What gives certain objects that property of being sticky? How is stickiness transferred?
Please emphasize the “eli5”, I missed all of the crucial years of school Gr 4-10
In: Biology
Things are sticky because they attach to you. Imagine billions of tiny hands on the surface, if anything comes near, it grabs it. Each one doesn’t hold on very hard, but there are billions. So you have to put in energy to tear apart the bonds.
Things transfer stickiness when you pull, and the connection of the sticky material to itself is weaker than its connection to you. So you end up with the material on you.
Stickiness is adhesion caused by a combination of two things, both of which must be present for us to perceive something as “sticky”:
1. The material needs to naturally spread and wet the surface you’re putting it in contact with. Think oil on clean glass (vs. water on a freshly waxed car). This is controlled by the surface energy of the 2 materials.
2. The material must dissipate energy when you try to pull it off the surface, usually through viscous flow. Think taffy or silly putty (vs. water or a piece of steel).
Source: spent 12 years designing adhesives.
Even if a surface appears to be flat to our eyes, it’s usually quite rough on a microscopic level. If we put two such surfaces together, only the tips of the rough bits actually touch, and the rest of the void is filled with air. Sticky things are solid enough not to flow away, but gooey enough to get into the little nooks and crannies of a surface. When materials are in such intimate contact, forces between close-by atoms make them attract each other.
There are some more nuances, but this is the gist of it.
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