By Frank Rovella
If you find yourself going
straight for the technology section every time you get online or open a paper,
then you’re not alone. There are a lot of us just waiting for the next big
thing, seeking to be awed by some new technological development. The Industrial
Space is fertile ground for this enterprise; just take a look at emerging
materials technology.
Unlike automation that has a
level of predictability akin to a train that always runs on time; we can see it
downrange, hear the tracks rumble, and watch it flash by. However, materials technology is more like a
seismic event, we know it’s coming but no one is sure when or how big it’s
going to be.
An example is a recent
discovery by the French physicist Ludwik Leibler, who is this year’s winner of
the European Inventor Award in the category research. Leibler along with his team at the
Laboratoire Matière Molle et Chimie at ESPCI ParisTech, have developed a whole new class of plastics called Vitrimers.
"Classified as supramolecular
substances, Vitrimers are a derivative of thermoset plastics and exhibit
self-repairing characteristics."
What’s really intriguing
about Vitrimers is how they do what they do. To understand this, we’ll have to
look at the mechanics of their most basic elements. At the molecular level, the atoms that
comprise standard thermosets maintain their crystalline structure through
permanent or rigid chemical bonds, the strength of these bonds ultimately
determines the characteristics of the material. Flex, friction, and thermal cycles
break down these bonds resulting in weakening that leads to cracks and
fractures. Once these bonds are broken, they cannot be repaired However, the molecular bonds
that makeup Vitrimers are neither permanent nor rigid; their state is more
akin to a dynamic equilibrium. This means that molecular bonds are forming and
breaking simultaneously. Regardless of the molecular structure, the number of bonds
remains the same. This reaction is thermally activated allowing VItrimers to go
from solid to liquid and back with no change in crystalline structure; this is
known as a glass transition. These characteristics, in essence, are what make
Vitrimers a self-repairing plastic. Testing conducted at the
University of Minnesota concluded that fractured samples that were healed
recovered 102% of tensile strength, 133% of the original tensile modulus value,
and 67% of ultimate elongation. Vitrimers glass-like qualities, allow it to be
welded like glass, meaning that if two surfaces are brought to a molten state
and welded, when they solidify the molecules are aligned like a solid section,
with no seam. This is similar to friction stir welding, but far more complete.
The self-repairing qualities
of Vitrimers are paving the way for a number of impressive innovations, and
will surely lead to many more. One of
these is in the medical industry, where Vitrimers are being used in what is
being called “Organ Glue.” This is a self-healing polymer hydrogel that acts as
an anti-hemorrhaging, wound-healing aqueous solution. Vitrimers have the
ability to form “nanobridging”, that is a molecular bridging of tissue; it can
be used in situations where stitches are impractical.
For the more mundane,
however, these same self-healing properties can make a significant impact on
manufactured goods. Self-repairing plastics means that products made from it
will have a far longer service life. Simply put less material is required
because fewer parts are needed to accommodate for wear.
Then there are the effects on
recycling, Vitrimers by nature are ideal for recycling because they can be
liquefied and solidified over and over. Think about all the plastic that can’t
be recycled, they end up in landfills, and some of these plastics can take
hundreds of years to decompose fully. Vitrimers could make plastics as
recyclable as aluminum.
The concept of materials that
self-repair, or do things that seem physically impossible certainly has an awe
factor, but Vitrimers are just one example. NASA is currently developing
materials that can self-heal after a meteor strike and even self-repairing
alloys. As we move forward keep your eyes open, because there is a lot more
from this came from.
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