The ). The values of The values of C S -1 at 20 mN/m and at 25°C were also dependent on the molar fraction of CyP-OBu in the monolayer (Figure ). Indeed, the strong decrease of the compressibility modulus was proportional to the increase of the molar fraction (0 to 0.4) whatever the isomer mixed with DPPC. The inverse trends were observed for molar fractions above 0.4 where C S -1 increases with the switch concentration. Finally, a more significant fluidization of the DPPC membrane was observed when the E-isomer is considered. Indeed, for a given mole fraction, C S -1 is consistently lower for a monolayer composed of DPPC/E-CyP-OBu than DPPC/Z-CyP-OBu. However, all the values for binary mixtures are lower than for a pure DPPC monolayer, thus confirming the overall fluidification.