What ingredient inside nail polish causes Styrofoam to dissolve?
Acetone - Some nail polish removers, paint thinners and household cleaning supplies contain an organic solvent known as acetone. Acetone has a high degree of solvency. This simply means that many substances easily dissolve in it.
According to toxtown.nlm.nih.gov, acetone is an organic solvent which is used to dissolve other substances, fats, styrofoam, paint and varnishes.
How does this ingredient inside nail polish make Styrofoam dissolve?
Styrofoam is made from commercially manufactured petroleum refined to form liquid hydrocarbon, polystyrene, which is also used to make plastic bottles. But when carbon dioxide is bubbled through polystyrene it becomes foam-like and is used to make styrofoam. When acetone is added to styrofoam, the air between the styrofoam molecules allows acetone to slide in between the polymer chains of styrofoam and separate them, releasing the air. After the air between the polymer chains of styrofoam is released, the styrofoam softens and becomes a blob of polystyrene.