Glue is a substance used for sticking or bonding materials together. Most glues are made from polymers, which are long chains of molecules that have a sticky or adhesive quality.

One common question about glue is why it does not stick to the inside of the bottle. There are several reasons why this may be the case.

1. Surface tension: One reason why glue does not stick to the inside of the bottle is due to surface tension. Surface tension is the measure of the cohesive forces between the molecules at the surface of a liquid. The molecules at the surface of the glue are attracted to each other, causing the glue to form a thin film or layer on the surface of the bottle. This thin film of glue is not able to fully adhere to the bottle, causing it to easily peel off or slide off the surface.
2. Non-porous surface: Another reason why glue may not stick to the inside of the bottle is if the surface is non-porous. Non-porous surfaces, such as glass or plastic, do not have small pores or openings that allow the glue to adhere to the surface. As a result, the glue is not able to fully bond with the bottle and may easily peel off or slide off the surface.