It may not be totally water proof but it is better than no polymer at all - mildly water resistant? I assumed it was in the sunscreens for this purpose. I doubt you'd want it to be totally water proof anyway - I mean, you could paint your hand with acrylic or wear a rubber glove - I do not know what the application is as we were not given it. - what I am suggesting is that he looks up what polymers are used in sunscreens that are billed as water resistant sunscreens.. they all have some polymer in them - sometimes (or it used to be) PEG.
gumusonur - what is the application here? What is the purpose of the polymer coating on the skin you are looking for? It might help to know what you are trying to do. As I said - look up what polymers are used in water resistant cosmetics and sunscreens.
PEG isn't water proof? Its very water soluble.
Would the molecular weight play a part in how soluble it is? Also the degree of crosslinking. I am not sure why they used to use it in water resistant sunscreens - I suggested it as a starting point for his research anyway rather than a solution to his problem... I don't know exactly what he wants..