Engineering news
Pic cap: New ultra-strong polymer reinforced with carbon nanotubes
IBM Research has demonstrated a new class of polymers that could have the potential to transform manufacturing and fabrication in transport, aerospace, and microelectronics.
By combining high-performance computing with synthetic polymer chemistry, the researchers discovered a new class of polymers that are resistant to cracking, stronger than bone, can reform to its original shape (self-heal), and completely recyclable. Also, these materials can be transformed into new polymer structures to increase their strength by 50%, making them ultra strong and lightweight.
The new class of polymers, formed through a condensation reaction where molecules join together and lose small molecules as by-products such as water or alcohol, are incredibly tunable.
At low temperatures and with inexpensive starting chemicals one polymer is formed that is stronger than most existing polymers, but still maintains its flexibility because of solvent that is trapped within the structure. If this material is heated to high temperatures, the polymer becomes even stronger due to a rearrangement of covalent bonds and the loss of the solvent, but as a consequence is more brittle.
Additionally, polymers constructed using the same technology but instead formed by reacting small, flexible pieces of a polymer, this new material displays very different properties than the ultra-strong polymers previously discussed. Instead of being robust, brittle, and strong, they form gels with the solvent that they are produced in that are elastic.
The researchers said the most unexpected and remarkable characteristic of these gels is that if they are severed and the pieces are placed back in proximity so they physically touch, the chemical bonds are reformed between the pieces making it a single unit again within seconds. This "self healing" polymer is made possible due to hydrogen-bonding interactions in the hemiaminal polymer network.
The polymers remain intact when they are exposed to water, but selectively decompose when exposed to very acidic water. This means that under the right conditions, the polymer can be reverted back to its starting materials, which enables it for reuse for other polymers, which would enable manufactures to reduce costs and save waste. The material can also be manufactured to have even higher strength if carbon nanotubes or other reinforcing fillers are mixed into the polymer and are heated to high temperatures.
James Hedrick, advanced organic materials scientist at IBM Research, said: “Although there has been significant work in high-performance materials, today’s engineered polymers still lack several fundamental attributes. New materials innovation is critical to addressing major global challenges, developing new products and emerging disruptive technologies.
“We’re now able to predict how molecules will respond to chemical reactions and build new polymer structures with significant guidance from computation that facilitates accelerated materials discovery. This is unique to IBM and allows us to address the complex needs of advanced materials for applications in transportation, microelectronic or advanced manufacturing,” added Hendrick.