• Tangle no more, nanotubes

    From ScienceDaily@1:317/3 to All on Wednesday, April 27, 2022 22:30:50
    Tangle no more, nanotubes
    Solvent simplifies industrial 3D, roll-to-roll carbon nanotube printing
    and more

    Date:
    April 27, 2022
    Source:
    Rice University
    Summary:
    Scientists have developed an acid-based solvent that simplifies
    carbon nanotube processing in a way that's less toxic and easy to
    scale up for industrial applications.



    FULL STORY ========================================================================== Carbon nanotubes that are prone to tangle like spaghetti can use a little special sauce to realize their full potential.


    ==========================================================================
    Rice University scientists have come up with just the sauce, an acid-based solvent that simplifies carbon nanotube processing in a way that's easier
    to scale up for industrial applications.

    The Rice lab of Matteo Pasquali reported inScience Advances on its
    discovery of a unique combination of acids that helps separate nanotubes
    in a solution and turn them into films, fibers or other materials with excellent electrical and mechanical properties.

    The study co-led by graduate alumnus Robert Headrick and graduate student Steven Williams reports the solvent is compatible with conventional manufacturing processes. That should help it find a place in the
    production of advanced materials for many applications.

    "There's a growing realization that it's probably not a good idea to
    increase the mining of copper and aluminum and nickel," said Pasquali,
    Rice's A.J.

    Hartsook Professor and a professor of chemical and biomolecular
    engineering, chemistry and materials science and nanoengineering. He is
    also director of the Rice-based Carbon Hub, which promotes the development
    of advanced carbon materials to benefit the environment.

    "But there is this giant opportunity to use hydrocarbons as our ore,"
    he said.

    "In that light, we need to broaden as much as possible the range in which
    we can use carbon materials, especially where it can displace metals
    with a product that can be manufactured sustainably from a feedstock
    like hydrocarbons." Pasquali noted these manufacturing processes produce
    clean hydrogen as well.



    ========================================================================== "Carbon is plentiful, we control the supply chains and we know how to
    get it out in an environmentally responsible way," he said.

    A better way to process carbon will help. The solvent is based on methanesulfonic (MSA), p-toluenesulfonic (pToS)and oleum acids that,
    when combined, are less corrosive than those currently used to process nanotubes in a solution. Separating nanotubes (which researchers refer
    to as dissolving) is a necessary step before they can be extruded through
    a needle or other device where shear forces help turn them into familiar
    fibers or sheets.

    Oleum and chlorosulfonic acids have long been used to dissolve nanotubes without modifying their structures, but both are highly corrosive. By
    combining oleum with two weaker acids, the team developed a broadly
    applicable process that enables new manufacturing for nanotubes products.

    "The oleum surrounds each individual nanotube and gives it a very
    localized positive charge," said Headrick, now a research scientist at
    Shell. "That charge makes them repel each other." After detangling,
    the milder acids further separate the nanotubes. They found MSA is best
    for fiber spinning and roll-to-roll film production, while pToS, a solid
    that melts at 40 degrees Celsius (104 degrees Fahrenheit), is particularly useful for 3D printing applications because it allows nanotube solutions
    to be processed at a moderate temperature and then solidified by cooling.



    ==========================================================================
    The researchers used these stable liquid crystalline solutions to make
    things in both modern and traditional ways, 3D printing carbon nanotube aerogels and silk screen printing patterns onto a variety of surfaces, including glass.

    The solutions also enabled roll-to-roll production of transparent films
    that can be used as electrodes. "Honestly, it was a little surprising
    how well that worked," Headrick said. "It came out pretty flawless on
    the very first try." The researchers noted oleum still requires careful handling, but once diluted with the other acids, the solution is much
    less aggressive to other materials.

    "The acids we're using are so much gentler that you can use them with
    common plastics," Headrick said. "That opens the door to a lot of
    materials processing and printing techniques that are already in place
    in manufacturing facilities.

    "It's also really important for integrating carbon nanotubes into other devices, depositing them as one step in a device-manufacturing process,"
    he said.

    They reported the less-corrosive solutions did not give off harmful fumes
    and were easier to clean up after production. MSA and pToS can also be
    recycled after processing nanotubes, lowering their environmental impact
    and energy and processing costs.

    Williams said the next step is to fine-tune the solvent for applications,
    and to determine how factors like chirality and size affect nanotube processing.

    "It's really important that we have high-quality, clean, large diameter
    tubes," he said.

    Co-authors of the paper are alumna Lauren Taylor and graduate students
    Oliver Dewey and Cedric Ginestra of Rice; graduate student Crystal Owens
    and professors Gareth McKinley and A. John Hart at the Massachusetts
    Institute of Technology; alumna Lucy Liberman, graduate student Asia
    Matatyaho Ya'akobi and Yeshayahu Talmon, a professor emeritus of chemical engineering, at the Technion-Israel Institute of Technology, Haifa,
    Israel; and Benji Maruyama, autonomous materials lead in the Materials
    and Manufacturing Directorate, Air Force Research Laboratory.

    The research was supported by the Air Force Office of Scientific Research (FA9550-12-1-0035, FA9550-15-1-0370, FA9550-19-1-7045), the Robert
    A. Welch Foundation (C-1668), the Department of Energy (DE-EE0007865, DE-AR0001015), the NASA Space Technology Research Institute (NNX17AJ32G),
    a NASA Space Technology Research Fellowship (NNX14AL71H), a National
    Defense Science and Engineering Graduate Research Fellowship and the
    United States-Israel Binational Science Foundation (2016161).


    ========================================================================== Story Source: Materials provided by Rice_University. Original written
    by Mike Williams. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Robert J. Headrick, Steven M. Williams, Crystal E. Owens, Lauren W.

    Taylor, Oliver S. Dewey, Cedric J. Ginestra, Lucy Liberman,
    Asia Matatyaho Ya'akobi, Yeshayahu Talmon, Benji Maruyama, Gareth
    H. McKinley, A. John Hart, Matteo Pasquali. Versatile acid solvents
    for pristine carbon nanotube assembly. Science Advances, 2022; 8
    (17) DOI: 10.1126/ sciadv.abm3285 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220427140621.htm

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