Thermal Reshaping Dynamics of Gold Nanorods: Influence of Size, Shape, and Local Environment

The thermal reshaping of gold nanorods in a polymer matrix is an important phenomenon for many potential applications. However, a fundamental understanding of the various mechanisms that govern the nanorod reshaping dynamics is still lacking. Here, we provide evidence for a phenomenological model of the gold nanorod shape transformation based on the measurements and detailed analysis of the time-resolved thermal reshaping for a variety of gold nanorods having different geometries (aspect ratio, volume, diameter) in a cross-linked epoxy matrix at application relevant temperatures (120–220 °C). Our analysis suggests that (a) the nanorod reshaping dynamics consist of two temporal regimes that are governed by different phenomena and (b) the ultimate amount of reshaping at a given temperature depends strongly on the initial particle geometry and the mechanical stiffness of its surroundings. At short times, the shape transformation is dominated by a curvature-induced surface diffusion process, in which the acti...