A compositional window of kinetic stability for amphiphilic polymers and colloidal nanorods

Abstract

Amphiphilic polymers are often used to disperse nanoparticles in aqueous solution. Polymer adsorption theory predicts that there exists a narrow compositional range of hydrophobic groups on the polymer chain that allows for kinetic stabilization. Too few groups limit polymer adsorption, while too many allow aggregation of polymer-coated nanoparticles for lack of entropic repulsion. We experimentally validate and mathematically describe the existence of this compositional range, and the resulting stability "window" for the first time using a phenoxy-dextran polymer to disperse single-walled carbon nanotubes. The results should provide a theoretical basis for the design of nanoparticle dispersants. © 2011 American Chemical Society.