Structure and volumetric properties of linear and triarm star polyethylenes from atomistic Monte Carlo simulation using new internal rearrangement moves
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abstract
A number of elementary Monte Carlo moves are introduced for branched chain molecules. More specifically, branch point flip brings about a displacement in space of a branch point and its neighboring atoms in the molecule without change in the connectivity. Furthermore, branch point slithering allows for branch point displacement along the backbone; in this case, the size of the branches involved is changed. Finally, the flip move is extended to a dimer and is further generalized to an n-mer segment. The new Monte Carlo moves are used together with previously developed moves for the study of structure and volumetric properties of melts composed of symmetric triarm star polyethylenes of different arm lengths in a united atom representation. It is shown that the new moves result in very efficient relaxation of the macromolecules and, in particular, of their branch points. Comparisons are made against simulation results and experimental data for linear and branched polyethylene. The agreement between experimental data and Monte Carlo simulation for the melt density is good in all cases.
