A Monte Carlo-based feeding policy for tailoring microstructure of copolymer chains: Reconsidering the conventional metallocene catalyzed polymerization of α-olefins

• Exact kinetic modeling of metallocene synthesis of ethylene/α-olefin copolymers.
• Determination of comonomer content drift due to comonomer consumption.
• Development of simple comonomer replenishing strategies to avoid composition drift.
• Determination of differences between conventional with controlled comonomer feeding.
• Simulation of thermal properties of tailored ethylene/α-olefin copolymer chains.

A standard Monte Carlo-based program with innovative data storage structure was developed and put into practice to tailor ethylene/1-hexene copolymers through semibatch single site metallocene catalyzed copolymerization. The distribution of copolymer composition, ethylene sequence length, longest ethylene sequence length, as well as the number-average degree of polymerization, and sequential placement of 1-hexene comonomer segments along copolymer chains were monitored and evaluated applying a computerized feeding to metallocene catalyzed ethylene/1-hexene copolymerization. In particular, bivariate copolymer composition–chain length (CC–CL) distribution was compared for two feeding recipes with uncontrolled and well-controlled comonomer insertion. The advantages of controlled feeding in comparison to uncontrolled feeding were discussed in view of aforementioned architectural features. To obtain macromolecules with tailored comonomer distributions, special feeding strategies were developed by training and examining the developed model to capture crystallization analysis fractionation (CRYSTAF) of ethylene/1-hexene chains, as a unique signature of tailored copolymers with rather narrow bivariate CC–CL distribution. The simulation results appropriately highlight the critical importance of computerized feeding with respect to uncontrolled feeding.

A kinetic Monte Carlo simulation is utilized to screen microstructure development in conventional coordination copolymerization of ethylene and 1-hexene. A comonomer feeding strategy is devised to achieve chains with predetermined ethylene sequence lengths.Figure optionsDownload as PowerPoint slide