Abstract2‐Bromoethoxyphenoxyphosphoryl methacrylate (5) was synthesized by the reaction of 2‐bromoethyl phenylchlorophosphonate (3) with silver methacrylate and then polymerized by a radical initiator. The resulting polymer was soluble in DMF, but insoluble in other organic solvents. The hydrolysis of the polymer with sulfuric acid led to the corresponding poly(methacrylic acid) with a molecular weight ofMn=4,4·105(Pn=5,1·103).5was copolymerized with acrylonitrile and the monomer reactivity ratio was determined:r1= 2,20,r2