X-ray basal reflections of several HDTMA-vermiculites show that when these contain co-adsorbed molecules of HDTMA-Br, their interlayer spacings are ∼29.5 Å. After HDTMA-Br has been leached out with ethanol, spacings decrease to ∼26 Å, but when exposed to toluene vapor the spacings increase to ∼36 Å, and to ∼45 Å in toluene liquid. Transmission X-ray diffraction photographs of HDTMA-vermiculites, both with and without co-adsorbed HDTMA-Br, indicate that they have highly ordered interlayer structures. The structure of HDTMA-Br-free vermiculite flakes is more open with the interlayer cations arranged in a 3a × b superstructure. In the HDTMA-Br containing HDTMA vermiculite flakes, HDTMA-Br molecules occupy interstitial positions between the HDTMA cations. Swelling in toluene vapor does not disorder the 2-dimensional arrangement of interlayer cations, but disorder does occur in toluene liquid. In toluene vapor, the aliphatic chains of the cations remain partially interdigitated, but in toluene liquid the interdigitation disappears. In response to the layer-charge density, the organization of the interlayer HDTMA units is caused by the self-assembly process responsible for hydrocarbon close packing.

This paper provides an overview of directed self-assembly (DSA) options that exhibit potential for enabling extensible high-volume patterning of nanoelectronics devices. It describes the current set of research requirements, which a DSA technology must satisfy to warrant insertion consideration, and summarizes the state-of-the art. The primary focus is on chemical patterning and graphoepitaxial approaches to directing block copolymer (BCP) based assembly. These options exhibit the nearest-term potential, among the emerging DSA technologies, for satisfying projected International Technology Roadmap for Semiconductors (ITRS) patterning requirements. The paper concludes with a selected set of additional challenges, which represent potential barriers to the integration of directed BCP patterning into a nanoelectronics manufacturing line, as well as a few emerging application opportunities for related functional materials. A glossary of acronyms and terms may be found at the end of this manuscript.

The self assembly of C60-N, N′-dimethylpyrrolidinium iodide (C60-DMePyI) in binary liquid mixtures has been investigated. C60-DMePyI self-organized into nanosheets in a mixture of toluene and iodomethane, and aggregated to form nanofibers in toluene. The dimensions of the nanosheets were several micrometers in length and about 100 nm in thickness. Scanning electron microscope observations indicated that a large number of nanorods having a diameter of about 20-nm formed matted nanosheets. When iodomethane alone was used as a solvent, supramolecular structures such as nanofibers and nanosheets were not produced. Structural analyses of the C60-DMePyI aggregates were carried out by laser Raman spectroscopy and x-ray diffraction (XRD). The Raman spectroscopic results suggested that an ordered chain of successive polyiodine units was formed in all the supramolecular aggregates. The XRD studies showed that the crystal systems of the nanosheets and nanofibers were monoclinic, though with different unit cells.

Poly (vinyl alcohol)–mediated synthesis of monodisperse, self-assembled, superparamagnetic maghemite particles was carried out through a magnetic field–induced biomimetic route. Modifying the kinetics of precipitation, the magnetic field promoted the nucleation of the maghemite phase over magnetite and also induced a self-assembly–assisted shape anisotropy during the precipitation of the particles in the polymer matrix.