1 nmp







 5 nmp

 0 nm no i



Figure 3-3. Topographic AFM images ofDendl LB films transferred at 5 (a), 10 (b), 15 (c), 20
 (d), 24 (middle of plateau, MMA = 20,000 A+2, e and f), and 40 mN/m (g and h).

 A LB film of Dend1 was also transferred in the middle of the plateau (MMA = 20,000 A+2,

and the resulting AFM images are shown in Figures 3-3e and 3-3f. In this case, no transfer ratio

could be calculated since the barriers were manually stopped after compression before transfer,

and therefore these two AFM images only qualitatively reflect the A/W interfacial aggregation.

Nevertheless, the images clearly confirm the biphasic state of the plateau, with areas exhibiting

circular surface micelles similarly as for lower pressures and other areas with aggregated

domains significantly thicker (~ 3 nm) than the PS micellar cores. It was previously suggested

that at the beginning of the plateau region, the tert-butyl groups reorient from prone to vertical,

with further compression leading to film collapse.10 Since PtBA is a hydrophobic polymer, it

collapses by aggregating on top of the water surface. The aggregated areas observed in Figures

3-3e and 3-3f therefore likely correspond to desorbed Dend1 mono or multilayers. Compression-

expansion hysteresis experiments (3 cycles) were carried out in the plateau region, and the

resulting curves are shown in Figure 3-4. All the compression curves closely overlapped,

indicating that the collapsed films are able to go back to their original adsorbed monolayer state