New material mimics strength, toughness of mother of pearl

Date:
July 15, 2020
Source:
American Chemical Society
Summary:
In the summer, many people enjoy walks along the beach looking for
seashells. Among the most prized are those that contain iridescent
mother of pearl (also known as nacre) inside. But many beachcombers
would be surprised to learn that shimmery nacre is one of nature's
strongest, most resilient materials. Now, researchers have made
a material with interlocked mineral layers that resembles nacre
and is stronger and tougher than previous mimics.



FULL STORY ==========================================================================
In the summer, many people enjoy walks along the beach looking for
seashells.

Among the most prized are those that contain iridescent mother of pearl
(also known as nacre) inside. But many beachcombers would be surprised to
learn that shimmery nacre is one of nature's strongest, most resilient materials. Now, researchers reporting in ACS Nano have made a material
with interlocked mineral layers that resembles nacre and is stronger
and tougher than previous mimics.


==========================================================================
Some mollusks, such as abalone and pearl oysters, have shells lined
with nacre.

This material consists of layers of microscopic mineral "bricks"
called aragonite stacked upon alternating layers of soft organic
compounds. Scientists have tried to replicate this structure to make
materials for engineering or medical applications, but so far artificial
nacre has not been as strong as its natural counterpart. Hemant Raut,
Caroline Ross, Javier Fernandez and colleagues noticed that prior nacre
mimics used flat mineral bricks, whereas the natural material has wavy
bricks that interlock in intricate herringbone patterns. They wanted
to see if reproducing this structure would create a stronger, tougher
nacre mimic for sustainable medical materials.

Using the components of natural nacre, the team made their composite
material by forming wavy sheets of the mineral aragonite on a patterned chitosan film.

Then, they interlocked two of the sheets together, filling the space
between the wavy surfaces with silk fibroin. They stacked 150 interlocked layers together to form a composite that was about the thickness of a
penny. The material was almost twice as strong and four times as tough
as previous nacre mimics -- close to the strength and toughness reported
for natural nacre. The artificial nacre was also biocompatible, which
the researchers demonstrated by culturing human embryonic stem cells on
its surface for one week. These features suggest that the material could
be suitable for sustainable, low-cost medical uses, the researchers say.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Hemant Kumar Raut, Alan F. Schwartzman, Rupambika Das, Fan Liu,
Lifeng
Wang, Caroline A. Ross, Javier G. Fernandez. Tough and Strong:
Cross- Lamella Design Imparts Multifunctionality to Biomimetic
Nacre. ACS Nano, 2020; DOI: 10.1021/acsnano.0c01511 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200715123136.htm

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