Ortega Daniela E, Cortés-Arriagada Diego
Centro Integrativo de Biología y Química Aplicada (CIBQA), Universidad Bernardo O'Higgins, General Gana 1702, Santiago 8370854, Chile.
Instituto Universitario de Investigación y Desarrollo Tecnológico (IDT), Universidad Tecnológica Metropolitana, Ignacio Valdivieso 2409, San Joaquín, Santiago 8940577, Chile.
Polymers (Basel). 2025 May 6;17(9):1268. doi: 10.3390/polym17091268.
Understanding the catalytic behavior of heterogeneous systems for the copolymerization of ethylene with polar monomers is essential for developing advanced functional polyolefins. In this study, we conducted a quantum chemical investigation of the SiO-supported Ni-allyl-α-imine ketone catalyst (Ni-OH@SiO) to uncover the factors governing monomer insertion, selectivity, and reactivity. Using DFT calculations and energy decomposition analysis (ALMO-EDA), we evaluated the coordination and insertion of six industrially relevant polar monomers, comparing their behavior to ethylene homopolymerization. Our results show that special polar monomers (SPMs) with aliphatic spacers, such as vinyltrimethoxysilane (vTMS) and 5-hexenyl acetate (AMA), exhibit favorable insertion profiles due to enhanced electrostatic and orbital interactions with minimal steric hindrance. In contrast, fundamental polar monomers (FPMs), including methyl acrylate (MA) and vinyl chloride (vCl), show higher activation barriers and increased Pauli repulsion due to strong electron-withdrawing effects and conjugation with the vinyl group. AMA displayed the lowest activation barrier (7.4 kcal/mol) and highest insertion thermodynamic stability (-17.6 kcal/mol). These findings provide molecular-level insight into insertion mechanisms and comonomer selectivity in Ni-allyl catalysts supported on silica, extending experimental understanding. This work establishes key structure-reactivity relationships and offers design principles for developing efficient Ni-based heterogeneous catalysts for polar monomer copolymerization.
了解非均相体系中乙烯与极性单体共聚的催化行为对于开发先进的功能聚烯烃至关重要。在本研究中，我们对SiO负载的Ni-烯丙基-α-亚胺酮催化剂（Ni-OH@SiO）进行了量子化学研究，以揭示控制单体插入、选择性和反应性的因素。使用密度泛函理论（DFT）计算和能量分解分析（ALMO-EDA），我们评估了六种工业相关极性单体的配位和插入情况，并将它们的行为与乙烯均聚进行了比较。我们的结果表明，具有脂肪族间隔基的特殊极性单体（SPMs），如乙烯基三甲氧基硅烷（vTMS）和乙酸5-己烯酯（AMA），由于静电和轨道相互作用增强且空间位阻最小，表现出良好的插入特征。相比之下，基本极性单体（FPMs），包括丙烯酸甲酯（MA）和氯乙烯（vCl），由于强吸电子效应和与乙烯基的共轭作用，显示出更高的活化能垒和增加的泡利排斥力。AMA表现出最低的活化能垒（7.4 kcal/mol）和最高的插入热力学稳定性（-17.6 kcal/mol）。这些发现为二氧化硅负载的Ni-烯丙基催化剂中的插入机制和共聚单体选择性提供了分子水平的见解，扩展了实验认识。这项工作建立了关键的结构-反应性关系，并为开发用于极性单体共聚的高效镍基非均相催化剂提供了设计原则。
