Anionic polymerization, ethyl

Cyanoacrylate adhesives (Super-Glues) are materials which rapidly polymerize at room temperature. The standard monomer for a cyanoacrylate adhesive is ethyl 2-cyanoacrylate [7085-85-0], which readily undergoes anionic polymerization. Very rapid cure of these materials has made them widely used in the electronics industry for speaker magnet mounting, as weU as for wire tacking and other apphcations requiring rapid assembly. Anionic polymerization of a cyanoacrylate adhesive is normally initiated by water. Therefore, atmospheric humidity or the surface moisture content must be at a certain level for polymerization to take place. These adhesives are not cross-linked as are the surface-activated acryhcs. Rather, the cyanoacrylate material is a thermoplastic, and thus, the adhesives typically have poor temperature resistance. 

In polymerizing these compounds, a reaction between a-TiCls and triethylaluminum produces a five coordinate titanium (111) complex arranged octahedrally. The catalyst surface has four Cl anions, an ethyl group, and a vacant catalytic site ( ) with the Ti(lll) ion in the center of the octahedron. A polymerized ligand, such as ethylene, occupies the vacant site ... 

Penultimate effects have been observed for many comonomer pairs. Among these are the radical copolymerizations of styrene-fumaronitrile, styrene-diethyl fumarate, ethyl methacrylate-styrene, methyl methacrylate l-vinylpyridine, methyl acrylate-1,3-butadiene, methyl methacrylate-methyl acrylate, styrene-dimethyl itaconate, hexafluoroisobutylene-vinyl acetate, 2,4-dicyano-l-butene-isoprene, and other comonomer pairs [Barb, 1953 Brown and Fujimori, 1987 Buback et al., 2001 Burke et al., 1994a,b, 1995 Cowie et al., 1990 Davis et al., 1990 Fordyce and Ham, 1951 Fukuda et al., 2002 Guyot and Guillot, 1967 Hecht and Ojha, 1969 Hill et al., 1982, 1985 Ma et al., 2001 Motoc et al., 1978 Natansohn et al., 1978 Prementine and Tirrell, 1987 Rounsefell and Pittman, 1979 Van Der Meer et al., 1979 Wu et al., 1990 Yee et al., 2001 Zetterlund et al., 2002]. Although ionic copolymerizations have not been as extensively studied, penultimate effects have been found in some cases. Thus in the anionic polymerization of styrene t-vinylpyri-dine, 4-vinylpyridine adds faster to chains ending in 4-vinylpyridine if the penultimate unit is styrene [Lee et al., 1963]. 

Foster, W. E. Anionic polymerization process. United States Patent 2,841,574 (to Ethyl Corporation) July 1, 1958. 

Anionic polymerization of (meth)acrylates with hindered ester functions can most likely be conducted at room temperature and above to remove the heat of polymerization with low boiling solvents. Polymerization of the important methyl and ethyl (meth)acrylate members of the family, however, are still plagued by chain termination at higher temperatures. The phosphorus based counterions have a stability advantage over tetraalkylammonium counterions which undergo Hoffman elimination. 

Nakayama, Tsututa, Furuakawa and Kawasaki (46) have studied the stereospecific anionic polymerization of a series of alkyl thioacrylates. They found that the M-propyl, i-propyl, w-butyl, i-butyl, -sec.-butyl, and /-butyl thioacrylates gave crystalline polymer. The ethyl compound gave amorphous polymer. 

Indole with benzoyl nitrate at low temperatures gives 3-nitroindole this can also be obtained by reaction of the indolyl anion with ethyl nitrate. More vigorous conditions can be used for the nitration of 2-methylindole because of its resistance to acid-catalyzed polymerization. In nitric acid alone it is converted into the 3-nitro derivative, but in a mixture of concentrated nitric and sulfuric acids 2-methyl-5-nitroindole is formed, by conjugate acid nitration (see Section 3.3.3.2.1). 

The favorable effect of trialkylaluminium on the anionic polymerization of acrylic monomers induced by organolithium compounds prompted a DFT theoretical and 6Li,13C NMR study on the interaction between AlEt3 and ethyl lithioisobutyrate (EIBLi) in toluene at — 20 °C. Monomers, dimers and tetramers of 1 1 or 1 2 enolate and AlEt3 aggregates were identified (Scheme 67)286. 

An interesting characteristic of mthenocene is that it is a photoinitiator for the anionic polymerization of ethyl 2-cyanoacrylate. Solutions with millimolar concentrations of the complex in neat cyanoacrylate polymerize to a hard, plastic solid within seconds upon exposure to light. The low concentration of mthenocene required for the polymerization makes it desirable in applications such as coating and adhesives that require solvent-free solutions of monomer. ... 

Anionic polymerization of EtG leads to a new synthetic biodegradable polymer, namely poly(ethyl glyoxylate). Because of a low ceiling temperature and transfer reactions, PEtG has hydroxyl ends that can be end-capped with phenyl isocyanate. 

