authors.affiliation: Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva S/N, 18071 Granada, Spain. Electronic address: dbastos@ugr.es.
authors.forename: Delfi
authors.initials: D
authors.lastname: Bastos-González
authors.affiliation: University of Lyon, F-69622 Lyon, France; University of Lyon-1, Villeurbanne, CNRS, (UMR 5007), LAGEP-CPE-308G, 43 bd. du 11 Nov. 1918, F-69622 Villeurbanne, France.
authors.forename: Abdelhamid
authors.initials: A
authors.lastname: Elaissari
keywords: Electrokinetic behavior; Hofmeister effects; Microgels