Nonconjugated diene homopolymerization and copolymerization with ethylene catalyzed by α‐diimine Ni(II) complex/Et₂AlCl

Abstract

Four nonconjugated diene comonomers 1,9‐decadiene (19DD), 6‐ethylundeca‐1,10‐diene (EUD), 1,5‐cyclooctadiene (COD) and cinene (1‐methyl‐4‐(prop‐1‐en‐2‐yl) cyclohex‐1‐ene) (CE) were used in copolymerization with ethylene catalyzed by α‐diimine Ni(II) complex ([2,6‐(iPr)2C6H3N = C(CH3)−(CH3)C = N2,6‐(iPr)2C6H3)]NiBr2 (1)) activated by Et2AlCl. These dienes showed quite distinct copolymerization behaviors. Ethylene‐19DD copolymerization formed highly branched polyethylene with cyclic units and pendent vinyls, and a large part of crosslinked polymer when the 19DD concentration was relatively high. Using EUD as comonomer lead to evidently reduced gel formation and increased content of pendent vinyl. COD can be incorporated in the copolymer with evidently lower catalyst efficiency than the ethylene homopolymerization, and CE behaves like an inert compound as it was not incorporated in the copolymer. Homopolymerization of 19DD with the same catalyst produced polymer containing both cyclic units and pendent vinyls. The cyclic units were formed by cyclopolymerization of the inserted 19DD after several steps of chain walking. Crosslinking through the pendent vinyl took place when the initial 19DD concentration was relatively high, forming large amount of gel in the product. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1900–1909

Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene

“…Their increased contents in the copolymer resulted in lower T g values (Figure 12a and Tables 1 and 2) due to the absence of sterically rigid cyclic and cross-linked units (Figure 11, type II and III). The similar changes in T g caused by incorporation of sterically encumbered monomer units, like cyclic rings, was reported in the literature related to ethylene copolymerization with unconjugated dienes [50].…”

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

“…To overcome the drawbacks of PE materials, it is necessary to conduct modifications on their molecular chains. Introducing carbon–carbon double bonds by copolymerization has been regarded as an effective way to modify the polymer backbone Alternatively, introduction of carbon–carbon double bonds in PE chains could allow for indirect functionalization through further chemical modification like thiol‐ene click reaction . Because incorporation of double bonds in PE backbone will form allylic hydrogens that can initiate photooxidative degradation more efficiently than the methylene hydrogens in conventional PE, PE films containing unsaturated carbon–carbon double bonds could show significantly accelerated photooxidative degradation.…”

α,ω-Diene Generation from Ethylene and Butadiene by Copolymer Upcycling

“…α,ω-Dienes, analogues of α-olefins, have been much less explored, potentially due to challenges in preparation. In addition to similar applications as α-olefins, they also serve as comonomers to prepare branched polyolefins and precursors for difunctionalized monomers for polymerization. − However, reported preparations of α,ω-dienes typically require multiple steps from cyclic olefinic precursors and are only applicable for several specific dienes. ,, For example, dimerization and trimerization of butadiene afford a mixture of 1,5-cyclooctadiene and 1,5,7-cyclododecatriene. Partial hydrogenation of 1,5-cyclooctadiene followed by ethenolysis affords the desired 1,9-decadiene .…”