where stable monolayers could be formed for surface pressures as high as 40 mN/m before

collapsing (Figure 5-6). After 20 minutes of reaction (= 50 % extent of cross-linking according to

the isobar at pH = 3.0 and zi= 10 mN/m), the cross-linked material becomes more hydrophobic

and can be clearly observed in Figure 5-10C (bright areas) with an average height of 1 nm as

determined by cross-section analysis (Figure 5-10E). The cross-linked PB has irregular borders

and does not cover yet the entire mica surface. An AFM image obtained after completion of the

cross-linking reaction is shown in Figure 5-10D (10 h, pH = 3.0, K = 10 mN/m). Under these

experimental conditions, most of the mica surface was covered with a smooth and cross-linked

monolayer. Therefore, we deliberately found an area with a crack (that probably formed during

film transfer) to clearly show the presence of the cross-linked monolayer (bright area) on top of

the mica substrate with a thickness that stays constant around 1 nm during cross-linking (Figure

5-10F).

 The acid-catalyzed condensation between the triethoxysilane pendant groups of a

hydrosilylated PB obtained by hydrosilylation of a commercial PB homopolymer has been

successfully applied in this preliminary investigation to the preparation of cross-linked polymeric

monolayers without any reagents or additives directly at the A/W interface. This technique opens

up the possibility to retain a specific 2D morphology at the nanoscopic scale as exemplified in

the following part for PB-b-PEO three-arm star block copolymers.