[Atomic-S (OP)]

what is the chemical basis of the setting of cyanoacrylate superglue? This is of interest for finding the optimum storage method because it seems to  have a short shelf life

[Bored chemist]

If I remember rightly it's an anionic chain reaction.
It keeps better in the fridge than at room temp.

[CliffordK]

One can now buy mini single-use superglue tubes.  Perhaps not the most efficient packaging, but the unopened tubes will keep better than the opened ones.

[Atomic-S (OP)]

Does exposure to oxygen have anything to do with it?

[CliffordK]

According to notes, it is the moisture that causes the superglue to harden.

http://www.waynesthisandthat.com/spuerglue2.htm

I'm not sure the effect of air.  The note above suggests the presence of an alcohol, but it doesn't seem to be listed in the ingredients.  There is often a small amount of Hydroquinone which seems to be a very low volatility alcohol.

I'm not quite sure what causes the odor???  Anybody know?

Anyway, moisture in the air will react with superglue.

Does it spontaneously polymerize without moisture?

[Bored chemist]

I'm not convinced that that website knows what it's talking about. Superglue is pretty nearly pure ethyl cyanoacrylate.

Hydroquinone is used as an inhibitor of free radical reactions.
And the odour of the stuff is just the way it smells. Lots of esters have distinct aromas.

Also, it's not moisture that cause it to set it's anything slightly alkaline.
http://www.chm.bris.ac.uk/motm/superglue/superglueh.htm

[evan_au]

A clarification: Apparently the OH^- in water can trigger the polymerisation (but then the residual H⁺ should stop it?).

From http://en.wikipedia.org/wiki/Cyanoacrylate#Properties

In general, cyanoacrylate is an acrylic resin that 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 tactic is attaching a hypodermic needle on the opening of glue. After applying, residual glue soon clogs the needle, keeping moisture out. The clog is removed by heating the needle (e.g., by a lighter) before use