We could watch acetone devour styrofoam all. Day. Long.
Although, technically speaking, the acetone isn’t devouring anything. Styrofoam is made of up countless interconnected styrene molecules that together make up a material known as polystyrene.
In the mid-20th Century, Dow Chemicals came up with a process that turns small, spherical polystyrene beads into a closed-cell foam structure that takes up way more space than the starting material. This end product is 98% air, but is still just a bunch of styrene molecules, linked together.
What the acetone does is weaken the interactions between the styrofoam’s long polystyrene chains, releasing trapped air in the process. The result is a thick, gloopy mass of polystyrene in a pool of acetone. If you allow the acetone to evaporate, you wind up with a firm mass of polystyrene resin that is much less voluminous (and, as a result, much more dense) than the original styrofoam.
NB: This sytrofoam/acetone gloop is highly flammable, and is similar to napalm. If you try this at home, you want to be very, very careful.
