Recently bought a tube of super glue to fix something, and I started wondering how it stays a liquid inside of the tube/bottle and doesn’t just stick to the sides?
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SuperGlue is a name brand of [CyanoAcrylate (CA) glue](https://en.wikipedia.org/wiki/Cyanoacrylate). It’s basically a bunch of chain links floating as a liquid, but as soon as they touch certain chemicals (usually water) the chain links combine into long chains that hold together.
So they don’t ‘dry’ or ‘stick’ inside the tube because they don’t have the specific trigger to turn into long chains. It’s not until they touch water (such as humidity) that they cure into a hard, stuck together plastic.
Superglue hardens by reacting with the air. When you put the cap back on air doesn’t get in the tube and so it doesn’t harden.
If you don’t close the cap fully then the entire tube goes solid (in reality the cap will never quite be perfect so this will happen eventually anyway).
Oxygen in the bottle inhibits the polymerization of the glue. While water, in the form of moisture in the air, (especially as it settles on surfaces) activates it.
Super glue is activated by exposure to oxygen. If the glue is kept in an airtight container with no oxygen, it will generally remain fluid. This is why after opening, the super glue tends to form a block at the tip of the dispenser because oxygen gets in. Since most (cheap) containers are not completely air tight, after awhile an opened super glue dispenser will also become solid.
The bottle keeps the glue from reacting with the moisture in the air. If you’re asking specifically about the bottle, the plastic bottles used aren’t reactive so it doesn’t interact with the glue.
Others have answered your first question but as to your second, glue tubes are usually made from (or lined with) a plastic such as polyethylene, and polyethylene is extremely hard to glue.
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