Eight novel polyfluorinated surfactants (CnF2n+1CONH(CH2)(2) N+(CH3)(2)C16H33 Br-; abbreviated as CnF-S, where n = 1, 2, 3, 4, 5, 6, 8, 10) were synthesized and their intercalation into cation-exchangeable clay was investigated. All of the polyfluorinated surfactants intercalated in amounts exceeding the cation exchange capacity (CEC) of the clay. The C4F-S and C5F-S surfactants exhibited intercalation up to 480% of the CEC as a saturated adsorption limit. On the basis of X-ray analysis, CnF-S surfactants intercalated between clay nanosheets to form a bilayer structure in which the surfactant molecules tilt at an angle of similar to 60 degrees with respect to the day surface. The saturated adsorption limits and layer distances differed between surfactants with short (n = 1, 2) and long (n = 3-10) perfluoroalkyl chains. For long-chain surfactants, their saturated adsorption limits were independent of the perfluoroalkyl chain length and the layer distances systematically increased with increasing perfluoroalkyl chain length. These results suggest that the microscopic orientation differed between the short and long chains. X-ray analysis showed that the long-chain surfactants orient the perfluoroalkyl chains at a tilt of 41 +/- 5 degrees with respect to the clay layer. This value was in good agreement with polarized IR measurements of 42 +/- 2 degrees for this angle.