Trans‐1,4‐stereospecific copolymerization of ethylene and isoprene catalyzed by MgCl₂‐supported Ziegler–Natta catalyst

Abstract

Copolymerization of ethylene and isoprene (Ip) catalyzed by TiCl 4 /MgCl 2 -Al(i-C 4 H 9 ) 3 catalyst was systematically studied. Homopolymer of ethylene and Ip were synthesized under the same conditions for making comparisons. Proton nuclear magnetic resonance was employed to characterize chain structure of the copolymer. Influences of Ip concentration, molar ratio of cocatalyst to Ti and reaction temperature on the copolymerization activity and copolymer chain structure were investigated. The copolymerization activity was evidently lowered by increasing Ip concentration, and the Ip content in copolymer was rather low under reaction conditions leading to higher activity. Insertions of Ip in polymer chain showed rather high regioselectivity for 1,4-connections (>85%) and medium to high stereoselectivity for trans-1,4-isomer (>70%) under typical conditions, but the regio and stereoselectivities tended to decrease with decrease in Ip concentration and increase in Al/Ti ratio. Melting temperature of the copolymer decreased with increase of Ip content, indicating incorporation of Ip units in most of the copolymer chains. This work has proved feasibility of introducing small amount of Ip units with high trans-1,4-stereoselectivity into ethylene/isoprene copolymer chains by catalyzed copolymerization with MgCl 2supported Ziegler-Natta catalysts. The copolymer is expected to be a promising candidate of easily degradable film or packaging materials.Since the 1990s, copolymerization of olefins with conjugated dienes like butadiene and isoprene has been studied by different researchers. Ethylene-butadiene and ethylene-isoprene copolymerizations catalyzed by anza-zirconocenes provided copolymers with 1,4-inserted diene units, but cyclic structures formed by intramolecular cyclization were also identified. [21][22][23] Additional supporting information may be found in the online version of this article.S. Song and X. Liu contributed equally to this article.

Ethylene‐Butadiene Copolymerization and Ethylene‐1‐Hexene‐Butadiene Terpolymerization with a MgCl2‐Supported Ziegler‐Natta Catalyst: Polymer Structure and Active Centers

“…It means that the copolymerization reaction has high regio/stereoselectivity for trans‐ 1,4 insertion of butadiene. This is quite similar with the situation of ethylene‐butadiene copolymerization with SiO 2 ‐supported half‐titanocene catalyst [7] and ethylene‐buradiene or ethylene‐isoprene copolymerizations with MgCl 2 ‐supported Z−N catalyst [12,13,26] …”

“…reported ethylene‐propylene‐isoprene terpolymerization catalyzed with half‐scandocene complexes activated by borate, and found that the products contained both 1,4‐ and 3,4‐ connected isoprene units in comparable amount [25] . In our previous work, ethylene‐isoprene copolymerization with MgCl 2 ‐supported Ziegler‐Natta catalysts was studied, and the produced copolymer was found to contain predominantly trans ‐1,4‐isoprene units, though the incorporation rate of isoprene was relatively low [26,27] …”

Comparative Analysis of Ethylene/Diene Copolymerization and Ethylene/Propylene/Diene Terpolymerization Using Ansa-Zirconocene Catalyst with Alkylaluminum/Borate Activator: The Effect of Conjugated and Nonconjugated Dienes on Catalytic Behavior and Polymer Microstructure

“…The vanadium- (VOCl 3 , VCl 4 , VO(OR) 3 and V(acac) 3 ) and titanium-based heterogeneous Zeigler‒Natta catalysts have been used in the copolymerization of ethylene with conjugated diene. Unfortunately, the copolymerization activity was significantly reduced due to the stronger coordination efficiency of the conjugated diene than ethylene [ 17 , 18 , 19 , 20 , 21 ]. It is difficult to use vanadium (V) since discoloration, ageing, and toxicity are induced by the polymer’s residual V content over 5–10 ppm.…”

Rapid kinetic evaluation of homogeneous single-site metallocene catalysts and cyclic diene: how do the catalytic activity, molecular weight, and diene incorporation rate of olefins affect each other?

“…PEs resins are used in product packaging, thin lms, pipelines, tubes, and household appliances, among so many other things. [5][6][7][8][9] Cyclic norbornene (NB) and its derivatives (ENB and VNB) have a ring strain in their structure and are easily polymerized via cationic, radical, and vinyl-type addition. [10][11][12] Cyclic di-olens prepared via vinyl-type addition show superior properties such as excellent optical transparency, chemical resistance, moisture absorption, and low birefringence.…”