anionic polymerization as described in detail elsewhere [I 51. Dry block copolymer was dissolved in toluene (5 mgmL-I ) . Tetrachloroauric acid (HAuCI,) was added to the block copolymer solution in the required amounts given in molar relation to the 2VP units (HAuC1,/2VP = 0.5 was maintained for this work). The solution was subsequently stirred for 24 h. Solutions of lower concentration were obtained by diluting a part of this stock solution with toluene followed by an additional 24 h stirring.
Thin film preparation: A freshly cleaved piece of mica was dipped into the solution. Typically, the substrate was immersed in the solution for 20 min. The mica plate was taken out of the solution and immediately brought into contact with a piece of filter paper in order to remove the solution and dry the surface rapidly.
Scanning force microscopy: The adsorbedjprecipitated surface layer of the block copolymers was investigated using a Nanoscope 111 (Digital Instruments, St. Barbara) using the tapping mode [16]. The oscillation frequency w a ~ ca. 360 kHz depending on the Si-cantilever which had a spring constant of about 50 Njm. The optimal operating point for the tapping frequency was chosen as far as possible on the low frequency side of thc non-contact resonance curve [17]. The tip radius used was checked by a calibration standard 1181 and was found to he 8 nm for good tips and 15 nm for had ones.