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Saturday, April 20, 2024

Column: Of pencils and deodorant

Often, the best new technology comes from learning about everyday phenomena.

For instance, take graphene. Graphene is a sheet of carbon atoms that are structured in a way similar to chicken wire, except this carbon “chicken wire” is less than half of a nanometer wide. A nanometer is 0.000000001 meter, or (as is the common reference point) about 1/1,000 the width of a human hair. Its structure as a sheet could lend it many different possibilities depending on how it is folded or rolled, from lasers to building materials in vehicles.

Such a material must be really difficult to manufacture, right? Actually, you’ve probably accidentally made a tiny amount today while taking notes. Graphene is derived from graphite, which is what pencils use today instead of lead. When graphite is worn down, such as when you write on paper, a tiny amount of that graphite is torn off in atomic sheets of graphene.

Graphene is what is known as a nanomaterial, a class of substances that are being eagerly researched for their many human applications.

One of those researchers is Alexandra Navrotsky, a professor of ceramic, earth and environmental materials chemistry at UC Davis. She is also the director of the Nanomaterials in the Environment, Agriculture and Technology – Organized Research Unit (NEAT ORU) at UC Davis.

“The fundamental definition of a nanomaterial is a material whose dimensions are small enough to change their properties,” Navrotsky said.

Navrotsky explained that this doesn’t necessarily occur at a certain size, but rather, depends on the material used. Normally, though, it happens at around the nanometer scale (hence, the name).

“[The nanomaterial] may change color, magnetic or structural properties. The reactivity on the surface and the biological activity may also change,” Navrotsky said.

Again, graphene illustrates the change. As you know if you’ve ever used a pencil (hopefully a fairly large percentage of readers), graphite is a rather soft, dark material. Graphite and graphene are both composed completely of carbon, but once you purify large sheets of graphene things start to get interesting. Despite one sheet being about an atom thick, it can still be seen by the naked eye (though it isn’t dark like graphite).

Navrotsky herself does not work specifically with graphene, but does work with a very large variety of other materials.

Navrotsky’s work in the lab is largely focused on the heat and energy properties of nanomaterials. Though she works mostly with synthetic nanomaterials, nature still has the lead in production.

“Synthetic samples are more controlled than natural samples, but the environment will always have nanomaterials,” Navrotsky said. “Nature’s been doing this for millions of years.”

Nanomaterials are spewed from volcanoes, thrown upward from ocean spray and created in the atmosphere between gases and dust particles. Both natural and synthetic nanomaterials have been used in products we use every day.

Do you wear deodorant? Most of them are composed of aluminum inside of a nano-sized cluster of atoms. Ever see a fabric advertised as antibacterial? A lot of them work by having particles that trigger reactions that kill bacteria.

Navrotsky does encourage caution in using nanomaterials, particularly synthetic ones.

“When introducing new materials into the environment, one should always be concerned with the effects,” Navrotsky said.

According to Navrotsky, a new nanomaterial can affect the environment in two ways: chemically or biologically. A new reaction in an environment not adapted to it can affect both the chemistry of the environment or the biology of the surrounding life forms.

“There has been a discussion on silver particles and how they affect life forms,” Navrotsky said. “It is interesting, but the jury is still out. Each chemical has to be considered separately, as silver may do one thing while aluminum does another.”

Synthetic and natural nanomaterials are here to stay; if we’re careful with how we use them, tiny materials can help us do big things.

AMY STEWART can be reached at science@theaggie.org.


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