The present invention pertains to sulfonated substantially random interpolymers made from monomer components comprising from 1 to 65 mole percent of (a) at least one vinyl or vinylidene aromatic monomer, or (b) at least one hindered aliphatic or cycloaliphatic vinylidene monomer, or (c) a combination of at least one vinyl or vinylidene aromatic monomer and at least one hindered aliphatic or cycloaliphatic vinylidene monomer, and from 35 to 99 mole percent of at least one aliphatic α-olefin having from 2 to 20 carbon atoms; and optionally, from 0 to 20 mole percent of a diene containing from 4 to 20 carbon atoms; wherein the sufonated interpolymer contains at least one mer (or moiety) of a group represented by the formula -SO3-M where M is hydrogen or a group 1, 7 or 12 metal in ionic form or combination thereof. The present invention also pertains to blends of these polymers with polyamides and polyolefins. These blends are useful as materials which can be formed into a wide variety of plastic articles which take advantage of the combination of toughness, heat resistance, and solvent resistance. The present invention also pertains to articles prepared from substantially random interpolymers which are surface sulfonated.