Cyanoacrylate
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Cyanoacrylate is the generic name for substances such as methyl-2-cyanoacrylate, which is typically sold under trademarks like Superglue and Krazy Glue, and 2-octyl cyanoacrylate, which is used in medical glues such as Dermabond and Traumaseal. Cyanoacrylate adhesives are sometimes known as "instant adhesives". The acronym "CA" is quite commonly used for industrial grades.
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History
Cyanoacrylate was discovered during World War II when searching for a way to make synthetic gun-sights (a substitute for spider silk). It did not solve this problem, since it stuck to all the apparatus used to handle it. Later it was developed into a more useful form by the Eastman Kodak company in 1958. The term is now used to refer to a range of adhesives based on similar chemistry.
Medicine
The use of cyanoacrylate glues in medicine was considered fairly early on. Eastman Kodak and Ethicon began studying whether the glues could be used to hold human tissue together after surgery. In 1964, Eastman submitted an application to use cyanoacrylate glues to seal wounds to the United States Food and Drug Administration (FDA). Soon afterward Dr. Harry Coover's glue did find use in Vietnam--reportedly in 1966, cyanoacrylates were tested on-site by a specially trained surgical team, with impressive results. In an interview with Dr. Coover by the Kingsport Times-News, Coover said that the compound demonstrated an excellent capacity to stop bleeding, and during the Vietnam War, he developed disposal cyanoacrylate sprays for use in the battlefield.
"If somebody had a chest wound or open wound that was bleeding, the biggest problem they had was stopping the bleeding so they could get the patient back to the hospital. And the consequence was--many of them bled to death. So the medics used the spray, stopped the bleeding, and were able to get the wounded back to the base hospital. And many, many lives were saved," Coover said.
Properties
In its liquid form, cyanoacrylate consists of monomers of cyanoacrylate molecules. Methyl-2-cyanoacrylate (CH2=C(CN)COOCH3 or C5H5NO2) has a molecular weight equal to 111.1, a flashpoint of 79 ºC, and 1.1 times the density of water. Ethyl-2-cyanoacrylate (C6H7NO2) has a molecular weight equal to 125 and a flashpoint of 75 °C.
Generally, cyanoacrylate is an acrylic resin which rapidly polymerises in the presence of water (specifically hydroxide ions), forming long, strong chains, joining the bonded surfaces together. Because the presence of moisture causes the glue to set, exposure to moisture in the air can cause a tube or bottle of glue to become unusable over time. To prevent an opened container of glue from setting before use, it must be stored in an airtight jar or bottle with a package of silica gel.
Another important trait is that cyanoacrylate sets fast, often in less than a minute. A normal bond reaches full strength in two hours, and is waterproof. There are also accelerants that can force cyanoacrylate to set in two or three seconds, at some loss of strength.
Acetone, which is sometimes found in nail polish remover, is a commonly available solvent capable of softening cured cyanoacrylate.
Cold temperatures cause cyanoacrylate to become brittle. Cyanoacrylate's bond can be weakened, allowing disassembly, by placing a glued object in a household freezer for several hours.
If applied to cotton, cyanoacrylate undergoes an exothermic reaction rapid enough to cause minor burns if spilled on clothing.
Uses
Cyanoacrylate is a tenacious adhesive, particularly when used to bond non-porous materials or those that contain minute traces of water. As such it is very good at bonding body tissue, and while this can be a bothersome (or even dangerous) side effect during everyday use, it has been exploited for the benefit of suture-less surgery.
Cyanoacrylates are often used to assemble prototype electronics (see wire wrap), flying model aircraft, and as retention dressings for nuts and bolts. Their effectiveness in bonding metal and general versatility have also made them popular amongst modeling and miniatures hobbyists.
One non-adhesive use for cyanoacrylate is as a forensic tool. Fumes from (warmed) CA can develop latent fingerprints on surfaces. The invisible fingerprint residues react with the CA fumes and atmospheric moisture to become visible and can then be recorded. This technique was shown in the films Beverly Hills Cop II, National Treasure, and frequently features in the television series CSI: Crime Scene Investigation and its spin-offs.
External links
- Super Glue Official Website
- Was Super Glue invented to seal battle wounds in Vietnam? (from The Straight Dope)
