Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

Abstract

Highly active para-t-Bu-containing 1,2-bis(imino)acenaphthene-Ni(ii) catalysts are disclosed which afford hyper-branched PEs with Mw's up to 3.1 × 106 g mol−1; high tensile strength, excellent shape fixity as well as high elongation at break are a feature.

Alkylaluminum activator effects on polyethylene branching using a N,N′‐nickel precatalyst appended with bulky 4,4′‐dimethoxybenzhydryl groups

“…The 1 H‐NMR spectra of these Ni (II) ( S = 1) complexes display broad paramagnetically shifted peaks that can be assigned through a comparison with data for related species,[4a] relative integration and closeness to the paramagnetic center (Figures S1–S10). Using Ni1 as an example, the acenaphthene protons can be identified as six distinct signals between δ 4.96 and 24.45, reflecting the presence of the two inequivalent N ‐aryl groups.…”

“…The stress–strain curves were obtained using a universal tester (Instron 1122, UK). The stress–strain recovery tests at different temperatures were carried out using a dynamic mechanical analyzer (DMA800, TA) under controlled force mode and performed as described elsewhere [4a,10]…”

“…With regard to the precatalyst, many different types of nickel (II) halide complexes have now been reported, in which the structural features of the particular chelating ligand have been found to be crucial to performance . In the case of α‐diimine precatalysts ( A , Figure ), manipulation of the ligand backbone or the substituents belonging to the N ‐aryl groups allows a means of both tuning the catalyst and the polymer microstructure.…”

Highly resilient polyethylene elastomers prepared using α‐diimine nickel catalyst with highly conjugated backbone

“…[36,37] The benzhydryl-derived α-diimine nickel catalysts developed by Long et al showed outstanding thermal stability and could form high-molecular-weight polyethylene (M n > 600 000 g mol −1 ) (Figure 1, III). [42,43] According to the FIGURE 1 Selected examples of previously reported α-diimine Ni(II) catalysts literature reports, hyperbranched polyethylene with high molecular weight can be prepared using α-diimine Ni(II) catalysts with bulky substituents on the aniline moieties. [40,41] Recently, Sun et al used a group of unsymmetric αdiimine nickel catalysts to prepare elastomeric polyethylenes that showed good elastomeric recovery and high elongation at break (Figure 1, V).…”

“…[40,41] Recently, Sun et al used a group of unsymmetric αdiimine nickel catalysts to prepare elastomeric polyethylenes that showed good elastomeric recovery and high elongation at break (Figure 1, V). [42,43] According to the FIGURE 1 Selected examples of previously reported α-diimine Ni(II) catalysts literature reports, hyperbranched polyethylene with high molecular weight can be prepared using α-diimine Ni(II) catalysts with bulky substituents on the aniline moieties. However, such bulky substituents were found to reduce the branching density of polyethylenes compared with B-Cat.…”