Styrofoam is a polymer. Polymers are large molecules made of units of chemicals, called monomers, linked together, much like links in a chain.
Styrofoam is a brand name of Dow Chemical. Styrofoam is used to make products, such as disposable coffee cups, packing peanuts, and coolers.
Styrofoam was originally discovered by Geog Munters, a Swedish inventor. But in 1941, led by Ray McIntire and a team of researchers in Dow’s Chemical Physics Lab, McIntire, using Munters’ method, made foamed polystyrene. With exclusive rights to use Munters’ patents, Dow mass produced styrofoam.
Foamed polystyrene crunches when cut, breaks into what looks like tiny sponge balls, and is moderately soluble in some organic solvents, such as the solvents in spray paint. Actually, saying that polystyrene dissolves in acetone, much like sugar dissolves in water is incorrect. Instead, acetone causes the bonds (links) between the styrene monomers to break. When the bonds break, it opens air filled cells in the foam and the previously trapped air escapes. Styrofoam is about 90% air that is trapped in closed cells with polystyrene walls. The pressure of the air inside the cells, like air in a balloon, keep the walls rigid. Without the air, the walls collapse and thus the polystyrene has lost its foamed volume.
Discover for yourself
1. How to Produce Foam
- In a glass half- filled with tap water, add about 4 drops of liquid dish detergent.
- Using a drinking straw, blow air into the water until foamy soap bubbles fill the glass.
Results: The bubbles that form have a thin soap and water membrane filled with air. Styrofoam is made by bubbling gases into liquid polystyrene. Cells of polystyrene are filled with these gases. The foaming gases are replaced with air and voila’! Styrofoam is produced.
2. Model the effect of breaking Styrofoam cells
- Using a toothpick, pop the soap bubbles in the soapy foam from step 1.
Results: As the bubbles are broken air escapes and the soap-water membrane surrounding each soapy bubble collapses. Without the air, the unfilled soapy film takes up less space and in time dissolves in the water. Styrofoam is not soluble in many solvents. But it affected by acetone, an organic solvent used in some fingernail polish remover. See the following to discover how acetone breaks the air filled cells of Styrofoam.
3. How do break Styrofoam cells
- In a well ventilated area, outside is best, pour about 1/4 cup (63 mL) of acetone in a glass or ceramic bowl.
- Stand a Styrofoam cup in the bowl of acetone. Watch —the Styrofoam cup seems to melt into the acetone. Continue to add Styrofoam materials, peanuts, packing, etc…
Results: The Styrofoam is not dissolving into the acetone. Instead, the bond holding the monomers together are breaking allowing the trapped air to escape. Since about 90% of Styrofoam is air, there is an extreme reduction in the volume of the material when the air is released leaving only polystyrene.
It is not safe to be in a closed room with acetone because it evaporates so quickly. Thus, outdoors, allows the acetone to safely evaporate. Left in the bowl will be solid polystyrene.
The following video demonstrates what happens to Styrofoam in Acetone. Note, the Styrofoam is not dissolving in the Acetone.
The second video is an idea for a science fair project.
Science Project Idea.