Cyanoacrylate
The original patent for cyanoacrylate was filed in 1947 by the B.F. Goodrich Company[2] as an outgrowth of a search for materials suitable for clear plastic gun sights for the war effort.
[3] The team quickly rejected the substance for the wartime application, but in 1951, while working as researchers for Eastman Kodak, Coover and a colleague, Fred Joyner, rediscovered cyanoacrylates.
National Starch and Chemical Company purchased Eastman Kodak's cyanoacrylate business and combined it with several acquisitions made throughout the 1970s forming Permabond.
Other manufacturers of cyanoacrylate include LePage (a Canadian company acquired by Henkel in 1996), the Permabond Division of National Starch and Chemical, which was a subsidiary of Unilever.
To facilitate easy handling, a cyanoacrylate monomer is frequently formulated with an ingredient such as fumed silica to make it more viscous or gel-like.
In general, the C=C groups rapidly undergo chain-growth polymerisation 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 normal levels of humidity in the air causes a thin skin to start to form within seconds, which very greatly slows the reaction; hence, cyanoacrylates are applied as thin coats to ensure that the reaction proceeds rapidly for bonding.
Cyanoacrylate adhesives generally have a short shelf life—about one year from manufacture if unopened, and one month once opened, but this can be extended by refrigeration.
Common examples include mounting a workpiece to a sacrificial glue block on a lathe, and tightening pins and bolts.
Cyanoacrylate-based glue has a weak bond with smooth surfaces and as such easily gives to friction; a good example of this is the fact that cyanoacrylates may be removed from human skin by means of abrasives (e.g. sugar or sandpaper).
In the US, due to its potential to irritate the skin, the U.S. Food and Drug Administration (FDA) did not approve its use as a medical adhesive until 1998 with Dermabond (2-octyl cyanoacrylate).
[8] A 1986 independent study suggests that cyanoacrylate can be safer and more functional for wound closure than traditional suturing (stitches).
[10][11] Similarly, stringed-instrument players can form protective finger caps (typically, when they lose their calluses due to inactivity or accidents) with cyanoacrylates.
[18] Cyanoacrylates are used to assemble prototype electronics (used in wire wrap), flying model aircraft, and as retention dressings for nuts and bolts.
[19] Cyanoacrylate glue's ability to resist water has made it popular with marine aquarium hobbyists for fragmenting corals.
However, as a class of adhesives, traditional cyanoacrylates are classified as having "weak" resistance to both moisture and heat[20] although the inclusion of phthalic anhydride reportedly counteracts both of these characteristics.
[21] Cyanoacrylate glue is also used frequently in aquascaping both freshwater and marine aquariums for the purpose of securing the rhizomes of live plants to pieces of wood or stone.
Some hobby applications call for cyanoacrylate glue mixed with inorganic fillers such as baking soda (sodium bicarbonate)[23] and calcium oxide.
[25] Such tubes often have a long, thin metal nozzle for improved precision in applying the glue to the base of the fletching and to ensure secure bonding to the arrow shaft.
[32] The compound 2-octyl cyanoacrylate degrades much more slowly due to its longer organic backbone (series of covalently bonded carbon molecules) and the adhesive does not reach the threshold of tissue toxicity.
[35] Acetone, commonly found as a fraction of nail polish remover (or at hardware stores in pure form), is a widely available solvent capable of softening cured cyanoacrylate.
Cyanoacrylates are moisture-sensitive, and moving from a cool to a hot location will create condensation; after removing from the refrigerator, it is best to let the adhesive reach room temperature before opening.
