We report a direct method to amplify the exponential growth of multilayers significantly by the alternating deposition of polyethylenimine (PEI) at high pH and poly(acrylic acid) (PAA) at low pH. The alternating pH switches the degree of ionization of the polyelectrolytes in the multilayers, which enhances the diffusion of PEI into and out of the film and hence increases the deposited mass per cycle. The synergetic action of the pH-tunable charge density and diffusivity of the weak polyelectrolytes provides a new method for the enhanced growth of multilayers with hierarchal micro- and nanostructured surfaces.

occurring at ca. +1.20 V versus FeCp +/0 2 as well as reductions at potentials similar to those in our study (see (a) below). The HOMO level for perylene diimides can then be estimated as ca. 6.3 eV using E 1/2 (TPD +/0 ) -E 1/2 (PDI +/0 ) = E HOMO (TPD) -E HOMO (PDI),with E 1/2 (TPD +/0 ) = +0.26 V versus FeCp +/0 2 in CH 2 Cl 2 (see (b) below) and a value of 5.4 eV (from UV-PES; see (c) below) for E HOMO (TPD (s) Preparation and manipulation of supramolecular objects with nanometer dimensions in several of the three spatial directions are prominent goals of modern nanotechnology. [1] To date, nanosized objects, such as nanospheres, [2] nanowires, [3] or nanobelts [4] have been prepared from various materials, such as metals, ceramics, or organic polymers. Carbon nanotubes are another well-known example of supramolecular objects with one mesoscopically extended dimension and two others confined to the nanometer length scale.[5] Two-dimensionally extended nanomaterials have been prepared, e.g., from polyelectrolyte multilayers, with a thickness between 10 and 15 nm.[6] Similar freestanding polymeric membranes with thicknesses in the range of several tens of nanometers capable of spanning micrometerwide pores have been prepared from Langmuir-Blodgett monolayers of crosslinked polyisoprene, [7] from triblock copolymers, [8] and most recently from nanocomposite membranes of polyelectrolytes with embedded gold nanoparticles.[9] Extremely flat and two-dimensionally extended objects have been termed "nanosheets" and prepared, for example, by exfoliation of layered inorganic materials, with a thickness down to 1 nm and lateral dimensions up to 100 lm. [10,11] In this communication, we show the controlled preparation of individual, freestanding nanosheets with the thickness of a single biphenyl molecule. These nanosheets can span holes in the size range of several tens of micrometers. They can be prepared by electron-induced crosslinking of self-assembled monolayers and subsequent release of the material from its substrate. Self-assembled monolayers (SAMs) are highly ordered organic molecular aggregates chemisorbed on a surface with a thickness of a single molecule, i.e., in the range of a few nanometers. [12][13][14] SAMs containing aromatic bi-or terphenyl units can be laterally crosslinked by electron irradiation and are effective resist materials for nanopatterning. [15][16][17][18] During electron irradiation, carbon-hydrogen bonds are cleaved initially, followed by formation of carbon-carbon crosslinks between the aromatic units. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) [15,19,20] and infrared reflection absorption spectroscopy (IRRAS) [16] both indicate lower molecular order and reduced aromaticity of the crosslinked films.Other examples of crosslinked monolayers that have been previously reported include polymeric SAMs containing polydiacetylene units [21] and polymerized Langmuir-Blodgett films.[22] SAMs containing only aliphatic chains, such as alkanethiols on gold, are not crosslinked ...

This paper introduces an approach where the match of two different length scales, i.e., pattern from self‐assembly of block copolymer micelles (< 100 nm) and electron‐beam (e‐beam) writing (> 50 nm), allow the grouping of nanometer‐sized gold clusters in very small numbers in even aperiodic pattern and separation of these groups at length scales that are not accessible by pure self‐assembly. Thus, we could demonstrate the grouping of Au nanoclusters in different geometries such as squares, rings, or spheres.

The self-initiated photografting and photopolymerization (SIPGP) of styrene, methyl methacrylate, and tert-butyl methacrylate on structured self-assembled monolayers (SAMs) of electron beam cross-linked omega-functionalized biphenylthiols SAMs on gold was investigated. Polymer brushes with defined thickness can be prepared on crosslinked benzyl-, phenyl-, hydroxyl-, and amino-functionalized SAMs, whereas non-cross-linked SAM regions desorb from the surface during the SIPGP process. By the preparation of brush gradients on different functionalized SAMs, it was demonstrated that the resulting polymer brush layer thickness is determined by the locally applied electron beam dosage. Defined micro-nanostructured polymer brush patterns can be prepared down to a size of 50 nm. Finally, it was shown that polymer brushes obtained by the SIPGP process have a branched architecture.