We report a simulation study for bottle-brush polymers grafted on a rigid backbone. Using a standard coarse-grained bead-spring model extensive molecular dynamics simulations for such macromolecules under good solvent conditions are performed. We consider a broad range of parameters and present numerical results for the monomer density profile, density of the untethered ends of the grafted flexible backbones and the correlation function describing the range that neighboring grafted bottle-brushes are affected by the presence of the others due to the excluded-volume interactions. The end beads of the flexible backbones of the grafted bottle-brushes do not access the region close to the rigid backbone due to the presence of the side chains of the grafted bottle-brush polymers, which stretch the chains further in the radial directions. Although a number of different correlation lengths exist as a result of the complex structure of these macromolecules, their properties can be tuned with high accuracy in good solvents. Moreover, qualitative differences with 'typical' bottle-brushes are discussed. Our results provide a first approach to characterizing such complex macromolecules with a standard bead-spring model.

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Abstract. We report the results of three dimensional molecular dynamic simulations on the angle of repose of a sandpile formed by pouring mono-sized cohesionless spherical grains into a granular Hele-Shaw cell. In particular, we are interested to investigate the effects of those variables which may impact significantly on pattern formation of granular mixtures in Hele-Shaw cells. The results indicate that the frictional forces influence remarkably the formation of pile on the grain level. Furthermore, We see that increasing grain insertion rate decreases slightly the angle of repose. We also find that in accordance with experimental results, the cell thickness is another significant factor and the angle of repose decays exponentially by increasing the cell thickness. It is shown that this effect can be interpreted as a cross-over from two to three dimensions. In fact, using grains with different sizes shows that the behavior of the angle of repose when both size and cell thickness are varied is controlled by a scaled function of the ratio of these two variables. † corresponding author