Access through your institution Buy or subscribe In addition to modification of ligands, the addition of salts or Lewis acids has also been shown to improve catalyst performance. Since 2012,

Jordan et al. found that the addition of Lewis acids alters the polymerization activity and molecular weight of the product when catalyzed by palladium complexes bearing

phosphine–sulfonate, phosphinite, or phosphonite (Fig. 1, left middle) [6]. Modification of palladium/phosphine–sulfonate complexes by B(C6F5)3 increased the polymerization activity but

decreased the molecular weight, while B(C6F5)3 modification of palladium/phosphine–phosphonate increased both the molecular weight of the polymer and polymerization activity. The addition of

was bound to nickel/salicylaldimine-type catalyst 2 (Fig. 1, left bottom) [7]. Catalyst 2 with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF4) showed 20-fold higher

polymerization activity and a threefold higher molecular weight than the obtained polymer. Other BArF4 salts did not affect the catalyst properties. However, it should be noted that _all of

these studies on the additive effect are limited to ethylene homopolymerization in nonpolar solvents in the absence of any polar functional groups_. In 2017, Chen et al. examined the

copolymerization of ethylene and methyl acrylate (E/MA) with palladium/phosphine–sulfonate complexes bearing oligoethylene glycol moieties bound to the diarylphosphine part [3b]. The higher

incorporation of MA with the polyethylene moiety was explained by the increase in local polarity around the palladium center, but no further studies on the salt effect have yet been reported

for copolymerization. We hypothesized that the addition of salts near the central metal would accelerate the insertion of acrylates by the interaction of polar monomers and cations (Fig. 1,

right). As a result, the addition of lithium borate salt increased the polymerization activity and decreased the molecular weight without decreasing the incorporation of MA into the

copolymer, as described below. This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 12

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Influences in Phosphinesulfonato Palladium(II) Polymerization Catalysts. Organometallics 2013;32;4516–22. Download references ACKNOWLEDGEMENTS The authors are grateful to Prof. Shingo Ito

(Nanyang Technological University) and Prof. Ryo Nakano (Nagoya University) for helpful discussions. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Chemistry and Biotechnology,

Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, Japan Shumpei Akita & Kyoko Nozaki Authors * Shumpei Akita View author publications You can also search for

this author inPubMed Google Scholar * Kyoko Nozaki View author publications You can also search for this author inPubMed Google Scholar CORRESPONDING AUTHOR Correspondence to Kyoko Nozaki.

ETHICS DECLARATIONS CONFLICT OF INTEREST The authors declare no competing interests. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer Nature remains neutral with regard to jurisdictional

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Akita, S., Nozaki, K. Copolymerization of ethylene and methyl acrylate by palladium catalysts bearing IzQO ligands containing methoxyethyl ether moieties and salt effects for

polymerization. _Polym J_ 53, 1057–1060 (2021). https://doi.org/10.1038/s41428-021-00500-3 Download citation * Received: 13 February 2021 * Revised: 24 March 2021 * Accepted: 19 April 2021 *

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