Ask A Scientist© Chemistry Archive

name        Jason
status      student
age         13

Question -  What makes gum stick to things?
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There are four things that make gum (and other adhesives) stick.
1. The gum/adhesive has a low surface tension so that it "wets" the surface.
2. Weak boundary layers, such as saliva, attaching the gum to the substrate
have been removed. It is the presence of saliva in the mouth (weak boundary
layer) that keeps gum from sticking to your teeth.
3. The gum is soft, so that it penetrates the nooks and crannies of the
substrate providing a better mechanical bond to the substrate.
4. The gum has a very high molecular weight so that the intertwined chains
of the gum polymer stay entangled when the gum is stretched.

Vince Calder
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