Adsorption of poly(methacrylic acid) onto differently charged silica nanoparticles and its consequences on particles clustering
ROBIN ; LORTHIOIR ; ERMAN ; PEREZ ; FALL ; OVARLEZ ; AMIEL ; LE COEUR
Type de document
NOTE INTERNE OU DE TRAVAIL
Langue
anglais
Auteur
ROBIN ; LORTHIOIR ; ERMAN ; PEREZ ; FALL ; OVARLEZ ; AMIEL ; LE COEUR
Résumé / Abstract
This work aims at gaining a comprehensive picture of the interactions between three differently functionalized silica nanoparticles and a polyacid - PMAA namely - in aqueous media. Native silica nanoparticles and silica nanoparticles functionalized with amine or quaternary amine groups are either negatively or positively charged with various charge densities whereas PMAA chains display an increasing negative charge density as the pH is increased from 3 to 9. Adsorption isotherms were obtained by Total Organic Carbon (TOC) and evidenced stronger adsorptions at pH = 3, for which PMAA chains are neutral and display an hypercoil conformation. In this last case, the more hydrophobic the silica surface is, the higher the adsorption. At higher pH values, electrostatic interactions are the main driving force of PMAA/surface interactions. Small-angle X-ray scattering experiments were performed on PMAA/silica dispersions under the condition of saturation adsorption in order to correlate the extent of particle dispersion with polymer/surface interactions. The stronger the polymer/surface interactions, the more compact aggregates are formed.
