Five samples of perfluoroheptyl end capped polyacrylic acid ( F P A A) having ahigh surface activity were prepared by free radicalpolymerization ofacrylicacid . Theinitiatorwas perfluorooctanoyl peroxide which produced the free radicalof heptyl at 45 ℃. The yieldsof F P A A were in the range of 10 % to 25 % . The weight average molecular weights were2 62 ×104 to 7 99 ×104 and the polydispersity indexes were 1 97 to 5 64 ,depending on theconcentration of the initiator in the monomer. The surface tension was about 15m N/m at30 ℃forthe aqueous solution of F P A Awith the weight average molecular weight2 62 ×104in the concentration of about 0 01g/ m L. The molecular areas of F P A A at the air waterinterface under the condition ofcritical micelle concentration were 3 2 to 4 6n m2 ,which areobviously larger than the area per molecule of perfluorooctanoic acid (2 14nm 2) and muchsmaller than that of ordinary polyacrylic acid (83 4nm 2) . It means that the polymermoleculesin the surface adsorbed layer form the brush structure because of the special effectof the perfluoroalkyl groups at the chain ends . Five samples of perfluoroheptyl end capped polyacrylic acid (FPAA) having ahigh surface activity were prepared by free radical polymerization of acrylic acid. Theinitiator was perfluorooctanoyl peroxide produced the free radical of heptyl at 45 ° C. The yieldof FPAA were in the range of 10% to 25%. The weight average molecular weights were2 62 × 104 to 7 99 × 104 and the polydispersity indexes were 1 97 to 5 64, depending on the concentration of the initiator in the monomer. The surface tension was about 15 mN / m at 30 ° C forthe aqueous solution of FPA Awith the weight average molecular weight2 62 × 104 in the concentration of about 0 01g / m L. The molecular areas of FPAA at the air water interface under the condition of critical micelle concentration were 3 2 to 4 6n m2, which areobviously larger than the area per molecule of perfluorooctanoic acid (2 14nm 2) and muchsmaller than that of ordinary polyacrylic acid (83 4nm 2). It means that the polymermole culesin the surface adsorbed layer form the brush structure because of the special effect of the perfluoroalkyl groups at the chain ends.