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Polymerization Mechanism of α-Linear Olefin
Wen-guo Xing,Chang-qiao Zhang*,Ping Yu,Cheng-bu Liu,Yun-he Wei
Author NameAffiliationE-mail
Wen-guo Xing School of Chemistry and Chemical Engineering, Shandong University, Ji'nan 250061, China  
Chang-qiao Zhang* School of Chemistry and Chemical Engineering, Shandong University, Ji'nan 250061, China zhangchqiao@sdu.edu.cn 
Ping Yu School of Chemistry and Chemical Engineering, Shandong University, Ji'nan 250061, China  
Cheng-bu Liu School of Chemistry and Chemical Engineering, Shandong University, Ji'nan 250061, China  
Yun-he Wei School of Chemistry and Chemical Engineering, Shandong University, Ji'nan 250061, China  
Abstract:
The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetry restrictions for reactants, products, the possible transition states, and intermediates was calculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as flloes: (i) Coordination compounds were formed on the optimum configuration of TiCl3/AlEt2Cl.(ii) The transition states were formed. The energy di?erence between transition states and the coordination compounds was 40.687 kJ/mol. (iii) Double bond opened and Ti-C(4) bond fractured, and the polymerization was completed. The calculation results also showed that the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization.
Key words:  Density functional theory, Polymerization mechanism, α-Linear olefin, Drag reduction agent, Ziegler-Natta catalyst
FundProject:
Polymerization Mechanism of α-Linear Olefin
邢文国,张长桥*,于萍,刘成卜,魏云鹤
摘要:
利用密度泛函理论在B3LYP方法6-31G水平上对α-直链烯烃在TiCl3/AlEt2Cl催化体系的链增长规律进行了相应的计算.对反应物、产物以及各种可能的中间体和过渡态进行了全参数优化,在同一理论水平上对势能面上的全部驻点进行了振动频率分析,并从过渡态分别向反应物和产物方向进行了内禀反应坐标计算.计算结果表明,在TiCl3/AlEt2Cl催化剂优化的构型上首先形成配位化合物,进而形成过渡态,过渡态与配位化合物的能量差为40.687 kJ/mol,最后是双键打开和Ti-C(4)断裂,从而完成整个聚合反应历程.计算结果也初步表明随着α-直链烯烃碳原子数的增加,链增长机理未发生本质变化.由聚合反应活化能与α-直链烯烃碳原子数的关系可以看出,碳原子数为6~10时反应活化能较低,是聚合反应合成减阻剂的最佳选择.
关键词:  密度泛函理论,聚合机理,α-直链烯烃
DOI:10.1088/1674-0068/23/01/39-44
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