Processing and Applications of Carbon Nanotubes, Graphene, and Beyond Professor Mark C. Hersam Department of Materials Science and Engineering Northwestern University http://www.hersam-group.northwestern.edu/ Students: Matt Duch, Niki Mansukhani, Linda Guiney UC CEIN All-Center Retreat Ventura, California September 28, 2013
Introduction to Carbon-Based Nanomaterials A. K. Geim and K. S. Novoselov, Nature Materials, 6, 183 (2007). 2-D: Graphene 0-D: Fullerene 1-D: Nanotube 3-D: Graphite
Carbon Nanotube Polydispersity Reviews: Nature Nanotechnology, 3, 387 (2008); MRS Bulletin, 35, 315 (2010). Current synthetic methods yield polydisperse mixtures of CNTs. Post-synthetic methods for sorting by diameter, electronic type, chiral handedness, and number of walls are highly desirable.
Isopycnic Separation of Carbon Nanotubes Nature Nanotechnology, 1, 60 (2006); Nature Nanotechnology, 4, 64 (2009). Density gradient ultracentrifugation (DGU) allows CNTs to be sorted by diameter and/or electronic type (metal versus semiconducting). DGU also allows multi-walled CNTs to be sorted by wall number. Enantiomeric enrichment is achieved with chiral surfactants.
DGU of Graphene Nano Letters, 9, 4931 (2009). Exfoliate graphite powder via sonication in aqueous solution with the planar surfactant sodium cholate. DGU enables sorting by the number of graphene layers.
Scalability of Density Gradient Ultracentrifugation http://www.nanointegris.com/ 10,000x scale up of metal and semiconductor IsoNanotubes TM and graphene PureSheetsTM; 500+ customers in 40+ countries
Electronics with Semiconducting CNTs Review: Chemical Society Reviews, 42, 2824 (2013). ACS Nano, 6, 7480 (2012). APL, 101, 053123 (2012). Thin-film transistors 150 GHz RF electronics Nano Lett., 13, 954 (2013). Nano Lett., ASAP (2013). Printed digital circuits Sub-Nanowatt CMOS
Applications for Solution Processed Graphene Review: Chemical Society Reviews, 42, 2824 (2013). Nano Lett., 12, 1184 (2012). JPCL, 2, 3006 (2011). GHz flexible electronics Organic photovoltaics Nano Lett., 11, 2865 (2011). JPCL, 4, 1347 (2013). TiO2 NS SEG TiO2 NP photocatalysis 400 µm Conductive printable inks
Beyond Surfactants: Biocompatible Polymers Nano Letters, 10, 1664 (2010). Collaboration with Scott Budinger and Gokhan Mutlu (NU Medical School) In vivo pulmonary toxicity in mice drops to undetectable levels when SWCNTs are well dispersed using biocompatible polymers (e.g., poloxmers)
Pluronic and Tetronic Block Copolymers ACS Nano, 4, 4725 (2010). LINEAR X-SHAPED Pluronic and Tetronic block copolymers have tunable hydrophilic (PEO) and hydrophobic (PPO) segments Nonionic character has potential advantage for electronic and electrochemical applications
DGU with Pluronic Encapsulated SWCNTs ACS Nano, 4, 4725 (2010). Pluronic F108 Pluronic F68 Pluronics isolate semiconducting SWCNTs in DGU Banding pattern and SWCNT purity depend on block copolymer structure (semiconductor purity increases with decreasing PPO length)
Minimizing Toxicity of MWCNTs with Pluronic Nano Letters, 12, 3050 (2012). Collaboration with Andre Nel (UC CEIN) Exposure to MWCNTs dispersed in BSA or MWCNTs poorly dispersed in Pluronic F108, results in increased levels of IL-1β, increased cell death, decreased cell viability, and low stability index levels. Well dispersed MWCNTs in Pluronic F108 exhibit minimal toxic response and show exceptional stability.
Pluronics/Tetronics also Disperse Graphene Journal of Physical Chemistry Letters, 2, 1004 (2011). Sweet spot for dispersing graphene Dispersion efficiency of graphene depends on the molecular weights of the hydrophobic (PPO) and hydrophilic (PEO) blocks
Minimizing Toxicity of Graphene with Pluronic Nano Letters, 11, 5201 (2011). Pluronic-dispersed graphene shows significantly reduced toxicity compared to aggregated graphene or graphene oxide
Gadographene as an MRI Contrast Agent Journal of Physical Chemistry C, 117, 16263 (2013). A variety of gadolinium compounds can be tethered to graphene, yielding enhanced longitudinal (r1) and transverse (r2) relaxivities as high as 85 mm-1s-1 and 24-115 mm-1s-1, respectively.
Environmental Studies of Carbon Nanomaterials Environ. Sci. Technol., 46, 11752 (2012). Environ. Sci. Technol., 47, 6288 (2013).
Post-Graphene 2-D Nanomaterials Nature Nano, 7, 683 (2012). Example TMDCs: MoS2, WS2, MoSe2, WSe2 MoS2 is attracting the most interest currently MoS2 is an n-type direct band gap semi-conductor, which makes it promising for: S Mo Nature Nano, 7, 699 (2012). Electronics Optoelectronics Photovoltaics Catalysis Biomedical imaging