Structural properties of hyperbranched polymers in the melt under shear via nonequilibrium molecular dynamics simulation.

Hyperbranched polymer melts have been simulated using a coarse-grained model and nonequilibrium molecular dynamics (NEMD) techniques. In order to determine the shear-induced changes in the structural properties of hyperbranched polymers, various parameters were calculated at different strain rates. The radii of gyration which characterize the size of the polymer were evaluated. The tensor of gyration was analyzed and results indicate that hyperbranched polymer molecules have a prolate ellipsoid shape under shear. As hyperbranched polymers have compact, highly branched architecture and layers of beads have increasing densities which might lead to an unusual distribution of mass, the distribution of beads was also studied. The distribution of terminal beads was investigated to understand the spatial arrangement of these groups which is very important for hyperbranched polymer applications, especially in drug delivery.