Surface segregation of nanoparticles driven by supercritical carbon dioxide

Surface segregation (i.e., preferential segregation of one component to the surface in multicomponent systems) is common to all material classes and is typically driven by a reduction in surface energy which compensates for the entropy loss and/or energy gain associated with the demixing of the components. However, the conventional surface segregation for polymeric systems requires high temperatures, typically close to 200°C, and long annealing time, in order to ensure enough polymer mobility. Here we show a low-temperature method to preferentially migrate organoclay nanoparticles to the polymer surface using supercritical carbon dioxide.