this surface pressure range. PCL crystals were also observable, with spherulitic architectures

significantly different from those obtained by Esker and co-workers directly at the A/W interface

using BAM.101,119 This suggests that the AFM images recorded above monolayer collapse are not

only the result of PCL crystallization at the A/W interface but also the result of additional PCL

crystallization taking place during and after transfer. By use of cross-section analysis (Figure 4-

8f), all the PCL crystals were determined to be approximately 7.5 nm thick, which is consistent

with the previously reported literature on PCL lamellae thickness.131 The thickness was

independent of PCL molecular weight, which indicates that the chains stretch perpendicular to

the surface and fold every 7.5 nm, with the crystals probably growing parallel to the surface.

Nevertheless, further comparison between PCL crystallization in LB films and the previously

reported work on PCL crystallization in bulk,132 fTOm an organic solution,133 Or even in thin

filmsl34-136 remains difficult to make because different types of variables are involved.



 20 nm

 10 nm

 0 nm








 7.5 nm





Figure 4-8. Topographic AFM images of PCL homopolymers LB films transferred below and
 above monolayer collapse: PCL2000 at 7 (a) and 13 mN/m (b and c), and PCL10000
 at 7 (d) and 11.2 mN/m (e). (f) Cross-section analysis performed at the edge of a
 PCL2000 crystal.