Things are meant to break. How many times has a child been soothed because the favorite, unfixable toy was thrown in the trash? And how does it look repairing a chip in the front car window without replacing the window entirely? And God forbid your better half breaks Grandma’s 200-year-old china. No fixing that.
But there is hope. In Sebastian, Spain at the CIDETEC Centre for Electrochemical Technologies, researchers may have discovered a way to take care of all these daily household headaches with self-healing polymers that repair by themselves.
For those who resisted studying chemistry 101, what is a polymer? Polymers are long chains of molecules that are connected by chemical bonding agents. Included in the list of polymers are:
- Proteins such as hair, tortoise-shell, human nails
- Cellulose in trees and paper
- Silly putty
Metal, elements and salt compounds are omitted from the polymer grouping.
And when studying chemistry, all scientific shoppers know that polymers also come in two varieties, natural and synthetic.
Natural polymers are everywhere. These intelligent materials can make repairs all by themselves such as in the healing of human skin tissue. For example, when a child cuts his finger, it is not the Band-Aid that heals the cut, but the self-healing natural polymers that fuse the skin back together. Although a kiss from Mom also helps.
Although natural polymers are an inherent property, synthetic polymers that were created by scientists are just as common.
During World War II, nylon and synthetic rubber was developed to replace the lack of product coming into the US such as silk and natural rubber. As the industrialized world took hold, other products such as PVC and polyester developed.
Synthetic polymers impersonate natural polymers with one big exception. Synthetic polymers do not have the inherent ability of self-healing—that is until now.
In the September issue, Materials Horizon reports that scientists have created a polymer that after being sliced and separated, the molecule can self-repair it form back to its previous, undamaged condition. What is unique to this synthetic polymer, is that the entire repair is done without use of a catalyst. Again for chemistry 101 haters, a catalyst is a substance that works to speed up a chemical reaction.
For its toughness, the synthetic self-healing polymer has been nicknamed the Terminator after the Terminator 2 T100 robot.
In researching the self-healing properties of the synthetic material, lab scientists halved a cylinder made from the polymer. The two halves were then connected back together without pressure. Within two hours, sitting at room temperature, the cylinder used in the experiment was 97 percent whole and within 22 hours the cylinder completely fused.
Twisting, stretching and banging, the Terminator could not be broken. Not even a dent could the scientists’ make.
When the polymer sat at room temperature conditions, the two separate sections of the cylinder exchanged bis(4-aminophenyl) disulfides through metathesis. This exchange enabled the regeneration to take place, not catalyst needed.
In 2011, Case Western Reserve University researchers created a self-healing polymer to be used as a coating to seal surface scratches. Their idea was to restore broken chemical crosslinks with a material when it fractures. Such as when a disgruntled employee keys along the side of your newly purchased, black truck, the polymer coating can be applied to repair the surface scratch.
The discovery of polymer’s healing attribute will create stronger sealants, paints and adhesives. But the greatest breakthrough could eventually aid those of us at home.
Instead of the consumer purchasing poorly-made products that break, using self-healing polymers to repair items such as pipes, tires, toys will put the repair money back into the consumer’s household pocket-book.
Written by Lisa Graziano