Monte Carlo Simulation of Long-Chain Branched Polyolefins Made with Dual Catalysts; A Classification of Chain Structures in Topological Branching Families

The production of polyolefins by use of two single-site catalysts, where one of the catalysts forms linear chains only (linear catalyst) and the other makes linear and long-chain branched chains (LCB catalyst), is an attractive route to control the molecular architecture of branched polyolefins. For modeling purposes, these chains can be conveniently divided into families containing different numbers of long-chain branches per chain, However, when the number of long-chain branches per chain is higher than three, there is more than one possible chain topology for each family; that is, highly branched families have several family members. In this paper, we developed a Monte Carlo model to describe how the fraction and molecular weight distribution of these family members vary as a function of the ratio of linear to LCB catalyst used during polymerization,