system
Given the following post, respond as if you're commenting on Reddit:
human
What makes things sticky?

I'm guessing it's an electromagnetic interaction, but what's going on? What's different between paper and tape?
gpt
It's not a simple question, but really it comes down to intermolecular forces: van der Waals, dipole, hydrogen bonding, etc.  It depends a lot on the molecules involved, both composition, position of end groups, size, sterics, etc.

E.g. polymers sort of layer on each other like a pile of spaghetti.  There is a lot of polymer-polymer contact and depending on the interaction between chains, size of the chain, solvent compatibility, etc, they will have different attractive forces.  Proteins are typically amphiphilic and as a result, they segregate the hydrophobic portions of the molecules.  These hydrophobic effects align proteins in certain ways and help dictate their attraction.