Cyanoacrylate
Cyanoacrylate is the generic name for methyl-2-cyanoacrylate, the substance usually sold under the trademarks Superglue and Krazy Glue.
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.
Properties
In its liquid form, cyanoacrylate consists of monomers of cyanoacrylate molecules, (C5H5NO2) CH2=C(CN)COOCH3, and has molecular weight equal to 111.1
Its burning point lies at 79 ºC and its density is 1.1 times the density of common water (H2O).
It is an acrylic resin which rapidly polymerises in the presence of water (specifically hydroxyl ions), forming long, strong chains, joining the bonded surfaces together. During setting, it exudes concentrated acetic acid, making a strong smell of vinegar.
Another important trait is that cyanoacryate sets up 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 a set-up as fast as two or three seconds, at some loss of strength.
Acetone, which is found in nail polish remover, is a commonly available solvent capable of softening cured super glue.
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 effect can be a nuisance (or even dangerous) for everyday use, it has been exploited for the benefit of suture-less surgery. Its major polymerization byproduct, acetic acid, is biocompatible. Cyanoacrylates are used in orthopedic surgery to glue metal appliances to bone. They are often used, for example, to glue artificial hip appliances to femurs and pelvic girdles.
Cyanoacrylates are used in forensic science for fingerprint detection. The liquid glue is vaporised and the vapour passed over the object suspected of having fingerprints. The minute traces of water in the print cause the polymerisation of the vapour, which sets hard, forming a solid version of the print, which is rendered very much more visible and much more robust.
Cyanoacrylates are often used to assemble prototype electronics (see wire wrap), flying model aircraft, and as retention dressings for nuts and bolts.
