Methyl-a-cyanoacrylate

The adhesive marketed under the tradename Superglue contains the monomer methyl a-cyanoacrylate (Fig. 14.5.1). A variety of cyanoacrylates are commercially sold as contact adhesives with the alkyl group -R denoted in Fig. 14.5.2 varying from a methyl group to produce ethyl, isopropyl, allyl, butyl, isobutyl,... 

Figure 14.5.1 The monomer methyl a-cyanoacrylate found in the adhesive marketed under the trademark Superglue. ...

Similarly, zwitterionic tetramethylenes as initiators of anionic polymerization were also observed. For example, methyl a-cyanoacrylate polymerizes via an anionic mechanism in the presence of n-butyl vinyl ether [90]. A Diels-Alder adduct is also formed. In another example, the reaction of isobutyl vinyl ether and nitroethylene leads to an unstable adduct [91], which is capable of initiating the anionic polymerization of excess nitroethylene, and also the cationic polymerization of added VCZ. 

Spontaneous 1 1 copolymerization has been noted when sulfur dioxide was bubbled through bicycloheptene at —40°C. (88), when isobutylene was bubbled through methyl a-cyanoacrylate (54), when 1,3-dioxole was mixed with maleic anhydride (17), and when vinylidene cyanide was mixed with styrene (20), the latter reactions at room temperature. None of these monomers undergoes homopolymerization under the same experi-... 

Suggest which of the following monomers might polymerize well on treatment with BF3. (a) vinyl chloride (b) vinyl acetate (c) methyl a-cyanoacrylate... 

Methyl a-cyanoacrylate (Super Glue) is easily polymerized, even by weak bases. Draw a mechanism for its base-catalyzed polymerization, and explain why this polymerization goes so quickly and easily. 

Synthetic polymers can be classified as either chain-growth polymers or step-growth polymers. Chain-growth polymers are prepared by chain-reaction polymerization of vinyl monomers in the presence of a radical, an anion, or a cation initiator. Radical polymerization is the most commonly used method, but alkenes such as 2-methylpropene that have electron-donating substituents on the double bond polymerize easily by a cationic route. Similarly, monomers such as methyl a-cyanoacrylate that have electron-withdrawing substituents on the double bond polymerize by an anionic (Michael reaction) pathway. 

Because poly(methyl a-cyanoacrylate) degrades relatively rapidly to methyl a-cyanoacrylate, which is an intensely necrotizing and pyogenic compound (25. 26). polymerization of this compound is clearly not a viable surgical procedure. However, higher a-cyanoacrylate esters are considerably less toxic, and polymer degradation occurs at a much lower rate so that these materials may have potential as surgically useful materials (27. 28. 29). 

Contraception. The rapid polymerization of methyl a-cyanoacrylate and its effect on living tissue has been utilized in female sterilization by oviduct blockage (30). In this procedure methyl a-cyanoacrylate is instilled into the oviduct where it rapidly polymerizes into a solid. Subsequent degradation of the polymer leads to formation of scar tissue, which eventually permanently blocks the oviduct. The overall process is shown in Figure 6 (31). 

Poly(methyl a-cyanoacrylate) Poly(4-methyl-1 -pentene)... 

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