We synthesized an amphiphilic coil-rod-coil triblock molecule consisting of hexa-p-phenylene as a rod block and poly(ethylene oxide) with the number of repeating units of 17 as coil blocks and investigated aggregation behavior in aqueous environment. The rod-coil molecule was observed to aggregate into discrete micelles consisting of hydrophobic disklike rod bundles encapsulated by hydrophilic poly(ethylene oxide) coils. The aromatic bundles of the micelles were demonstrated to be used as an efficient supramolecular reactor for the room temperature Suzuki cross-coupling reaction of a wide range of aryl halides, including even aryl chlorides with phenylboronic acids in aqueous environment. These results demonstrate that self-assembly of amphiphilic rod-coil molecules can provide a useful strategy to construct an efficient supramolecular reactor for aromatic coupling reaction.

We synthesized ABC triblock rigid aromatic-flexible dendritic block molecules consisting of a docosyl chain, rigid aromatic segment, and poly(ethylene oxide) dendrimer. These block molecules were observed to exhibit an ordered structure in the solid state. Small-angle X-ray scattering experiments showed that the rigid-dendritic block molecule based on a more rodlike aromatic unit self-assembles into a 2-D hexagonal columnar structure, whereas the block molecule based on a more wedgelike aromatic unit self-assembles into a 3-D micellar cubic structure. Dynamic light scatterings, scanning electron microscopic (SEM) observations, and UV/vis spectroscopic measurements were carried out to investigate the encapsulation behavior of hydrophobic guests with the block molecules in an aqueous environment. The rigid-dendritic block molecules self-assemble into stable capsulelike micellar aggregates in aqueous solutions in the presence of CHCl3. In addition, the resulting micellar aggregates encapsulate hydrophobic dye molecules within their micellar core. The critical micellar concentration (cmc) values appeared to be very low, as compared to those of conventional surfactants. These results demonstrate that the introduction of a hydrophilic dendritic segment into an extended rigid aromatic segment can lead to a unique self-assembling system that shows aggregation behavior in both solid and dilute solution phases.

[reaction: see text] We have investigated supramolecular reactors for the Suzuki coupling reactions of aryl halides with phenyl boronic acids by using self-assembly of amphiphilic rod-coil molecules in aqueous solution at room temperature. All the rod-coil molecules synthesized in this work showed to self-assemble into discrete micelles consisting of aromatic rod bundles encapsulated by hydrophilic poly(ethylene oxide) coils. We present a comparative study of rod-coil molecules' efficiency as supramolecular reactors for Suzuki coupling reaction. The closed-packed aromatic bundles play an efficient role in supramolecular reactors for the coupling reactions at room temperature. The supramolecular reactor based on hexa-p-phenylene confers unprecedented activity, allowing reactions to be performed at very low catalyst levels, without conventional heating or microwave.

The effects of self-assembled monolayer (SAM) and perfluoropolyether (PFPE) lubricant on the wear characteristics of flat silicon tips were investigated. The wear test consisted of sliding the silicon tips fabricated on a flat silicon specimen against SAM and PFPE (Z-tetraol) coated silicon (100) wafer. The tips were slid at a low speed for about 15 km under an applied load of 39.2 lN. The wear volume of the tip was obtained by measuring the tip profile using an Atomic Force Microscope (AFM). It was found that the coatings were effective in reducing the wear of the tips by an order of magnitude from 10 -6 to 10 -7 .