Custom-made polar monomers utilized in nickel and palladium promoted olefin copolymerization

Abstract

The functionalization of polyolefins through copolymerization of olefin and polar monomers catalyzed by late transition metals such as nickel and palladium is of academic and industrial significance. In recent years,...

Vanadium-Catalyzed Terpolymerization of α,ω-Dienes with Ethylene and Cyclic Olefins: Ready Access to Polar-Functionalized Polyolefins

“…The homopolymerization of 1,5-hexadiene formed a soluble, solid polymer with a M w of 47 × 10 3 g mol −1 , a rather narrow molecular weight distribution (M w /M n = 2.3), and a T g of −17 °C. The polymer characterization by 1 H and 13 C NMR revealed a high degree of unsaturation and the presence of three types of polymer chain fragments: methylene-1,3cyclopentane units (referred to "MCP"), 3-vinyl-tetramethylene units (referred to "VTM"), and linear C6 segments with an internal CC bond (referred to "INT") (Figures S4 and S5 and Table S3). 28 Overall, the NMR data indicate that c1 exhibits regio-random insertion of 1,5-hexadiene, that is, it does not have a significant selectivity for 1,2-versus 2,1- 59 To be noted, the pendant 3butenyl group, expected from successive 1,2-insertion of 1,5hexadiene (Scheme 1, path A), was not observed: 1,2-insertion is preferentially followed by ring closure that evolves into a MCP unit (Scheme 1, path C).…”

“…Figure 3a shows the whole 13 C NMR spectrum, and methylene and methine carbons were distinguished by DEPT (Figure S7). In addition to the characteristic peaks of long methylene segments (S δδ at 27.7 ppm), the 13 C NMR spectrum shows the resonances ascribed to trans (referred to 1t−5t) and cis (referred to 1c−5c) MCP fragments and those to unsaturated VTM ones (referred to v1−v5, Table S4). NMR analysis established that the copolymer is formed by 77.9 mol % of ethylene, 18.9 mol % MCP, and 3.2 mol % VTM.…”

“…Peak assignment was carefully performed by comparison of the observed chemical shifts with those of entry 3 (Figure 3a and Table S5) and the previous data by some of us. 41 Figure 4 shows the 13 C NMR spectrum of the E/HXD/NB terpolymer along the various types of monomer enchained fragments identified. In addition to the characteristic peaks of isolated and alternated NB units from the addition type copolymerization with cis exo−exo enchainment (i.e., 44.7−45.7 ppm (C2/C3); 39.0−40.0 ppm (C1/C4); 30.9 ppm (C7); and 27.0−29.0 ppm (C5/C6 and ethylene CH 2 )), the spectrum shows resonances diagnostic of isolated MCP and VTM units from 1,2-(Scheme 1, path C) and 2,1-insertion (Scheme 1, path B) of 1,5-hexadiene, respectively.…”

“…The 13 C and 1 H NMR spectra of E/HXD/ENB terpolymer are shown in Figures 5 and S8, respectively. In addition to the signals ascribed to VTM and MCP units, the 1 H NMR spectrum shows signals at 5.1 and 5.3 ppm that were assigned to the ethylidene groups, while the lack of signals at about 6.0 ppm indicates that ENB inserts into the polymer chain via the enchainment of the double bond of the norbornenic ring, while S6).…”

“…Therefore, the synthesis of specialty polyolefins with unsaturated reactive groups and functionality is a key target. − It is expected that the direct introduction of a few percent of functional groups may enlarge the scope of polyolefins to construct engineering materials. In this respect, the insertion copolymerization of olefins with polar comonomers − and the post-polymerization modification are a highly sought-after area of research. − Polyolefins having pendant CC groups are valuable and promising candidates: the modification of reactive polyolefin intermediates is a profitable and easy alternative to the copolymerization of polar monomers. It exploits the reactivity of double bonds, including thiol-ene ligations, epoxidation, and hydrosilylation. − …”