Researchers must find a sustainable way of providing the power our modern lifestyles demand.

Building better batteries

http://nathan.instras.com/ResearchProposalDB/doc-109.pdf

A review on polymer nanofibers by electrospinning and their applications in nanocomposites

The large-scale practical application of fuel cells will be difficult to realize if the expensive platinum-based electrocatalysts for oxygen reduction reactions (ORRs) cannot be replaced by other efficient, low-cost, and stable electrodes. Here, we report that vertically aligned nitrogen-containing carbon nanotubes (VA-NCNTs) can act as a metal-free electrode with a much better electrocatalytic activity, long-term operation stability, and tolerance to crossover effect than platinum for oxygen reduction in alkaline fuel cells. In air-saturated 0.1 molar potassium hydroxide, we observed a steady-state output potential of –80 millivolts and a current density of 4.1 milliamps per square centimeter at –0.22 volts, compared with –85 millivolts and 1.1 milliamps per square centimeter at –0.20 volts for a platinum-carbon electrode. The incorporation of electron-accepting nitrogen atoms in the conjugated nanotube carbon plane appears to impart a relatively high positive charge density on adjacent carbon atoms. This effect, coupled with aligning the NCNTs, provides a four-electron pathway for the ORR on VA-NCNTs with a superb performance.

http://science.sciencemag.org/content/sci/323/5915/760.full.pdf

Nitrogen-doped carbon nanotube arrays with high electrocatalytic activity for oxygen reduction.

Research in the use of organic polymers as the active semiconductors in light-emitting diodes has advanced rapidly, and prototype devices now meet realistic specifications for applications. These achievements have provided insight into many aspects of the background science, from design and synthesis of materials, through materials fabrication issues, to the semiconductor physics of these polymers.

Electroluminescence in conjugated polymers

A general all-atom force field for atomistic simulation of common organic molecules, inorganic small molecules, and polymers was developed using state-of-the-art ab initio and empirical parametrization techniques. The valence parameters and atomic partial charges were derived by fitting to ab initio data, and the van der Waals (vdW) parameters were derived by conducting MD simulations of molecular liquids and fitting the simulated cohesive energies and equilibrium densities to experimental data. The combined parametrization procedure significantly improves the quality of a general force field. Validation studies based on large number of isolated molecules, molecular liquids and molecular crystals, representing 28 molecular classes, show that the present force field enables accurate and simultaneous prediction of structural, conformational, vibrational, and thermophysical properties for a broad range of molecules in isolation and in condensed phases. Detailed results of the parametrization and validation f...

COMPASS: An ab Initio Force-Field Optimized for Condensed-Phase ApplicationsOverview with Details on Alkane and Benzene Compounds

Light-emitting diodes using n-type conducting polymer

Effect of sulphate ion on the electrochemical polymerization of pyrrole and N-methylpyrrole

Infrared spectra and structure of silicon cobalt tetracarbonyls

Acetylene was first polymerised to a linear polymer in 19581 but the resulting grey powdery material, insoluble, infusible, and devoid of any interesting electrical properties, remained a scientific curiosity until Ito et al.2 showed that it was possible to polymerise acetylene into a continuous film on the wall of a reactor. This polyacetylene film, (CH)x, a large band gap semiconductor, can be transformed into a highly conducting material with σRT∼ 1,000 (Ω cm)−1 (refs 3–12) upon doping with either electron donors or acceptors13,14. Although fibrous electron micrographs (EM) of unaligned2 and partially aligned (stretch elongated) samples having enhanced conductivities have been reported3, it has been suggested that the observed morphology might be misleading, possibly resulting from a post-polymerisation handling of the film, or even an artefact such as the result of ultrasonication. The aim of this work is to determine the true nascent morphology of polyacetylene. We have polymerised acetylene directly on electron microscope gold grids and examined the polymer with scanning and transmission modes. The ultrathin specimen is entirely fibrous with diameters of ∼5–40 nm, with 20-nm fibrils the most abundant. Some films show surface fractures revealing partially or completely aligned fibrils bridging the gaps. Some globular features were also observed suggesting local fusion. Thick films of polyacetylene also have fibrous morphology throughout. The observed structure is consistent with surface area measurements. Therefore, acetylene polymerises directly into fibrils, possibly due to the rigidity of the polymer backbone which is comprised of conjugated double bonds.

Nascent morphology of polyacetylene

We report the crossover for the microwave dielectric constant of camphor-sulfonic-acid-doped polyaniline prepared in m-cresol from very large room-temperature negative values to large positive ones with decreasing temperature below ${\mathit{T}}_{\mathit{s}}$\ensuremath{\sim}20 K. We attribute this change to the transition from a phonon-controlled metallic state to a nonmetallic state with localized carriers and hopping transport below ${\mathit{T}}_{\mathit{s}}$. Electronically, one-dimensional chains that couple the three-dimensional crystalline regions are likely central for understanding the origin of this transition as weak localization. At T${\mathit{T}}_{\mathit{s}}$ we also observed an increase in the thermoelectric power and a linear decrease in the reduced activation energy for dc conductivity.

Alan G. MacDiarmid

Papers

Light-emitting diodes using n-type conducting polymer

Effect of sulphate ion on the electrochemical polymerization of pyrrole and N-methylpyrrole

Infrared spectra and structure of silicon cobalt tetracarbonyls

Nascent morphology of polyacetylene

Phonon-induced nonmetal-metal transition of a doped polyaniline.