Effect of electrolyte-induced polymer swelling on macromolecule functionalized core–shell nanoparticle interaction potential: Calculation of colloidal stability ratio

Swelling/deswelling properties of core–shell nanoparticles play an essential role in determining the stability of colloidal suspensions. Desolvation of polymers chains induced by variation of pH, temperature and/or ionic strength increases their lyophobicity favoring aggregation. Knowledge of the hydrophilic character of the surface layer against external stimuli enables the prediction of the aggregation state of the nanoparticles and the tuning their colloidal stability. ive a theoretical model based on the DLVO assumptions elaborated by Vold and Vincent to study the stability of core–shell nanoparticles able to swell/deswell by varying the concentration of monovalent electrolyte, CS. We studied the instability ratio, W−1, and the interparticle potential, φT, CS as a function of concentration by varying attraction, repulsion, geometry, and swelling ratio, σ, of the nanoparticle. nd the strength of the colloidal interaction, β, is mainly affected by the repulsive energy, while nanoparticle aggregation is favored by an increase in the salt sensitivity to dehydration, kS. Our findings allow to directly relate both φT and W−1 to the swelling/deswelling ability of the polymer layer and to predict the colloidal stability of a variety of core–shell nanomaterials including hydrogel modified, stimulus-responsive, and protein functionalized nanoparticles.