Abstract
The series of ethylene-norbornene (E-NB) copolymers was obtained using different vanadium homogeneous and supported ionic liquid (SIL) catalyst systems. The 13C and 1H NMR (carbon and proton nuclear magnetic resonance spectroscopy) together with differential scanning calorimetry (DSC) were applied to determine the composition of copolymers such as comonomer incorporation (CNB), monomer dispersity (MD), monomer reactivity ratio (re), sequence length of ethylene (le) and tetrad microblock distributions. The relation between the type of catalyst, reaction conditions and on the other hand, the copolymer microstructure, chain termination reaction analyzed by the type of unsaturation are discussed. In addition, the thermal properties of E-NB copolymers such as the melting and crystallization behavior, like also the heterogeneity of composition described by successive the self-nucleation and annealing (SSA) and the dispersity index (DI) were determined.
Highlights
Cyclic olefins copolymers (COCs) have gained attention owing to their unique properties, which make them attractive as high-tech engineering plastics
The norbornene incorporation is higher for the catalyst with bidentate C4 than tridentate C5 pyridinium ligands
The immobilization of metallocene complex results in disappearance of the trisubstituted vinylene groups in the copolymer and appearance of vinylene groups. These results clearly indicate that the ionic liquid influences both the suppression of isomerization reaction and the β-H transfer to the metal center of the last monomer and favors the comonomer 2,1-type insertion
Summary
Cyclic olefins copolymers (COCs) have gained attention owing to their unique properties, which make them attractive as high-tech engineering plastics. Poly(ethylene-co-norbornene) materials show many interesting properties like a moisture barrier (4–5 times higher than low density polyethylene (LDPE)) [3], good solvent resistance, facile processability, high thermal stability, transparency and stiffness [6]. These copolymers are a promising class of thermoplastics, ranging from highly crystalline solids to elastomers, whose properties depend on the norbornene content and copolymer microstructure [7,8,9,10]. It is important to determine the microstructure of copolymers in order to understand their different polymer properties, so that to improve significantly their commercial use [6,11]
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