Polymerization dynamics in nonequilibrium environments

A polymer growth Hamiltonian with an accompanying novel lattice has been constructed to model reaction dynamics of polydisperse polymer systems whose kinetics are affected by an environment that is altered over time by the polymerization process itself. The polymerization process is simulated using MC dynamics with bond breaking/formation moves analogous to that of a correlated percolation model. Lattice events occur on the time scale of reactivity rather than the much shorter time scales of either monomer motion or conformational dynamics. The equilibrium behavior of the system has been well mapped out and is complex enough to model a variety of real polymer systems such as solid state polymerization, living polymers and thermosetting polymers. Detailed equilibrium structural information such as molecular weight distributions and extent of cross-polymerization have been obtained. Pseudodynamic information such as the time-dependence in the polymer weight distribution and more detailed quantities may also be obtained with respect to Monte Carlo time scales. The model has been studied in two and three dimensions yielding similar equilibrium and dynamic behavior. Remarkably, the model does not exhibit the same reduced dimensional effects seen in other models. The faster two dimensional calculations may consequently be used to model polymer behavior in three dimensions, but this has the disadvantage of preventing the study of two dimensional surface effects on the polymerization process.; Stochastic molecular dynamics beyond lattices have been studied through a mechanical system whose projection is a generalization of the generalized Langevin equation with non-stationary friction. This iGLE (irreversible generalized Langevin equation) can be used to model polymerization dynamics in non-equilibrium environments. A combination of the lattice MC and iGLE methods can potentially be used to obtain real-time dynamics for cross-linked polymer systems such as thermosets.