Why do polymers make solutions viscous?
For one, polymers move very slowly, or at least, they move a lot more slowly than do small molecules. It makes sense that the faster molecules in a liquid move, the more easily the liquid will flow. So when we dissolve a polymer in a solvent, their slow motion makes the whole solution more viscous. Ok, polymers are slow. But why does the whole solution become viscous? Do polymers make the solvent molecules move more slowly, too? How? The answer is yes. Polymers are rather pushy. It’s not enough for them to move slowly themselves, but they feel they must make the solvent molecules move more slowly, too. So how and why do the polymers go about imposing their ways on the otherwise free-spirited solvent molecules? To understand, it helps to think about a fabulous three-day holiday weekend. You’re leaving town for the holiday, going on a road trip with a few of your favorite co-conspirators. You pile into your sleek, fast convertible and hit the highway, in search of adventure. But soon aft
