Patent ID: 8158561

Claim:
A method for inhibiting corrosion of metal in contact with an aqueous system and/or inhibiting scale formation in the aqueous system, said method comprising adding to the aqueous system an effective amount of a polymer composition comprising polymerized units derived from: a) 1% to 100%, by weight, of a phosphorus-containing amide monomer having the general formula; wherein X 1 , X 2 are each, individually, hydrogen, linear or branched C 1 -C 4 alkyl groups, aryl groups, nitrogen-containing groups, or metal ions; X 1 and X 2 together may be a multivalent metal atom, or X 1 and X 2 may be linked together to form a cyclic structure; R 1 , R 2 , R 3 , R 4 are each, individually, hydrogen, linear or branched C 1 -C 4 alkyl groups, aryl groups, and combinations thereof; and R 5 is absent, or R 5 is linear or branched C 1 -C 20 alkyl groups, aryl groups, ethylene oxide residue, propylene oxide reside, or combinations thereof; or R 5 is —R 6 —O—, where R 6 is either absent or, when it is present, it is linear or branched C 1 -C 20 alkyl groups, aryl groups, ethylene oxide residue, propylene oxide reside, or combinations thereof; wherein the weight percent is based on the total weight of said polymer composition and the weight percents of all components totals 100%, and wherein said polymer composition has a weight average molecular weight of between 1,000 and 200,000 grams/mole, and wherein the aqueous system has a temperature up to 250° C., a pressure up to 68.9 MPa, or both.