Conventional metal-catalyzed organic radical reactions and living radical polymerizations (LRP) performed in nonpolar solvents, including atom-transfer radical polymerization (ATRP), proceed by an inner-sphere electron-transfer mechanism. One catalytic system frequently used in these polymerizations is based on Cu(I)X species and N-containing ligands. Here, it is reported that polar solvents such as H(2)O, alcohols, dipolar aprotic solvents, ethylene and propylene carbonate, and ionic liquids instantaneously disproportionate Cu(I)X into Cu(0) and Cu(II)X(2) species in the presence of a diversity of N-containing ligands. This disproportionation facilitates an ultrafast LRP in which the free radicals are generated by the nascent and extremely reactive Cu(0) atomic species, while their deactivation is mediated by the nascent Cu(II)X(2) species. Both steps proceed by a low activation energy outer-sphere single-electron-transfer (SET) mechanism. The resulting SET-LRP process is activated by a catalytic amount of the electron-donor Cu(0), Cu(2)Se, Cu(2)Te, Cu(2)S, or Cu(2)O species, not by Cu(I)X. This process provides, at room temperature and below, an ultrafast synthesis of ultrahigh molecular weight polymers from functional monomers containing electron-withdrawing groups such as acrylates, methacrylates, and vinyl chloride, initiated with alkyl halides, sulfonyl halides, and N-halides.

The effect of solvent on the two-dimensional (2D) supramolecular ordering of monodendron 1 at the liquid-solid interface has been systematically investigated by means of scanning tunneling microscopy (STM). Solvents range from those with hydrophilic solvating properties, such as alkylated alcohols and acids, to hydrophobic solvents such as alkylated aromatics and alkanes. Dramatic differences in the 2D ordering are observed depending on the nature of the solvent. Of particular interest is the fact that in hydrophobic solvating solvents, such as aliphatic and aromatic hydrocarbons, solvent molecules are coadsorbed in the 2D molecular network while this is not the case for alkylated alcohols or acids. Furthermore, in the case of the coadsorbing solvents, a striking influence of the alkyl chain length has been observed on the 2D pattern formed. The solvent and alkyl chain length dependences are discussed in terms of molecule-molecule interactions (homo and hetero) and molecule-substrate interactions.

The single‐electron transfer living radical polymerization (SET‐LRP) of methyl acrylate initiated with bromoform (CHBr3) and iodoform (CHI3) and catalyzed by Cu(0)/Me6‐TREN in DMSO at 25 °C provides a reliable method to prepare poly (methyl acrylate) (PMA) with active chain ends and controlled structure that can undergo subsequent functionalization to provide strategies for the synthesis of different block copolymers and other complex architectures. A detailed kinetic and structural analysis was used to assess the scope and the limitations of CHBr3 and CHI3 as initiators under SET‐LRP conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 278–288, 2008

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Keeping nature under control: The internal structure of helical porous protein mimics self‐assembled from hybrid dendritic dipeptides is programmed by the stereochemistry of the dipeptide and regulated allosterically. This is the first example of a synthetic helical porous supramolecular structure that is stable both in solution and in the solid state, and that is created by a sequence of events related to those encountered in nature.

Wer die Natur beherrschen will: Die innere Struktur der helicalen Poren in Proteinmimetika, die selbstorganisiert aus Dendrit‐Dipeptid‐Hybriden entstehen, wird durch die Konfiguration des Dipeptids festgelegt und allosterisch gesteuert. Als erste synthetische supramolekulare Struktur mit helicalen Poren ist die Architektur sowohl in Lösung als auch im Festkörper stabil; zudem ähnelt die Schrittfolge bei ihrer Bildung einem natürlichen Prozess.

Montmorillonite clays modified with 1,5-bis(3-aminophenoxy)-3-oxapentane dihydrochloride (BAOD) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon BAOD were prepared and examined for their dispersion behavior in the polymer matrix. Initial evaluation was performed by preparing high molecular weight poly(amide acid) solutions in the presence of the organoclays at a 3 wt% loading. Films were cast and subsequently heated to 300 °C to cause imidization. The resulting nanocomposite films were characterized by transmission electron microscopy and x-ray diffraction. It was found that the clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in nanocomposite films prepared from organoclays possessing medium and high CECs. One organoclay that dispersed well was further evaluated in nanocomposite films at weight loadings of 5 and 8%. The nanocomposite films were characterized by transmission electron microscopy, x-ray diffraction, and thin-film tensile testing. High levels of clay dispersion were achieved even at the higher clay loadings. Mechanical testing of these films showed that the moduli of the materials increased with increasing clay concentration, but the strength and elongation were generally adversely affected.