Model-guided targeted synthesis and structural regulation of polyethylene via α-diimine nickel/MAO-catalyzed ethylene homopolymerization in a microflow system

Revealed Al/Ni and catalyst concentration effects on polymer structure. • Clarified how propagation, chain walking, and transfer determine conversion, branching degree and molecular weight. • Developed a mechanism-inspired model for polyethylene property prediction. • Enabled inverse design for target-oriented polyethylene synthesis. Ethylene homopolymerization catalyzed by an α-diimine nickel/MAO system was investigated in toluene using a microflow platform. The effects of catalyst concentration and Al/Ni ratio on polymerization behavior and polymer structure were systematically examined. Increasing catalyst concentration enhanced the overall polymerization capability but also intensified chain-transfer effects, while the Al/Ni ratio exhibited an optimal window governed by the balance between catalyst activation and activity suppression at excessive MAO levels. Based on the chain-walking mechanism, polymer structure formation was interpreted as a dynamic competition among chain propagation, chain walking, and chain transfer, which mainly determined conversion, branching degree, and molecular weight. A mechanism-inspired apparent model was established by combining variable transformations, a third-order polynomial response surface, and Ridge regularization, enabling simultaneous prediction of key polymer properties. Furthermore, an inverse design model was developed for identifying feasible reaction conditions toward target-oriented polyethylene synthesis. Download: Download high-res image (140KB) Download: Download full-size image