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JULY 2019        TAP TIMES          -13-



               MIT finds Do-It-Yourself
                 nanotube ingredients




            aking soda, table salt, and deter-
        Bgent are surprisingly effective in-
        gredients for cooking up carbon nano-
        tubes, researchers at MIT, Cambridge,
        Mass.  have found.
                                                                Ingredients  found  in  most  kitchens  are  able  to  catalyze
                                                                carbon nanotube growth, according to MIT researchers.
        Sodium-containing compounds                             The bond between carbon atoms is extraor-
        In a study published this in Angewandte                 dinarily strong,  and  when  patterned  into
        Chemie, the team reports that sodium-                   a lattice, such as graphene, or as a tube,
        containing compounds found in common                    such as a CNT, such structures can have ex-
        household ingredients are able to catalyze              ceptional stiffness and strength, as well as
        the growth of carbon nanotubes, or CNTs,                unique electrical and chemical properties.
        at much lower temperatures than tradi-
        tional catalysts require.
                                                                Stronger, tougher materials
        The researchers say that sodium may                     As  such,  researchers  have  explored  coat-
        make it possible for carbon nanotubes to                ing various surfaces with CNTs to produce
        be grown on a host of lower-temperature                 stronger, stiffer, tougher materials.
        materials, such as polymers, which nor-
        mally melt under the high temperatures                  Researchers typically grow CNTs on various
        needed for traditional CNT growth.                      materials through a process called chemi-
                                                                cal  vapor  deposition.  A  material  of  inter-
        “In aerospace composites, there are a lot               est,  such  as  carbon  fibers,  is  coated  in  a
        of polymers that hold carbon fibers togeth-             catalyst—usually  an  iron-based  compound
        er, and now we may be able to directly                  —and  placed  in  a  furnace,  through  which
        grow CNTs on polymer materials, to make                 carbon dioxide and other carbon-containing
        stronger, tougher, stiffer composites,” said            gases flow.
        Richard Li, the study’s lead author and a
        graduate student in MIT’s Department of
        Aeronautics and Astronautics.                           Vertical tubes around carbon fibers
                                                                At temperatures of up to 800 degrees Cel-
                                                                sius, the iron starts to draw carbon atoms
        Unlocking friendly surfaces                             out  of  the  gas,  which glom  onto  the  iron
        “Using sodium as a catalyst really unlocks              atoms and to each other, eventually form-
        the kinds of surfaces you can grow nano-                ing vertical tubes of carbon atoms around
        tubes on.”                                              individual carbon fibers.

        Under a microscope, carbon nanotubes re-                Researchers then use various techniques to
        semble  hollow  cylinders  of  chicken  wire.           dissolve  the  catalyst,  leaving  behind  pure
        Each tube is made from a rolled up lattice              carbon nanotubes.
        of hexagonally arranged carbon atoms.                                                          Next page
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