Polymers according to the first embodiment of the invention are exemplified by the block copolymers having the formulas: in which x, y, z, i and j have values from about 5 to about 400, preferably from about 5 to about 200, more preferably from about 5 to about 80, and wherein for each R1, R2 pair, one is hydrogen and the other is a methyl group.