0.45


 0.35
 ~ d
 zc b
 --0.25


 S0.15


 0.05

 1 3 5 7 9 11 13 15
 x; (m Nlm)

Figure 4-28. Compressibility plots of Figure 4-27 (PEO60-b-PCL35, target pressure 16 mN/m).
 a: PCL crystallization at 13.5 mN/m during the 1st compression. b: PCL
 crystallization at 12.5 mN/m during the 2nd and 3rd COmpressions. c: broad PCL
 melting transition during the 1st expansion. d: PCL melting transitions during the 2nd
 and 3rd expansions.

 Crystallization of the linear PEO-b-PCL diblock copolymers in the LB monolayers was

finally evidenced by AFM imaging after transfer onto mica substrates for surface pressures

above 13.5 mN/m, after crystallization of the PCL segments on the water surface took place. As

shown in Figure 4-29 for a surface pressure of 15 mN/m, all the samples show hair-

like/needlelike crystal structures, with a constant crystal thickness around 7.5 nm as determined

from cross-section analysis. This thickness is consistent with the value obtained for the PCL

homopolymers and the star-shaped block copolymer samples. The PEO chains are adsorbed onto

the mica substrate and the PCL segments stretch perpendicularly to the interface, folding

approximately every 8 e-caprolactone repeat units. These results confirm what we observed for

the star-shaped PEO-b-PCL samples, where the PEO block highly influenced crystallization of

the PCL segments in terms of crystal morphology. Nevertheless, it is crucial to emphasize here