The use of bottom-up approaches to construct patterned surfaces for technological applications is appealing, but to date is applicable to only relatively small areas (approximately 10 square micrometers). We constructed highly periodic patterns at macroscopic length scales, in the range of square millimeters, by combining self-assembly of disk-like porphyrin dyes with physical dewetting phenomena. The patterns consisted of equidistant 5-nanometer-wide lines spaced 0.5 to 1 micrometers apart, forming single porphyrin stacks containing millions of molecules, and were formed spontaneously upon drop-casting a solution of the molecules onto a mica surface. On glass, thicker lines are formed, which can be used to align liquid crystals in large domains of square millimeter size.

Spontane Vesikelbildung sowohl in organischen Lösungsmitteln als auch in Wasser wurde bei Stab‐Knäuel‐Diblockcopolymeren mit Thiophen‐Einheiten beobachtet. Die Thiophen‐Einheiten an der Oberfläche der Aggregate können unter Bildung „polymerisierter“ Vesikel verknüpft werden (siehe Bild und Titelbild). In die Vesikel können Enzyme eingeschlossen werden, wodurch katalytisch aktive Mikroreaktoren erhalten werden, deren Hülle für Substratmoleküle durchlässig ist.

A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions. The molecule-substrate interaction causes a bending of the porphyrin core which also determines the relative orientations of phenyl legs attached to the core. A major consequence of this is a characteristic (and energetically most favourable) arrangement of molecules within self-assembled molecular clusters; the phenyl legs of adjacent molecules are not aligned parallel to each other (often denoted as pi-pi stacking) but perpendicularly in a T-shaped arrangement. The results of the simulations are fully consistent with the scanning tunnelling microscopy observations, in terms of the symmetries of individual molecules, orientation and relative alignment of molecules in the self-assembled clusters.

Spontaneous formation of vesicles in both organic solvents and water is observed for new rod–coil‐type diblock copolymers containing thiophene groups. The thiophene groups located in the skin of the aggregates can couple to give polymerized vesicles (see picture and cover picture). The vesicles are capable of including enzymes, which results in catalytically active microreactors that are permeable to substrate molecules.

From simple pocket calculators, to mobile telephones and LCD-TV, over the past few decades devices based on liquid crystal display technology have proliferated into just about all conceivable aspects of everyday life. Although used in cutting-edge technology, it is surprising that a vital part in the construction of such displays relies essentially on a process invented almost 100 years ago. This essential part, the alignment layer, dictates the macroscopic uniform alignment of liquid crystalline molecules (mesogens) near its surface. The current method for manufacturing such layers is the mechanical rubbing of spin-coated polymers with a piece of velvet cloth. This very successful method is still at the basis of the production process of even the largest displays currently manufactured in industry. Unfortunately, the construction of ever larger displays with this technique is becoming a technological nightmare for engineers. Therefore, over the past decades, many alternatives to rubbing have been explored. This review will focus on advances towards achieving one of the most important goals in LCD technology: attaining rational control over the properties of nematic liquid crystal domains.

A simple method for the construction of a stable, tunable, self-assembled command layer for liquid crystal display purposes is described. A pyridine-functionalized oligosiloxane spontaneously forms an anisotropic, grooved surface on indium-tin-oxide, enabling it to align liquid crystalline molecules. The pyridine functions act as seeds for the epitaxial growth of stacks of highly ordered zinc phthalocyanines, the height of which can be controlled. These stacks increase the interaction between the surface and the liquid crystalline matrix by amplifying the surface ordering into the liquid crystal bulk. By varying the height of the stacks, direct control over the properties of the liquid crystal domains is achieved. These properties can be further tuned by adding to the liquid crystal, micro-and nanomolar concentrations of nitrogencontaining compounds, which are capable of interacting with and dissolving the stacks. The procedures we describe offer possibilities to use such tunable systems in LCD-based sensor devices as well as in solar-cell applications.

No abstract

Crucial for the development of enhanced electrooptic materials is the construction of highly anisotropic materials. Nematic liquid crystals are able to control the chain conformation and alignment of poly(phenylene ethynylene)s (PPEs), producing electronic polymers with chain-extended planar conformations for improved transport properties. Here, we show that the dichroic ratio, and hence polymer alignment, increases dramatically when interpolymer interactions are introduced by end capping the PPE with hydrogen bonding groups. This increased order can be readily turned off by the introduction of a competing monofunctionalized hydrogen bonding compound. The formation of hydrogen bonds between the polymers results in the formation of gels and elastomers which may be of interest for future applications.