Table shows examples of linear QSRR equations for RI prediction. It can be clearly seen that the use of RI_PEG_LM and RI_PEG_DL descriptors improves the accuracy. The improvement of the accuracy is highest for Hex4MPy and Bis2MPyC9 and lowest for Bis4MPyC6. This is consistent with the fact that Bis4MPyC6 is the most polar and the most different from PEG. These MD are the most significant or are among the most significant for all three IL-based SP and for all MD selection methods.