Kirk, actually we don't know how the PVA (in this case) is derivatized, crosslinked or not. The Kuraray site states that it has silanol groups. therefore, these are probably more or less Si-OH groups which can interact with glass surface by hydrogen bonding SiOH......HOSi and of course within the polymer itself
I have first-hand experience with silylating (mostly trimethylsilylating to be precise) agents, since we use them in our lab for GC work. They are really useful stuff (greatly extend the volatility range of coumpounds), but yes, they are really nasty to work with.