Polymerization or copolymerization of properly snbstitnted methacrylates is a direct and very effective strategy for the preparation of polymers grafted by a series of substituents. For instance, polymethacrylate containing amino groups was prepared by living LiCl-mediated anionic polymerization of 2-(dunethylamino)ethyl methacrylate (DMAEMA) °° and 2-(f-butylamino)ethyl methacrylate in THF at —78 °C. Mixtures of DMAEMA and tBuMA were also copolymerized . 

In contrast to GTP, certain functional groups are not tolerant of anionic polymerization, making it necessary to protect the group prior to polymerization and to deprotect after polymerization, which makes the process more complex. For example, 2-(trimethylsilyl-oxy)ethyl methacrylate and trimethylsUyl methacrylate were anionically polymerized as precursors of poly(2-hydroxyethyl methacrylate) and poly(methacrylic acid), respectively. 

Polymerization Catalysed by Acids and Bases. Carbonium ions and carbanions respectively are carriers of the chain transfer in cationic and anionic polymerizations respectively. Ionic polymerization mechanism was exploited for the synthesis of polymeric stabilizers in comparison with the free-radical polymerization only exceptionally. The cationic process was used for the synthesis of copolymers of 2,6-di-tert-butyl-4-vinylphenol with cyclopentadiene and/or for terpolymers with cyclopentadiene and isobutylene [109]. System SnCWEtsAlCla was used as an initiator. Poly(lO-vinylphenothiazin) was prepared by means of catalysis with titanium chlorides [110]. Polymers of 4-[a-(2-hydroxy-3,5-dimethylphenyl)ethyl]-vinylbenzene [111] and 3-allyl-2-hydroxyacetophenone [112] were also prepared under conditions of cationic polymerization. 

Precatalyst 4(Sm) was utilized as a standard system [60]. The mechanism follows a coordination anionic polymerization via an eight-membered transition state (Scheme 3, see p. 985). Formation of a metal enolate turned out to be essential for the initiation of the MMA polymerization and was confirmed by the initiation activity of the enolate complex [(C5H4SiMe3)2Y(OCH=CH2)]2- The rate of polymerization is directed by steric factors depending on the metal (Sm > Y > Yb > Lu) and the auxiliary ligand (Cp > Cp ). Ethyl, isopropyl and f-butyl methacrylates are also stereospecifically polymerized, but the rate of poly-... 

Anionic polymerizations of A-ethyl-2-vinyl-carbazole and A-ethyl-3-vinyl-carbazole have also been examined, and the 2-vinyl derivative shown to yield clean living systems. However, the 3-vinyl monomer is very much more reactive and polymerization must be conducted below — 60 °C to get any approximation to a living system. No quantitative information is available. 

QUIRK AND SEUNG Anionic Polymerization of Ethylate Oxide... 

Solvent and substituent effects in the anionic polymerization of a-ethyl-a-ri-butyl-6-proplolactone, EBPL, were Investigated in dimethyl sulfoxide and in N-methylpyrrolidone. In dimethyl sulfoxide,... 

Anionic Polymerization of g-Ethyl-g-Alkyl-S-Proplolactones. For comparison with the previously studied series of a-methyl-a-alkyl substituted monomers and polymers, three monomers containing a-ethyl-... 

Problem 8.10 The kinetics of sodium naphthalene initiated anionic polymerization of styrene was studied in a less polar solvent dioxane at 35°C. Using an apparatus which permitted quick mixing of the reaction components in absence of air and moisture, aliquot samples were withdrawn periodically and deactivated quickly with ethyl bromide. From the residual monomer and the average degree of polymerization of the polymer formed the following data were obtained... 

Durkee and co-workers have prepared polyferrocene block copolymers for use in catalysis.223 The reported polymers were synthesized via sequential anionic polymerization of vinylferrocene and isoprene, followed by oxidation using silver triflate. The fraction of ferrocene converted to ferrocenium was directly proportional to the amount of Ag+ added. These materials were tested for their catalytic activity toward the Michael addition reaction of ethyl-2-oxycyclopentane barboxylate and methylvinylketone. These materials showed k values similar in magnitude to the rates of iron(III) chloride. 

Anionic polymerization of thiiranes, e.g. 2-methyl-2-ethyl thiirane27, initiated by carbazyl or fluorenyl salts in tetrahydrofuran, also yields living polymers, see p. 152. 

Although a conventional initiation of anionic polymerization by alkyl lithiums involves their addition to a C=C bond, an exceptional mode of initiation associated with ring-opening polymerization was reported by Morton and Kammereck186). Ethyl lithium seems to initiate polymerization of propylene sulphide, but the reaction involves first a desulphuration of the monomer, leading to the formation of lithium mercaptide ... 

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