|MadSci Network: Chemistry|
Before I answer the question, let me say that there are several answers posted on MadSci that answer the question concerning the ingredients of nail polish and nail polish remover ( What are the ingredients in fingernail polish? What chemicals affect nail polish durability?, fingernail polish science fair, and What chemical in nail polish causes it to dry fast?). I will repeat some of what I learned from those questions/answers here. The three main types of ingredients in nail polish are (1) organic solvents and drying agents, (2) thickeners and hardening agents, typically polymeric species such as polyester-urethanes resins or styrene/acrylic copolymers, and (3) coloring and other agents to provide certain colors and effects such as shine.
Now to answer the question you asked concerning the chemicals and chemical reactions that make nail polish removal possible. Here's the beuaty of the entire thing- there is no chemical reaction. The nail polish remover is just the organic solvent that is used as an ingredient in the nail polish. That is, ingredient #1 above is sold as a "pure" material (meaning that ingredients 2 and 3 are not present, but that does not mean that other chemicals are not present to save costs). The hardened nail polish is dissolved by the nail polish remover (basically putting it back into the form that it was in when applied to a nail). For dissolution to occur, no chemical reaction takes place. However, what is necesary is that the solvent likes the polymer. There is a rule of thumb that may be a bit oversimplified, but it works, and that is "like dissolves like." And in this case, it can really be oversimplified and said that the organic polymer that is the hardened polish on a nail can be dissolved by an organic solvent (by no means an exact rule, but it usually gives one a good starting point). So if a solvent likes the polymer, as is the case for nail polish and nail polish remover, the solvent molecules (which may be ethyl acetate or acetone, two organic solvents) get in between the polymer chains and "push" them apart. There are so many of the solvent molecules pushing the polymer chains apart that eventually the polymer chains do not know that other polymer chains exist and you get a solution. This solution can then be wiped off with a cotton ball or tissue when nail polish is dissolved by nail polish remover. Next time you remove nail polish (or see someone remove nail polish), look at the cotton ball or tissue, eventually the solvent will evaporate (similar to the drying process as to when one is painting their nails) and leave a hardened residue on the cotton ball. This dissolving/evaporating process is endless (for the most part) so that if you can collect the dissolved nail polish, you could use it over and over as long as you have a solvent.
I hope this answers your question! Now can you think of why one blow's their nails to aid in the drying process. Now this is a question of evaporation!
Try the links in the MadSci Library for more information on Chemistry.