Effect of Molecular Weight on Reactive Molecular Dynamics Simulations: Guiding the Theoretical Study for Macromolecules at an Atomic Level

Some constructions of the molecular model for reactive molecular dynamics (RMD) simulations have neglected the effect of molecular weight on the RMD results. A computational methodology for generating structural models of amorphous ultrahigh molecular weight polyethylene (UHMWPE) with different degrees of polymerization was thus proposed. The methodology was then used in RMD simulations of three types of molecular models for UHMWPE with 20, 40, and 80 vinyl monomers. The accuracy of the model has been discussed by comparing the RMD results with experimental data previously available in the literature. Results have confirmed that the atomic model with larger molecular weight allows (i) exact calculations of the diffusion coefficient and (ii) accurate prediction of the cross-linked reaction. The RMD simulations provide the basic data for understanding and further studying the chemical reaction of other interesting macromolecules.