Polymerization of vinyl ethers with transition‐metal catalysts: An examination of the stereoregularity of the formed polymers

Abstract

The polymerization of isobutyl vinyl ether (IBVE) and tert‐butyl vinyl ether (TBVE) was carried out with metallocene and nonmetallocene catalysts, and the stereoregularity of the formed polymers was examined with 13C NMR spectroscopy. IBVE afforded polymers with 63–68% dyad isotacticity by polymerization with mixtures of metallocene catalysts and methyl aluminoxane as a cocatalyst in toluene as a solvent. However, TBVE yielded polymers with 47–52% dyad isotacticity (21–28% triad isotacticity) under the same conditions, the isotacticity being lower than that of poly(isobutyl vinyl ether) (PIBVE). Nonmetallocene catalysts, including Ti, Zr, and Hf complexes with two phenoxy imine chelate ligands, provided PIBVE and poly(tert‐butyl vinyl ether) with 63–68 and 45–51% dyad isotacticity, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3938–3943, 2002

Polymerization of Vinyl Ethers by (α‐diimine)NiII/Methylaluminoxane Catalysts

“…The propagating cationic chain ends are stabilized by MAO, preventing chain termination. Similar results have been reported for the vinyl ether polymerizations by metallocene catalysts [9] and early transition metal complexes [12] containing phenoxy imine chelate ligands in the presence of MAO, and by cationic palladium imine complexes. [13] Neutral palladium complexes showed no catalytic activity like the present Ni II complexes.…”

“…The similar yield behavior according to the Scheme 1. bulkiness of catalyst was reported for the IBVE polymerization by the Group 4 phenoxy imine catalyst. [12] In a separate IBVE polymerization run by catalyst b (entries 9-13), 1 mL of the samples was taken at prescribed times given in Table 1 and characterized. The M n value sharply increased during the early period of polymerization (M n ¼ 9 000 at 0.5 h) to an almost asymptotic value, even if the yield was only 3.75%.…”

“…[1,2] Vinyl ether monomers containing electrondonating groups can be cationically polymerized by utilizing Lewis acid due to the resonance stabilization of carbocations by lone pair electrons on the oxygen. [3][4][5][6] Some studies have been reported to control the stereoregularity in vinyl ether polymerization by using special Ziegler-type catalysts, [7,8] metallocene catalysts, [9][10][11][12] and postmetallocene catalysts. [12] Even if the cationic late transition metal complexes are known to be remarkably functional group tolerant, [1,2] late transition metal complexes are rarely reported.…”

“…[3][4][5][6] Some studies have been reported to control the stereoregularity in vinyl ether polymerization by using special Ziegler-type catalysts, [7,8] metallocene catalysts, [9][10][11][12] and postmetallocene catalysts. [12] Even if the cationic late transition metal complexes are known to be remarkably functional group tolerant, [1,2] late transition metal complexes are rarely reported. [1,2,13] Liu and co-workers [13] used a series of cationic palladium diimine complexes as catalysts for the polymerization of vinyl ethers in high yield, finding that the p-acidic character of imine donors increases the activity of the palladium metal center.…”

A stepping stone to stereospecific living cationic polymerization: Cationic polymerization of vinyl ethers using iron(II) sulfate

“…18 This catalyst system is the first example of the stereoregulation by the precise design of catalyst ligands in homogeneous systems in cationic polymerization. Other recent studies in homogeneous systems include polymerization using metallocene catalysts with Group 4 metals [19][20][21] and titanium catalysts with tridentate triamine ligands. 22 Recently, our group has developed initiating systems for living cationic polymerization of VEs utilizing soluble metal halides with a variety of central metals by combining suitable types of additives.…”