The idea of having a material that is fluorinated on the top, but not fluorinated on the bottom, the side that has to stick to the pan, is a good one. Carbon-fluorine bonds are too strong. This can be done by simply blowing F 2 gas over the surface of the polyethylene. Although you might not want to use toxic fluorine gas to make a cooking pan, this method is used to give polyethylene tubing a PTFE coating on the inside. As for roughening the surface to increase contact area, that might be a good idea, if the metal in the pan and PTFE liked each other.
Adhesive forces are proportional to the amount of surface area in contact.
However, repulsive forces are also proportional to the amount of surface area in contact. If we roughen the surface, we increase the surface area, and therefore we also increase the repulsive force between the PTFE and the frying pan. Maybe some protein like albumin or casein can make PTFE stick to something. Using holes to bolt the PTFE down with another material isn't a bad idea, as far as I can tell. As for using proteins to glue PTFE, they probably couldn't handle the temperatures that are found right on the surface of the frying pan.