Point of Contact:
Dr. Gary Seng

Web Developer:
Rick Cowin

• Self-Assembled Materials: Certain chemical groups, e.g., hydroxyl groups or strong dipoles, on a polymer or organic molecule can produce strong non-bonded interactions between molecules or polymer chains. These interactions can lead to an ordering or assembly of molecules very much like sticks tightly packed in a bundle. Self-assembled materials might offer unique mechanical properties since these non-bonded interactions will act as "soft" cross-links between polymer chains. For most cross-linked polymers, there is usually a trade-off between strength and toughness. However, it may be possible to exploit the "soft" cross-links in self-assembled materials to achieve both high strength and high toughness. Self-assembled materials can also be used as a template upon which to attach groups with special electrical or photonic properties. This templating would serve to align the eletro-active or photonic groups to maximize their performance. This type of self-assembled material would have potential applications in sensors, electrode materials and polymer electrolytes for batteries, and proton exchange membranes for fuel cells.
• Dendrimers and Hyper-branched Polymers: Dendrimers are spherical, highly symmetrical branched macromolecules. These compounds have been shown to have interesting melt behavior that may make them useful as additives to improve the processability of high temperature polymers and polymer matrix composites. However their potential applications extend beyond the limits of structural materials. Recent developments have shown that it is possible to synthesize dendrimers that have different chemical groups on their exterior than they have in the core. These multifunctional dendrimers could find potential applications in sensors and energy storage materials. For example, a dendrimer could be synthesized that had a fluorescent core that could be quenched by electron transfer and an outer shell that contained electron donating groups that could quench the core. The extent of this electron transfer would be controlled or mediated by the polarity of the dendrimer's environent, and the intensity of the fluorescence from the dendrimer core would change (increase or decrease) depending upon the environment.

Power:

• NanoEnergy Storage Concepts

The object of this task is to asses the "practical" technical feasibility of utilizing nanotubes for revolutionary energy storage concepts: (a) hydrogen storage, (2) hydrogen/air battery. The advancement of nanotechnologies will require a long-term, high-risk approach, with a potential payoff expected to be extremely large. The revolutionary development approach proposed here embodies the strategy of investing at a relatively modest level for a "proof of concept". The carbon nanotubes will be investigated to determine its potential as a hydrogen storage system and a design of a hydrogen/air battery. Recent reports in the literature claim that it is possible to store hydrogen in carbon nanotubes. This task is to verify those claims as well as looking into doping the nanotubes to determine the effects of modifying the carbon chemical structure. If storage capability does indeed exist,

• Does it show significant improvement to current hydrogen storage methods?
• Can it be incorporated into a viable system? How many charge/discharge cycles are possible?
• Is the surrounding gas (hydrogen) pressure a contributing factor to the rate of hydrogen release/storage?

In addition, this task will investigate the use of carbon nanotubes to build a hydrogen/air battery. The bipolar plates will be build out of a nanotube composite and will store hydrogen. The fuel cell will continue to run until hydrogen is exhausted from the plates. It will need time to be recharged but no external supporting system is needed, more like a battery. It offers the potential to be an extremely light-weight system.

Lithium Battery Nanotube Anodes

The objective of this task is to produce and evaluate chemical vapor deposited carbon nanotube anodes for thin film lithium ion batteries. In contrast to carbon black, directed structured nanotubes and nanofibers offer a superior intercalation media for Li ion batteries. Carbon lamellas in carbon blacks are circumferentially oriented and block much of the particle interior, rendering much of the matrix useless as intercalation material. In contrast, nanofibers can be grown so as to provide 100% accessibility of the entire carbon structure to intercalation. Moreover, this high accessibility also confers a high mobility to ion exchange processes, a fundamental for dynamic response of batteries based on intercalation.

