Cyanoacrylates super glue

Polymers are also used as sutures. Fighters and other athletes have used poly(alpha-cyanoacrylates), super glues, to quickly stop blood flow in surface cuts. Today, super glue is also used for, in place of or along with, more traditional polymeric suture threads for selected surface wounds, internal surgery, and retinal and corneal surgery. The alpha-cyanoacrylate polymers (structure 19.22) undergo anionic polymerization in the presence of water. More about sutures is explained in Section 19.6. 

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. 

SYNS ADHERE COAPT a-CYANOACRYLIC ACID METHYL ESTER 2-CYANOACRYLIC ACID, METHYL ESTER CYANOLIT E. STMAN 910 EASTMAN 910 ADHESIVE EASTMAN 910 MONOMER MECRILAT MECRYLATE METHYL CYANOACRYLATE METHYL 0-CYANOACRYLATE SUPER GLUE... 

During the transformation of a monomer into a polymer, many atoms separated by van der Waals distances ( 5 A) participate in the formation of covalent bonds (1-3 A). Therefore during polymerization, an increase in the macroscopic density ensues, while on the molecular level a decrease in free volume and entropy occurs while the cooperativity of motions increase. Concomitantly the glass temperature can increase by more than 100 °C. Several important adhesive systems are based on this increase. The cyanoacrylate Super Glue starts as a monomer with a Tg <0 °C and it polymerizes to a linear soluble polymer with a Tg which is in the neighborhood of 100 °C upon appUcation under anaerobic conditions. For linear polymers the simple equation [74]... 

The a-alkyl cyanoacrylate super glues ( one drop holds 5000 lbs ) are now a familiar part of the consumer market. Originally, the monomers had extremely low viscosities and so could crawl into narrow crevices and wet the adherend surfaces rapidly. On the other hand, they would not fill gaps and were absorbed into porous adherends, giving poor bonds. Newer versions are available with higher viscosities to overcome these drawbacks. Cyanoacrylates can polymerize in seconds by an anionic addition reaction believed initiated by hydroxyl ions from water adsorbed on the adherend surfaces ... 

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. 

The alkyl 2-cyanoacrylates have become well-known adhesives, often popularly known as super-glue. 

Acrylic adhesives cure by a free radical chain growth mechanism. In contrast, epoxy and urethane adhesives cure by a step growth mechanism. This has a major impact on the cure kinetics, as well as the composition of the adhesive during cure ([9], pp. 6-9). Cyanoacrylate adhesives (such as Super Glue ) also cure by chain growth, but the mechanism is ionic with initiation by surface moisture. 

Cyanoacrylate adhesives, the famous consumer Super glue , is a monomer that polymerizes when it comes in contact with moisture, even with atmospheric moisture. 

Alkyl-2-cyanoacrylates are readily polymerized in the presence of weak bases such as water. Because of the presence of the strong polar cyano pendant group these polymers (e.g. Super Glue) are excellent adhesives. Polybutyl-2-cyanoacrylate is tolerated by the body better than its lower alkyl homo-logues. Hence polybutyl-2-cyanoacrylate is used as an adhesive aid to stop bleeding in some surgical operations. 

Cyanoacrylate glue (Super Glue or Krazy Glue). 

Super glue is a polymer of methyl cyanoacrylate. Because both the cyano and carbonyl groups of the monomer help stabilize carbanions, this compound is sensitive to polymerization by the anionic mechanism. The tube of glue contains very pure monomer, which does not polymerize until it contacts an initiator. However, contact with any nucleophile causes rapid polymerization. Therefore, when the tube is opened, polymerization is initiated by water in the air, by SiOH groups on a glass surface, by FeOH groups on an iron surface, or by various nucleophiles that are part of the proteins in skin. The adhesion between the polymer and the surface to which it is applied is very strong because the polymer chains are covalently linked to the nucleophiles that are part of the surface ... 

Super glue, that instant adhesive used for so many jobs around the house, illustrates ionic chain polymerization beautifully. The glue contains a cyanoacrylate monomer that polymerizes by an anionic mechanism. Even a trace of water or OH group (for example, that found on your skin) causes an extremely rapid polymerization forming a rigid plastic bonded to the surface(s) on which it polymerized. 

A special-purpose adhesive that forms an exceedingly strong bond to metals and many other materials, including careless experimenters, is cyanoacrylate contact cement, available as Eastman 910 Adhesive and Super Glue (Woodhill Chemical). It is expensive, but only small amounts are needed. In this cement, the material polymerizes rapidly without an added activator. It is not void filling, and a 0.001 in.-thick film yields the best bond. Do not buy more than you will need in a few months since it slowly deteriorates store in the refrigerator. 

CYANON 5MSP CYANON S DA 737S 910EM ETHYL a-CYANOACRYLATE ETHYL 2-CYANO-ACRYLATE ETHYL 2-CYANO-2-PROPENOATE N 135 2-PROPENOIC ACID, 2-CYANO-, ETHYL ESTER PTR-E 3 PTR-E 40 SICOMET 8400 SUPER 3-1000 SUPER GLUE TK 200 TK 201... 

Cyanoacrylate adhesives (Krazy glue, Super glue) are common household products. They are packaged similar to topical ocular preparations and therefore have accidentally been instilled into the eye. Although these adhesives typically do not cause serious harm, they can and are the cause of significant anxiety when accidents occur. 

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