Isoprene Polymerization: Catalytic Performance of Iminopyridine Vanadium(III) Chloride versus Vanadium(III) Chloride.

Mengmeng Zhao,Liang Wang,Chuyang Jing,Guangqian Zhu,Qaiser Mahmood,Qinggang Wang,Xianhui Zhang

doi:10.3390/polym11071122

Abstract

A series of vanadium complexes bearing iminopyridine bidentate ligands with various electronic and steric properties: V1 [CH2Ph], V2 [CMe2CH2CMe3], V3 [Ph] and V4 [2,6-iPr2Ph] were prepared and characterized by IR spectroscopy and microanalytical analysis. The catalytic capacity of all the complexes has been investigated for isoprene polymerization and was controlled by tuning the ligand structure with different N-alkyl and N-aryl groups. Activated by methylaluminoxane (MAO), the aryl-substituted complex V3 [Ph] exhibited high cis-1,4 selectivity (75%), and the resultant polymers had high molecular weights (Mn = 6.6 × 104) and narrow molecular weight distributions (PDI = 2.3). This catalyst showed high activity up to 734.4 kg polymer (mol V)−1 h−1 with excellent thermostability even stable at 70 °C. Compared to the traditional VCl3/MAO catalytic system, iminopyridine-supported V(III) catalysts displayed higher catalytic activities and changed the selectivity of monomer enchainment from trans-1,4 to cis-1,4.

Highlights

Polydienes, a class of multipurpose elastomers which play a vital role in modern society, have attracted considerable attention of both industrial and academic communities
We reported the synthesis of a series of iminopyridine vanadium(III) complexes and employed as catalysts for isoprene polymerization
The general method of new vanadium complexes used in this study shownisinshown generalsynthetic synthetic method of new vanadium complexes used in thisisstudy

Summary

Introduction

Polydienes, a class of multipurpose elastomers which play a vital role in modern society, have attracted considerable attention of both industrial and academic communities. Advantages typical of both rubber and plastic materials make them superior over vulcanized rubber, these polymeric materials are widely employed as commodity material in tires, medical materials, sporting goods etc. Polyisoprenes are identified as important synthetic elastomer, due to their diversified microstructures [1,2, 3,4, cis-1,4 and trans-1,4 stereoregularities in polymer] and thereby, a strong influence on the properties of the resulting polymer.

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