The chemical used to develop PCBs is NaOH. It doesn't need to be a strong solution, 0.6% will do.
The substance used to coat the board before exposure to UV is known as a photresist. Many different chemicals are used, each having different properties, see Wikipedia for more information.http://en.wikipedia.org/wiki/Photoresist
Using the sun to expose PCBs isn't very reliable. It's much better to use a popper light box which is easy to make yourself.
Here's another site with more information on DIY PCBs.
I mostly use the toner transfer process myself and when I do use the photo process I buy pre-sensitised copper clad board.