The use of perfluorinated anionic carboxylic acids (PFCAs) as surfactants is common and widespread. Investigations of PFCAs have shown that their physical properties and toxicological aspects are dependent upon the carbon chain length. The magnitude of these properties is not a linear function of chain length and as yet no explanation of these unique observations has been made. Their environmental dissemination is expected to be nonproportional to the PFCAs chain length. An understanding of the fundamental underlying reason for this novel physical property, chain length trend, would aid further investigators' interpretation of their environmental and toxicological observations. In this study we have utilized F-19 NMR techniques, such as, chemical shift, spin-lattice (T-1), and spin-spin (T-2) relaxation phenomena, coupling constants, and variable-temperature NMR to furnish a qualitative explanation of why increasing the carbon chain length causes unexpected intrinsic property changes within this group of chemicals. Results indicate that polyfluorinated chains adopt helical twist geometry unlike their hydrocarbon counterparts which exhibit a zigzag geometry. Variable-temperature F-19 NMR showed that chain rigidity within these molecules is also a function of the fluorocarbon chain length. There is a distinct change in geometry and rigidity of the acid chain between 8 and 10 carbon lengths. These unique geometric changes in this class of compound must be considered when assessing their dissemination in the environment, for example, in the case of environmental modeling.