How does star polymer architecture affect dynamical heterogeneity?

The formation of an amorphous solid by polymers is one of the most important features for polymer applications. While glass formation of linear chain polymers has been widely explored, comparatively little is known about glass formation of star polymers. We study the dynamical heterogeneity and cooperative nature of star polymer melts via molecular dynamics simulations. In particular, we quantify how the number of arms and the length of those arms affect the collective string-like motion of monomers. We find that, while the star geometry can significantly affect the size and time scale of collective motions, the relationship between the size scale of the collective motions and the overall relaxation time follows the same Adam-Gibbs like relationship previously found to describe simple linear polymers.