As mentioned previously, some of the new polymers being developed are more complex and, in certain instances, have been found superior to the simple homopolymers. An example of one such polymer is butylene maleic anhydride copolymer which is depicted below.

This copolymer contains areas of both high and low charge density and is able to provide both crystal distortion and dispersancy. Iv is theorized that the methyl groups present impart a slightly positive charge and, consequently, the charge density at the associated maleic anhydride group is more intense allowing for better crystal distortion.

This copolymer is effective in inhibiting calcium carbonate and calcium sulfate scales. It has also proven to be fairly effective for inhibiting calcium phosphate and iron phosphate sludges and functions well as a dispersant for iron oxide