Fluoroalkyl end-capped cooligomers, containing polydimethylsiloxane and polyoxyethylene segments were prepared under very mild conditions by the cooligomerizations of fluoroalkanoyl peroxides with methacrylate monomers containing the corresponding segments and comonomers such as dimethylacrylamide and acryloylmorphotine. These obtained fluorinated cooligomers exhibited amphipathic characteristics and became soluble in water and common organic solvents. In particular interest, fluoroalkyl end-capped cooligomers containing polyoxyethylene units were soluble not only in poly(methylphenylsiloxane) (silicone oil) but also in water, including common organic solvents except for hexane. Additionally, these fluorinated cooligomers were able to reduce the surface tension of water and m-xylene quite effectively, to around 15 and 20 mN/rn levels, respectively. In these fluorinated cooligomers, fluoroalkyl end-capped acryloylmorpholine cooligorners containing polyoxyethylene segments were applicable as a novel emulsifying agent against water and silicone oil. (c) 2005 Wiley Periodicals, Inc.