Ethylene/methyl acrylate copolymerization

Scheme 2 Proposed mechanism for ethylene/methyl acrylate copolymerization...

Scheme 10 Activity reduction in ethylene-methyl acrylate copolymerizations due to the formation of stable chelate 1.30...

MOLECULAR DYNAMICS IN THE STUDIES OF THE ETHYLENE - METHYL ACRYLATE COPOLYMERIZATION... 

Figure 4-22. Mechanism of ethylene-methyl acrylate copolymerization monomer insertion...

Michalak A, Ziegler T, DFT Studies on the Copolymerization of a-Olefins with Polar Monomers Ethylene-Methyl Acrylate Copolymerization Catalyzed by a Pd-based Diimine Catalyst, J Am Chem Soc, 123, 12266-12278 (2001)... 

Toughened cyanoacrylate adhesives containing random copolymeric elastomers have been patented. The only elastomer whose performance has been quantified is an ethylene-methyl acrylate copolymer sold by Du Pont under the name Vamac B-124. Several other elastomers are said to be useful tougheners, but no details have been given beyond solubility data. 

Fig. 2. Relationship between relative rate and monomer composition in the copolymerization of DAP with vinyl monomers A, styrene or methyl methacrylate B, methyl acrylate or acrylonitrile C, vinyl chloride D, vinyl acetate, and E, ethylene (41).

Polymer Composition. Ethylene—acrylic elastomer terpolymers ate manufactured by the addition copolymerization of ethylene [74-85-1] and methyl acrylate [96-33-3] in the presence of a small amount of an alkenoic acid to provide sites for cross-linking with diamines (4). 

The diimine palladium compounds are less active than their nickel analogs, producing highly branched (e.g., 100 branches per 1,000 carbons) PE. However, they may be used for the copolymerization of Q-olefins with polar co-monomers such as methyl acrylate.318,319 Cationic derivatives, such as (121), have been reported to initiate the living polymerization of ethylene at 5°C and 100-400 psi.320 The catalyst is long-lived under these conditions and monodisperse PE (Mw/Mn= 1.05-1.08) may be prepared with a linear increase in Mn vs. time. 

The Lewis acidity and reactivity of these alkyl aluminum cocatalysts and activators with Lewis basic polar monomers such as acrylates make them impractical components in the copolymerization of ethylene with acrylates. To address this shortcoming, Brookhart et al. developed well-defined cationic species such as that shown in Fig. 2, in which the counterion (not illustrated) was the now-ubiquitous fluorinated arylborate family [34] such as tetrakis(pentaflurophenyl)borate. At very low methyl acrylate levels the nickel catalysts gave linear copolymers but with near-zero levels of acrylate incorporation. 

The cationic Pd(II) catalysts exhibit effective copolymerizations of ethylene and other a-olefins with polar-functionalized comonomers, with the majority of insertions occurring at the ends of branches. Among the best tolerated monomers are those bearing fluorine or oxygen-containing functionalities, such as esters, ketones, and ethers. The copolymerization of ethylene and acrylates, attractive because the monomers are inexpensive and the copolymers exhibit unique physical properties, has been well-studied mechanistically [27,69], Examples of copolymerizations of ethylene and a-olefins with methyl acrylate are shown in Table 4. In general, the amount of comonomer incorporation varies linearly with its reaction concentration and... 

Table 4 Copolymerizations of ethylene and a-olefins with methyl acrylate (MA) by Pd(II) a-diimine catalysts3...

Mecking S, Johnson LK, Wang L, Brookhart M, Mechanistic Studies of the Palladium-Catalyzed Copolymerization of Ethylene and -Olefins with Methyl Acrylate, J Am Chem Soc, 120, 888-899 (1998)... 

In later communications (27, 28) Hirooka reported that in addition to acrylonitrile, other conjugated monomers such as methyl acrylate and methyl methacrylate formed active complexes with organoaluminum halides, and the latter yielded high molecular weight 1 1 alternating copolymers with styrene and ethylene. However, an unconjugated monomer such as vinyl acetate failed to copolymerize with olefins by this technique. 

Unlike early transition metal polymerization catalysts which do not tolerate functional groups, cationic palladium complexes are able to copolymerize ethylene with methyl acrylate.128... 

