Kinetic and Mechanistic Aspects of Ethylene and Acrylates Catalytic Copolymerization in Solution and in Emulsion

Abstract

Ethylene was copolymerized with acrylates in solution and in emulsion using sulfonated arylphosphine Pd-based catalysts. The copolymerization of C 2 H 4 and methyl acrylate in toluene was slowed by the σ-coordination of the acrylate on Pd. The substitution of pyridine by itself was shown to proceed via an associative mechanism with activation parameters ΔH ‡ =16.8 kJ/mol and ΔS ‡ =-98 J mol -1 K -1 whereas the activation parameters for the substitution of pyridine by methyl acrylate were found to be ΔH ‡ =18.1 kJ/mol and ΔS ‡ =-87 J mol -1 K -1 . Using these Pd-based catalysts in an emulsion polymerization process, latexes of copolymers of ethylene with various acrylates having particle diameters ∼200 nm were obtained for the first time. Their solid contents did not exceed 5% because of the low activity of the catalyst resulting from the coordination of water and from the slow decomposition of the active site by water.

Structure–Activity Relationship of Palladium Phosphanesulfonates: Toward Highly Active Palladium‐Based Polymerization Catalysts

“…3 10 À2 mol L À1 in CDCl 3 ) is contacted with pyridine (0.45 equiv), lutidine is displaced quantitatively by pyridine, as expected for steric reasons (shorter Pd À N bonds for related pyridine complexes (except for complex 2 f-pyr; see Table 1). This ligand substi- , see the Supporting Information) as we [9] and Conley et al [16] have shown that ligand exchange occurs through an associative bimolecular pathway for palladium phosphanesulfonates. This relatively low value of k contrasts with the value of 2.3 10 5 L mol À1 s reported by us for pyridine exchange at 4 8C for catalyst 2 a-pyr.…”

“…This relatively low value of k contrasts with the value of 2.3 10 5 L mol À1 s reported by us for pyridine exchange at 4 8C for catalyst 2 a-pyr. [9] For 2 a-pyr, free pyridine is in rapid exchange with bound pyridine at room temperature (coalescence at À50 8C), as observed by 1 H NMR spectroscopy, whereas for catalyst 2 h-pyr, free pyridine and bound pyridine are in the slow exchange regime at 50 8C. For catalyst 2 f-pyr, coalescence is not yet reached at room temperature in CDCl 3 , and coalescence between free and bound pyridine occurs at 60 8C in C 2 D 2 Cl 4 (the Supporting Information).…”

“…Thus, the catalyst based on phosphane bis-tert-butyl-phosphanyl-benzenesulfonic acid (R = tBu) exhibits unprecedented high activity, rapidly polymerizing ethylene at room temperature to yield a linear polymer of high molecular weight (M w = 116 000 g mol improvement in activity. [9] In practice, the improvement may not be that large, as the catalyst is never base-free (even the toluene solvent can coordinate). For example, Guironnet et al [7] have demonstrated that, under similar conditions, the activity of Drent catalysts bound to DMSO and to pyridine are 1150 and 620 g PE mmol Pd À1 h…”

“…[4i, 7,9] These exhaustive data were obtained with ligands 1 a, 1 b, and 1 f, and they have not all been included in Table 3. In brief, to reach a high MA incorporation, it is necessary to use the lowest ethylene pressure and the highest MA concentration possible during the reaction.…”

Investigation of Steric and Electronic Factors of (Arylsulfonyl)phosphane‐Palladium Catalysts in Ethene Polymerization

“…[15] These studies employ the catalyst [(oAr 2 PC 6 H 4 SO 3 )PdMe(L)] with Ar = o-OMePh, which corresponds to the ligand originally presented by Drent. [5] The role of the ancillary ligand L (L = pyridine, [12,16] lutidine, [17] DMSO, [15] or allyl group [11] ) on the catalytic activity has been studied in detail. However, at this time, little is known on the influence of the arylphosphane sulfonate structure.…”