Nanotubes will be grown via chemical vapor deposition methods using high temperature furnaces. In this process, the catalyst is prepared prior to growth by standard techniques. Through control of the process temperature and reactive gas-phase species, nanotubes of different lengths and orientations can be grown. Catalyst preparation methods include a) in-situ preparation by decomposition of a metal salt, b) precipitated colloids or c) preformed nanoparticles synthesized by aerosol methods. Each of these techniques offers advantages for control of particle composition and size. Moreover, each is compatible with a variety of substrates materials suitable as battery electrode material. Upon preparation and/or deposition of the catalyst on the substrate, nanotubes may be grown by CVD. Control of the gas temperature is used to enable nanotube growth while minimizing pyrolytic decomposition and subsequent amorphous carbon deposition. Reactant gases such as CO or C2H2 will be used to aid in selection of the graphitic content of the nanotubes. The as-deposited nanotube morphologies will be analyzed using high resolution SEM, TEM and atomic force microscopies. The Li capacity for the different nanotubes will then be compared by electrochemical analysis of battery half-cells. Finally, the nanotube films will be incorporated into a prototype thin film lithium battery that utilizes a hybrid lithium electrolyte and lithium cobaltate cathode. These batteries will be characterized in terms of their overall capacity, rate of discharge, and cyclability.

• Instrumentation:

Quantum Entanglement For Sensing Systems and Nanoscale (NEMS) Transceivers"

The objective of this research is to verify and advance revolutionary experiments that have demonstrated a "non-local" quantum relationship between elementary particles, also known as Quantum Entanglement (QE), at a distance (>10km). The experiments used quantum mechanically entangled particles (photons, electrons, neutrons, etc) and have demonstrated effects that have the potential of revolutionizing current sensing and communication methodologies. This technology could solve the ongoing problem of how to communicate with, or otherwise extract information from, a Nano-scale Electromechanical Systems (NEMS) device. This work does not simply strive to miniaturize existing devices, but instead leverage the intrinsic scale of elementary particles.

Photonic Interrogation and Control of NanoArrays

The principle focus of this study is to develop a new photonic technology which delivers optical energy to nano-swarms or a multitude of nano-objects and/or nanodevices via a device-local holographic grating. The grating will decode photonic instructions by redirecting the photons to specific regions of the nano-swarm. The energy will interact with each nano-device by generating heat, initiating or terminating a chemical reaction, controlling an opto-electrical process, and/or through photon pressure to generate a mechanical force. This induced force will selectively and intelligently control the activity of the nano-devices. The grating will also store the device "genetic code." The grating can be constructed optically or chemically, but will be interrogated and energized photonically.

Early efforts will employ modeling and simulation at optical frequencies and micro scales, and will support development of coherent x-ray imaging technology for nano scales. Artificial neural networks will be used for fast array image processing and comparison with computational models.

Development of Silicon Carbide Nanotubes (SiCNT) for Sensors and Electronics

The objective of this task is to evaluate multiple approaches to synthesize and characterize the highest performing SiCNTs for high temperature & high radiation conditions. Also to develop sophisticated modeling and simulation technologies that will facilitate the research and development of various chemical techniques for SiC-based nanotube (SiCNT) fabrication and to further expedite the design and prototyping of more complicated assemblies and devices made from SiCNTs.

Multiple synthetic approaches are planned which parallel the direct CNT formation as well as an indirect approach involving derivatization of a CNT to a SiCNT. One indirect approach that may be envisioned to produce a SiCNT, which can be thought of as a chemical derivative of a CNT, starts with a CNT that is modified by chemically attaching different Silicon-containing functional groups to the CNT (functionalizing). This derivatized-CNT is then pyrolyzed in an appropriate environment to yield a SiCNT. A more direct approach would employ Chemical Vapor Deposition (CVD) using reduced partial-pressures of reactants and trace amounts of catalysts to directly obtain SiCNTs . This more direct fabrication attempt would rely on high temperature (2000°C) CVD using a catalytic (trace metal) substrate.

Once fabricated, the SiCNTs electrical and mechanical properties would be characterized and compared with theoretical SiCNT modeling results. The electrical properties include investigations into potential semiconductor properties that could be extended to higher (than CNT) temperatures. Electrical activity of SiCNTs could also be studied as a function of adsorbates, which could ultimately lead to applications such as nano-gas-sensors for harsh environments. Mechanical properties to be studied include tensile and compressive stress for structural components (e.g. actuators) and also their effect on SiCNT electrical properties. Knowledge gained from these fabrication results and empirical investigations can be incorporated into the models of the simulation environment to improve fidelity.