Goodall (12) disclosed late transition metal catalysts that are highly active and are capable of copolymerizing ethylene with polar comonomers, such as acrylic acid and methyl acrylate. Moreover, Goodall catalysts do not require cocatalysts. An example of a Goodall catalyst is provided in Figure 6.6. 

A similar inhibition, but not cessation, of polymerization was observed by Brookhart in his work on the copolymerization of ethylene with methyl acrylate that is catalyzed by cationic bisimine-Pd(II) complexes [9]. Here again, the coordination of the oxygen atom of the ester group of acrylate significantly slows down polymerization and leads to lower molecular weight materials (Eq. (3)). 

Brookhart and co-workers recently reported tantalizing results that were close to constituting true copolymerizations of ethylene and methyl acrylate. ° ° The catalyst employed was the palladium version of the diimine complexes that were previously reported for ethylene and a-olefin homopolymerizations (complexes IV). °° The close qualification... 

Scheme 6. Illustration of Results from Low-Temperature NMR Mechanistic Studies of the Copolymerization of Ethylene and Methyl Acrylate ...

CnRhMe(OH)2 is not a catalyst. One polyethylene sample formed in water had a Mv of 5100 and a polydispersity index of 1.6 the average turnover rate was 1 per day. It is possible to copolymerize ethylene with polar comonomers such as methyl acrylate with the rhodium catalysts. In addition to the Cn ligands, softer trithiocyclononane ligands support the polymerization of ethylene on both rhodium and platinum. 

The functional-group tolerance of late metal catalysts is evident, particularly in the copolymerization of ethylene and methyl acrylate by the a-diimine palladium catalysts. 

Figure 17 presents the energy profiles for the methyl acrylate insertion into the Pd-alkyl and Ni-alkyl bond in the generic diimine systems [31,32]. The results clearly indicate that it is not the insertion barrier which makes the Ni-system inactive in polar copolymerization. The acrylate insertion barrier is substantially lower for the Ni-catalyst then for the Pd-complex. This, in fact, should not be surprising, as the ethylene insertion barriers are also lower for the Ni-system. 

Ethylene copolymers with acrylates represent a significant segment of the ethylene copolymer market, as many LDPE producers use copolymerization as a strategy to obtain products more resistant to displacement by HOPE and LLDPE. Ethylene copolymers with methyl methacrylate and ethyl, butyl, and methyl acrylates are similar to EVA copolymers in properties (discussed later) but have improved thermal stability during extrusion and increased low-temperature flexibility. 

Litt, M. and Seiner, J.A., The role of monomer charge transfer complexes in free radical copolymerization III. Methyl acrylate diphenyl ethylene copolymers. Comparison with penultimate model. Macromolecules, 4, 308 (1971). 

To explore the possibilities of olefin polymerization in SCCO2, several monomer and catalyst systems have been investigated. Initially, the proof of principle was established by the polymerization of 1-hexene using the Brookhart catalyst in SCCO2. Subsequently, the polymerization of ethylene was studied in detail. Finally, the copolymerization of ethylene with methyl acrylate was assessed. 

In this section, the polymerization of ethylene and a functional monomer is discussed. For this purpose copolymerization reactions of methyl acrylate (MA) and ethylene using a palladium-based catalyst have been carried out in compressed carbon dioxide at different monomer concentrations and monomer ratios. The incorporation of methyl acrylate and the molecular weight of the polymers have been compared to literature values of polymerizations conducted in dichloromethane. 

Catalyst precursor 2 as shown in Fig. 8.4 was used for the copolymerization reactions of ethylene and methyl acrylate (0.05 mmol catalyst/L) [9, 41]. The in-... 

I g Catalytic Polymerization of Ol ns in Supercritical Carbon Dioxide Table 8.11 Results of copolymerizations of ethylene and methyl acrylate in compressed carbon dioxide. 

Sdierman and co-workers recently utilized CB[8] ternary complexation for the conjugation of small molecules to a polymeric backbone in water. The authors used RAFT polymerization to copolymerize a 2-naphthol-functional acrylate monomer with poly[oligo(ethylene glycol)]acrylate to form a water-soluble, 2-naphthol pendant acrylate copolymer. By using UV-Vis spectroscopy and multidimensional NMR techniques, the authors could determine that several methyl viologen (MV)-functional units could be noncovalently... 

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