Yale University
225 Prospect Street
New Haven, CT 06520
phone: 203.432.5215
greenchemistry@yale.edu

Materials

  • Environmentally and Economically Sustainable Carbon Nanotube Manufacturing

     Details...
    Carbon nanotubes (CNTs) consist of carbon atoms arranged into hollow cylinders with high length-to-diameter ratios. This “nanotube” geometry gives CNTs several unique properties and therefore widely applicable to the structural, electrical, optical, and energy fields. However, as their demand has increased over the past several decades, we must be concerned with the potential environmental impacts associated with CNT production. How to environmentally sustainable produce CNT is a huge issue facing by the CNT manufacturer. 

    STUDY

    Detailed understanding the chemical process in the CNT manufacturing is our first step. Through chemical analytical tools in our lab, we could understand the bond-building steps in nanocarbon formation. With our specially designed reactors, we can deliver trace amounts of any gas and study the role of each gas in nanocarbon formation. By correlating each intermediate concentration with the CNT properties, we can determine the most efficient and direct pathway to form CNTs. We propose that by intentionally delivering only the necessary reactants for CNT production, we can reduce the formation of the unwanted environmental pollutants, reduce the energetic costs of the CNT synthesis, and simultaneously improve the quality of the CNT.

    IMPACT

    Understanding the mechanism of CNT formation on the molecular level could lead to a CNT manufacturing market that will simultaneously improve production efficiency, CNT quality, and environmental sustainability. This successful experience could also be applied to other emerging nanomaterial productions and fabrications in future.

     

    PUBLICATIONS 

    Early Evaluation of Potential Environmental Impacts of Carbon Nanotube Synthesis by Chemical Vapor Deposition. Environ. Sci. Technol., 2009, 43(21), 8367-8373

    Multiple Alkynes React with Ethylene To Enhance Carbon Nanotube Synthesis, Suggesting a Polymerization-like Formation Mechanism. ACS Nano, 2010, 4(12), 7185-7192

  • Catalytic Transformation of Biomass

     Details...
    Development of new earth-abundant metal catalysts for selective transformation of lignin model compounds and lignocellulosic biomass.

    This project aims to selectively defunctionalize lignin while preserving aromaticity and a useful degree of complexity.  It is important to develop biomass as a renewable source of chemicals but we must strive to do so in a sustainable fashion.  Conversion of lignin from agricultural waste and energy crop residues to higher-value products has potential to produce chemicals and fuels without competing with food resources.  The fundamental catalytic chemistry has already been established for the most part using precious metals.  The price and scarcity of these metals may exclude them from practical applications in industrial-scale biomass conversion.  Our goal is to use cheaper, more abundant metals for these catalytic steps.  The chemistry of the expensive metal complexes can be used to help guide the development of cheaper metal alternatives.  The development of catalysts based on abundant metals would have important impacts beyond biomass chemistry as well.

  • Advancing Sustainable Nanotechnology: Safer Carbon Nanotubes (CNTs) and CNT-Enabled Products

     Details...
    Carbon nanotubes (CNTs) are a class of nanomaterials that have the potential to significantly impact human health and the environment in both positive and negative ways. The vast number of CNT applications range from antimicrobial coatings, conductive thin films, advanced battery technology, and high strength composites. The unique properties that inspire these promising applications are also the cause of environmental and human health concern. This application-implication paradox serves as the motivation for our research, which focuses on better understanding the underlying physicochemical properties of CNTs that govern specific responses (e.g. antimicrobial and reactivity). 

    We have ongoing research projects that focus on both the molecular and product level. At the molecular level, various techniques are used to systematically modify the surface chemistry of single- (SWNT) and multi-walled (MWNT) carbon nanotubes and thus, alter their physical and chemical properties. At the product level, our work seeks to evaluate the environmental and human health impacts associated with the production and implementation of nano-enabled products. In doing so, we established a quantitative approach to evaluating upstream impact and downstream benefit tradeoffs that can be applied to emerging technologies.   

    The application of our holistic and comprehensive approach to nanomaterial and nano-enabled product systems advances the establishment of property-hazard relationships to simultaneously enhance nanomaterial functional properties and reduce the potential for unintended consequences, ultimately enabling a sustainable future for the nanotechnology industry.

  • Sweeteners and Other Flavor Agents Relevant to Existing and Emerging Tobacco Products

     Details...
    To support ongoing Yale TCORS research into the role flavor additives play in initiation and addiction to existing and emerging tobacco products, the overall objective of this project is to characterize and quantify the composition and quantity of key sweeteners and other flavor additives in salable chewable and dissolvable products as well as e-cigarettes.

    The Family Smoking Prevention and Tobacco Control Act banned the sale of tobacco cigarettes with added artificial and natural flavors.  However, this ban does not extend to chewable or dissolvable tobacco products or to electronic cigarettes.  Of particular concern with these emerging products is that certain flavors, sweeteners in particular, are thought to lower the threshold for adolescent tobacco use initiation and reinforcement.  It is known that these emerging products contain sweeteners and other flavor additives in addition to ground tobacco and nicotine.  However, the specific composition and quantity of these components are not well characterized making it difficult to replicate the impact of actual product formulations on behavior.

    The results of this project will guide the design and implementation of in vivo tests in mice and rats examining the effects of flavors on nicotine consumption and central reward pathways, with the overall goal of ascertaining the role of these additives in initiating and reinforcing tobacco product use, particularly relevant to susceptible users such as adolescents.

  • MoDRN (Molecular Design Research Network)

     Details...
    The world we live in is made of chemicals. The man-made substances have had revolutionary benefits on our lives as well as unintended consequences. MoDRN (Molecular Design Research Network) is a Green Chemistry and Green Engineering initiative, which focuses on the rational design of chemicals and materials to reduce toxicity.

    Our engineers, chemists, toxicologists and biologists are working to develop a robust, accurate and intuitive set of tools to both inform chemical toxicity levels and help scientists design less hazardous alternatives. 

    The overarching goal of MoDRN is to enable and empower the design, discovery and development of next generation chemicals that possess reduced toxicity. To accomplish this we facilitate engagement of scientists, educators, industry and regulatory bodies in this trans-disciplinary endeavor.