In a previous article, it was shown that 1H,1H,7Hperfluoroheptyl iodide (6:1 FTI-7H) has a relatively high affinity for water compared to 6:1 FTI. The electron-withdrawing F atoms were thought to make the H atom at the terminal methyl group of 6:1 FTI-7H significantly H-bond donating. In fact, A of 6:1 FTI-7H is positive (0.24) and higher than that of 6:1 FTI (0.13). However, incomplete fluorination affects not only A but also S and L values. The S and L values of 6:1 FTI-7H are 0.36 and 0.50 higher, respectively, than those of 6:1 FTI, although the size (V) of the two compounds is similar. A term-by-term analysis of the PP-LFER model indicates that the higher S of 6:1 FTI-7H than 6:1 FTI contributes more to the lower Kaw and KHxd/w values of 6:1 FTI-7H. Similarly, 1,8-DHPFO has A, S, and L values that are 0.24, 0.27, and 0.78 higher, respectively, than its perfluorinated counterpart, perfluorooctane. Increased S and L mean that partially hydrogenated PFAS interact more strongly with any phase than the fully fluorinated analogs do. Thus, even one or two H substitutions on the perfluoroalkyl chain make the molecule significantly more interactive, reducing the characteristically weak interaction properties of PFAS.