Cyanoacrylate

OVERVIEW

Cyanoacrylate (sye-AN-oh-ACL-ri-late) is a general term used to describe a family of esters derived in the reaction between cyanoacrylic acid and various alcohols, such as methanol (methyl-2-cyanoacrylate) and ethanol (ethyl-2cyanoacrylate). Cyanoacrylates are all esters of cyanoacrylic acid, CH₂=C(CN)COOH, and include methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate, and 2-octyl cyanoacrylate. The material is the primary ingredient in Super Glue™, Krazy Glue™, Duro™, Quick Gel™, and a number of other products used to glue two surfaces together with a very strong bond in a matter of seconds. The bonding activity of the cyanoacrylates occurs when the esters react with water to form polymers that bond to materials with which they come into contact. The polymerization reaction occurs very quickly, resulting in strong bonds that form almost instantaneously.

KEY FACTS

OTHER NAMES:

See Overview; data below are for the methyl ester.

FORMULA:

CH₂=C(CN)COOCH₃

ELEMENTS:

Carbon, hydrogen, oxygen, nitrogen

COMPOUND TTYPE:

Ester (organic)

STATE:

Liquid

MOLECULAR WEIGHT:

111.10 g/mol

MELTING POINT:

−22°C (−7.6°F)

BOILING POINT:

47°C (120°F)

SOLUBILITY:

Reacts with water; soluble in acetone, toluene, methylene chloride, and some other organic solvents

Cyanoacrylate was discovered in 1942 by American researchers Harry Coover (1919–) and Fred Joiner, employees of the Eastman Kodak Laboratories, in Rochester, New York. Coover and Joiner were attempting to synthesize a clear plastic material that could be used for gun sights. Instead, they obtained a liquid with a tendency to stick tightly to anything with which it came into contact. They decided that the product-then known as Eastman 910—was more of a problem than an asset and set it aside for six years before deciding to explore its adhesive properties.

At that point, Eastman Kodak began studying the possibilities of using cyanoacrylate for military applications, specifically for sealing wounds. It applied to the U.S. Food and Drug Administration (FDA) for permission to market the product for this use, an application that was approved in 1964. Shortly thereafter, military physicians tested cyanoacrylate glues in Vietnam and found them highly effective in sealing the wounds of soldiers. In a spray form, the glue stopped bleeding from chest wounds long enough to allow wounded soldiers to reach a hospital. Although the use of cyanoacrylates by the military proved to be a success, the FDA declined to approve the product for civilian use. The product had a tendency to irritate the skin when it reacted with moisture on the skin, releasing formaldehyde and cyanoacetate, both toxic substances. Eventually, research showed that the octyl ester, 2-octyl-cyanoacrylate, proved to form stronger bonds, was more flexible, and was less irritating than the methyl and ethyl esters used in the original Eastman610 formulation. With this change, the FDA approved the use of 2-octyl-cyanoacrylate for use in closing wounds and incisions. In 2001, the FDA extended this approval to include use of the compound as an antibacterial agent.

HOW IT IS MADE

Cyanoacrylates are made by reacting cyanoacrylic acid with an alcohol, such as methanol, ethanol, or 2-octanol, to form the corresponding ester.

COMMON USES AND POTENTIAL HAZARDS

Cyanoacrylates are still used in a variety of medical applications to close wounds and to protect wounds from infection. The 2-octyl ester is used for this purpose because it has fewer hazardous side effects than do the methyl and ethyl esters. Cyanoacrylate is preferred to stitches for closing wounds because it is less likely to become infected and tends to leave fewer scars. For this reason, the compound is often used for cuts on the face, although it cannot be used in the nose or mouth. Consumers can buy cyanoacrylate products such as BandAid brand Liquid Bandage™ for home use.

Cyanoacrylates are sometimes used in dental procedures. Their ability to bond tightly and quickly, to seal wounds, and to prevent the development of infections make them useful for a number of surgical procedures involving teeth and gums. The primary concern is the selection of esters (such as the 2-octyl ester) that will not cause irritation or infections of the areas being treated.

Cyanoacrylates are also used widely in a number of industrial and household adhesives, perhaps the best known of which is Super Glue™. Manufacturers use cyanoacrylates in the assembly of many products, including trophies, golf clubs and other sports equipment, tools, digital watches, optical lenses, electronic components, lampshades, plastics, scientific instruments, loudspeakers, shoes, jewelry, and videocassettes. Automobile makers use the product to attach trim to cars and trucks. The cyanoacrylates come in a great variety of formulations that make them suitable for bonding with special types of materials (such as ceramics, metals, wood, plastics, and glasses) and under a variety of specialized conditions (such as high or low temperature or very dry or damp conditions).

Cyanoacrylates are also used by forensic scientists to collect fingerprints at crime scenes. The object to be tested is suspended inside a container with at least one transparent side. A few drops of Super Glue or similar cyanoacrylate product is added to the container and the container is sealed and heated to about 100°C (212°F). That heat causes vaporization and polymerization of the cyanoacrylate, resulting in the formation of distinctive white print patterns, a process that make take two hours or more. This cyanoacrylate fuming test has now become the procedure of choice for the detection of latent prints deposited on non-porous objects, such as glass, plastic, rubber, and leather.

Interesting Facts

• The commercial success of cyanoacrylates as glues was assured in 1959 when Harry Coover appeared on the television show I've Got a Secret and used the product to lift host Gary Moore off the floor with a single drop of Eastman Kodak's Super Glue™.
• The polymerization of cyanoacrylates with water begins as soon as the glue is spread on a material, and a strong bond is formed almost immediately. However, polymerization continues for a number of hours and is not complete for 24 to 48 hours, at which point the bonding is considerably stronger than in the first few minutes of application.

Cyanoacrylates bond to skin as quickly and tightly as they do to other materials, so care is required in their use. They are skin and eye irritants, and so should always be used in an area with good ventilation. Exposure to high levels of cyanoacrylate gas can cause severe respiratory problems, and in the most extreme cases can result in death.

Words to Know

ESTER

An organic compound formed in the reaction between an organic acid and an alcohol.

POLYMER

A compound consisting of very large molecules made of one or two small repeated units called monomers.

POLYMERIZATION

The process of creating a polymer; a reaction that causes a polymer to form.

SYNTHESIS

A chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.

FOR FURTHER INFORMATION

"Cyanoacrylates." Impact Adhesives.http://www.impact-adhesives.com/pages/cyano.html (accessed on October 6, 2005).

Davidson, Elaine. "Cyanoacrylates." http://www.repairantiques.com/cyanoacrylates.html (accessed on October 6, 2005).

Fernandez, Tania, and Val Bliskovsky. "Cyanoacrylate Technology: Stay Glued." Pharmabiz.com. >http://www.pharmabiz.com/article/detnews.asp?articleid=13609&sectionid=46(accessed on October 6, 2005).

"Methyl 2-Cyanoacrylate (MCA); Ethyl 2-Cyanoacrylate (ECA)." Occupational Safety and Health Administration. http://www.osha-slc.gov/dts/sltc/methods/organic/org055/org055.html (accessed on October 6, 2005).

"Methyl Cyanoacrylate and Ethyl Cyanoacrylate." International Programme on Chemical Safety. http://www.inchem.org/documents/cicads/cicads/cicad36.htm#9.0 (accessed on October 6, 2005).

Schwade, Nathan D. "Wound Adhesives: 2-Octyl Cyanoacrylate." Medicine: Instant Access to Medicine. http://www.emedicine.com/ent/topic375.htm (accessed on October 6,2005).

See AlsoFormaldehyde