Molecular dynamics simulation of collinear polymer nanoparticle collisions: Reaction and scattering

Collinear collisions of polyethylene nanoparticles are studied, with a part icular emphasis on the transition between sticking and reactive scattering trajectories. The former are characterized by collisions where the two poly mer particles form a particle dimer, the latter by collisions resulting in the gross change of particle structure, such as particle fragmentation or t ransfer of polymer chains from one particle to another. It is observed that in the collinear case there are no scattering trajectories where the parti cles undergo nearly elastic collisions and rebound with small energy change . This property is attributed to the fact that during the collision process the particles undergo reorganization, and the energy involved is difficult to recover. The result is that at all but extremely high velocities, parti cles undergo rapid and irreversible energy transfer from the relative trans lational coordinate into other internal coordinates, resulting in dimerizat ion of the polymer particles.