Dispersion, Phase Separation, and Self-Assembly of Polymer-Grafted Nanorod Composites

Abstract

A systematic understanding of the miscibility of grafted nanorods in polymer melt is required in order to synthesize materials and make devices with controllable properties. While there have been a number of studies on the effect of graft length and graft density on the miscibility of grafted nanorods, the effect of graft arrangement and nanorod geometry remains to be explored. We use integral equation theory to study the dispersion, macrophase separation, and self-assembly of sparsely grafted nanorods in polymer melt. This phase behavior is studied as a function of nanorod diameter, aspect ratio, and density as well as the length and arrangement of the polymer grafts. The phase behavior of these systems is a result of a competition between matrix-induced depletion attraction between nanorods and the steric stabilization provided by grafts. Because of steric shielding of the grafts, nanorod miscibility usually increases with graft length, and trans-grafted rods are more soluble than cis-grafted rods. Depl...