Why does glue stick? Or Sue against Glue
After staring at the ugly wallpaper in our all-purpose study/computer room for too long to admit, I decided it had to come down. The stuff, however, was stuck and I mean stuck.
It became Sue against Glue. Clearly, I needed an ally.
What kept this ugly crap on the wall, when a Band-Aid on one of the boys’ knees stayed in place for about thirty seconds? This has actually taxed greater minds than mine. There is no simple answer, just like there is not one type of glue. Super glue, wood glue, school glue, the glue on sticky notes, I could probably come up with two-dozen more.
This is actually a science question. (Aren’t they all?)
Forces keep things in place. Cohesive and Adhesive.
| COHESIVE | Property between like molecules to stick because of mutual attraction |
| ADHESIVE | Property between different types of molecules or surfaces to cling together |
Water has both! Cohesion causes drops to form. Adhesion caused the drops to cling to other surfaces.
Water was the key.
Scientists copied geckos too, and put, for example, microscopic glue bubbles inside the adhesive of a sticky note.
So, now we have millions of glue molecules sticking to millions of wall molecules AND wallpaper molecules. (They don’t care if the wallpaper is ugly)
When you open that brand new bottle of glue, and the fancy chains of glue polymers come in contact with water in the air, on the wall and wallpaper– or in my case, the water on my fingers– and the cohesion and adhesion get to work.Well, I’ve had about enough of adhesion and cohesion for one day, at least enough for a blog post.
How do I beat it? The same way that Band-Aids come off knees. I came back to water. Water is a brilliant beautiful molecule. Lots of organic molecules are soluble in water, meaning they form new bonds with the water itself. The oxygen in water is nucleophilic so it attacks other elements. Water breaks bonds.
I’ll confuse the glue by flooding it with water molecules. The higher the temperature of water, the more soluble the molecules are. (It’s a proven fact that heat breaks bonds more readily) Weaken the chemical bonds and the Van der Waals attractions with lots and lots of water.
My hero water will get into the wallpaper and push itself between those molecules.
Guess what? It worked! (Hideous, water soaked wallpaper)
Finished! Thank you water!
2 thoughts on “Why Does Glue Stick?”
Great blog post, Sue. You obviously know your science and thanks for the tip about removing wallpaper, I’m looking forward to reading more of your posts.
Thanks, Amy!