Figure 7.

Molecular dynamics simulations of the formation of rubber. (left) The two molecular units, butadiene (left) (C brown sphere, H white sphere), and acrylonitrile (right) (N blue sphere), which are allowed to polymerize to yield a rubber chain. (right) A full optimization of a system of 5 chains, containing 65% of butadiene molecules of 50 units each, modified with hydroxyl groups (OH-) (O red sphere). The cubic system obeys periodic boundary conditions (PBC) and has a cell size of about 30 Å (adapted from [65]).