Copolymerization of ethylene with methyl methacrylate by ziegler-natta-type catalysts based on nickel salicylaldiminate/methylalumoxane systems

Abstract

Bis(salicylaldiminate)nickel(II) complexes, such as bis[N(2,6‐diisopropylphenyl) salicylaldiminate]nickel(II) and bis(N‐isopropylsalicylaldiminate)nickel(II), were activated by methylalumoxane (MAO) to give catalytic systems able to copolymerize ethylene (E) with methyl methacrylate (MMA), thus producing low molecular weight copolymers with a rather high content of MMA co‐units (50–80 mol‐%). On the contrary, when catalytic systems, obtained by oxidative addition of salicylaldimine ligands such as 5‐nitro‐N‐(2,6‐diisopropylphenyl)salicylaldimine (NPS) and 3,5‐dinitro‐N‐(2,6‐diisopropylphenyl)salicylaldimine (DNPS) to bis(cyclooctadienyl)nickel(0) [Ni(cod)2], were activated with MAO, high viscometric average molecular weight (Mv 10–30 × 104 Da) E/MMA copolymers with a low content of MMA co‐units (3–6 mol‐%) were formed, thus allowing to obtain directly by synthesis functionalized highly linear poly(ethylene)s (Tm up to 130 °C) to be potentially applied as new materials with improved surface properties.

Linear low-density polyethylenes by co-polymerization of ethylene with 1-hexene in the presence of titanium precursors and organoaluminium co-catalysts

“…Gas chromatography (GC) for the analysis of oligomeric products was performed on a Series II HewlettePackard 5890, equipped with a HP 3396 integrator, as previously reported [33]. GC/mass spectrometry (MS) analysis was carried out employing a HP5973 Mass Selective Detector and a HP6890 Series GC system, equipped with a HP5-MS crosslinked 5% phenylmethylsiloxane column (30 m  0.25 mm  0.25 mm).…”

Ethylene polymerization by bis(salicylaldiminate)nickel(II)/aluminoxane catalysts

“…An analogous active species is supposed to be formed “ in situ ” without the isolation of VI by means of the oxidative addition of the free salicylaldimine ligand to Ni(cod) 2 and by direct treating of the resulting intermediate with MAO under ethylene. The above system was found to be active also in the copolymerization of E with methyl methacrylate to afford functionalized PE with a low content of methyl methacrylate co‐units, potentially useful as material with improved surface properties 12…”

Polymerization of methyl methacrylate catalyzed by mono-/bis-salicylaldiminato nickel(II) complexes and methylaluminoxane

“…In the present of MAO, this type of catalysts can catalyze MMA polymerization [15,16] as reported by Carlini group. In the case of bis(3,5-dinitro-salicylaldiminato)nickel(II), the productivity was rather low, while under an ethylene atmosphere, high activity around 150000 g PMMA/(mol Ni$h) was observed [17].…”