Syntheses were performed of copolymers of acrylic acid and trimethylvinylsilane with a fluoroalkyl group on both terminals (fluorinated silicon oligomers with carboxylic acid groups; R-F-(CH2CHCOOH)(x)-(CH2CHSiMe2)(y)-R-F; R-F = C3F7, C2F5(CF2OCFCF3), C2F5(CF2OCFCF3)(2)). Surface tension and static Light scattering measurements were conducted to investigate the solution properties of the oligomers synthesized, and the effects were examined of R-F, the CH2CH(COOH) segment, and the copolymerization ratio of the oligomers on their solution properties. These fluorinated silicon oligomers were found to have an excellent ability to lower the surface tension of water (the lowest surface tension attained : 17.4 [mN/m]) and form molecular assemblies of a colloidal dimension that is larger in size than ordinary surfactant micelles above a certain concentration. Introduction of R-F into the silicon oligomers or increase in the chain length of the introduced R-F reduced the concentration at which molecular assemblies were formed. Increase in the number of CH2CH(COOH) segments had no effect on the surface tension lowering ability while it caused a rise in the concentration of molecular assembly formation. Moreover, an increase in the number ratio of CH2CH(COOH) segments to CH2CH(SiMe3)) segments was found to diminish the surface tension lowering ability and reduce the concentration at which formation of molecular assemblies started.