It looks like this
P(St-MMA-AA)
is simply an abbreviation for this
poly (styrene-methyl methacrylate-acrylic acid)
Here is an article on latex:
http://en.wikipedia.org/wiki/Latex
Styrene, methyl methacrylate and acrylic acid can be looked up on chemfinder:
http://chemfinder.cambridgesoft.com
It looks like the substance you're asking about is a latex made from many, many molecules of those three types. I don't know any more about it than that.