Eli5: What makes things “sticky” like tape or any kind of adhesive? How do they stick on to smooth surfaces instead of coming off?
In: Chemistry
In science terms, “sticky” is called adhesion. Imagine how water sticks to the surface of glass. The same principle is used in tape and other such sticky things.
Then, we also need to take a look at smooth surfaces. Let’s take glass for example. If you feel it, it doesnt seem like there are any cracks or crevices, which, for the most part is true. If you look really closely, like through a microscope, you can sometimes find little cracks and crevices, but that’s not too important for the concept of tape sticking to it.
The sticky part of the tape wraps itsself over the surface of the glass as best as it can, and since the adhesion helps it stick, the more that its touching, the stronger it sticks to the surface. You can actually test this, if you take a piece of glass and put a little flour on it to get between the glass and the tape it hardly sticks at all. Or if you get some tape and put it on the thin side of a piece of paper, it hardly sticks at all. This is because all the sticky parts of the tape not only stick to the surface, but they also stick to eachother, which is called “cohesion”
Cohesion is actually a lot stronger than adhesion, so if you take water on glass as an example, its pretty easy to shake a drop of water off the glass, but try to make the water drop split in two. It’s possible, but it’s a lot harder. The same applies to tape, it’s usually a lot easier to take tape off of something than it is to take the sticky stuff off of the tape.
So the adhesion sticks to the surface, and the cohesion makes it so that when you try to take it off, all the sticky stuff works together to prevent it from falling off.
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