Abstract: A method that Isopropenyl phosponic acid ( IPPA) monomer is synthesized by acetone (AC), phosphorus trichloride (PT) and glacial acetic acid has been introduced. Then AA-IPPA copolymer has been synthesized by isopropenyl phosphonic acid and acrylic acid (AA). The influence of synthetic conditions on the performance of the copolymer has been discussed.Based on the characteristics of molecular structure and reaction mechanism of thinner as drilling fluids, AA-IPPA can be used as mud thinner. Laboratory experiment results show that the thinner possesses excellent thinning property and good temperature resistance, and the ability of salt and calcium resistance is
better than polymer of acrylic acid.

Key words: isopropenyl phosphonic acid, copolymer, synthesis, mud thinner