successive compression-expansion curves shift toward the low MMA region only below 6.5

mN/m. Above 6.5 mN/m, the curves overlap because the amount of PCL2000 adsorbed at the

A/W interface stays constant, independent of the number of compression-expansion hysteresis

cycles.




 *E 0 mol% PCL2000
 E 10 -1 \\ 28 mol% PCL2000
 Z 51 mol% PCL2000
 0 I 70 mol% PCL2000
 "~~ 6 10 86 mol% PCL2000
 xc (mNlm)
 -100 mol% PCL2000


 0 1000 2000 3000 4000
 Mean Molecular Area (A2)

Figure 4-22. Isotherms of PEO2670 and PCL2000 binary mixtures. (Inset) Corresponding
 compressibility plots versus surface pressure.


 *First compression
 8 First expansion
 E o Second compression
 S 6 *Second expansion






 0 1000 2000 3000 4000
 Mean Molecular Area (A2)

Figure 4-23. Compression-expansion hysteresis plot of the binary mixture with 49 mol % in
 PEO2670 (target pressure = 9 mN/m).

 It is also interesting to notice that the collapse surface pressure of PEO2670 slightly

increases (up to 6.7 mN/m for 86 mol % of PCL2000) when increasing the amount of PCL2000