Application of Reaction Time Accelerating Molecular Dynamic to Modeling of Metallocene-Catalyzed Ethylene/1-butene Copolymerization

Abstract

This paper presents an efficient method to integrate chemical reactions into molecular dynamics. The methodology requires no more than the knowledge of the empirical intermolecular potentials for the species at play as well as the elementary reaction path among them. We have applied the method to evaluate the reaction rate of copolymerization of ethylene and 1-butene using C₅(CH₃)₄-Si-(CH₃)₂-N-C₅(CH₃)₃-C-(CH₃)₃-Ti-Cl₂)/methylaluminoxane catalyst, and have successfully demonstrated the propagation dynamics under the same conditions as in the experiment. The reaction rate was estimated from the calculated amount of the polymerized monomers by introducing principles of transition state theory. The calculated reaction rates are comparable with experiment, which illustrates the validity of the method. The simplicity of the RTAMD scheme enables the simulation of large scale systems involving large numbers of simultaneous chemical reactions and the evaluation of the reaction rate.