Reusable, Self-healing Plastic?

May 22, 2014 By Anita R
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From computer parts, to the water bottle, school bag, automobile parts, even the clothes we wear, plastic has become indispensable in our lives.

While plastic is cheap, durable, flexible and strong, it is also hard to dispose off and has been a major source of pollution on Earth. This is because plastic does not biodegrade or decompose easily. Until now...

A research team, led by Jeannette Garcia from IBM, has made an accidental discovery. They have come up with a new class of plastics which has all of plastic's properties and yet is 100% recyclable. The new polymer, code named Titan, could be the perfect solution to our polymer dilemma.

Plastics - The 'Thermo' way

Lets first understand a little bit about the nature of plastic. The word plastic comes from the Greek word plastikos, meaning “moldable” or “formable.” When heated to a liquid or semisolid form, plastics can be molded into almost any desired shape. Depending on how plastics react to heat, they could be one of two kinds.

Thermoplastics soften with heat and will remain soft as more heat is applied. They set only when cool and so can be softened many times by reheating. They are great when you want plastic objects to hold heat. If you closely examine the plastic molecules, thermoplastic chains are loose.

Thermoset plastics, however, harden permanently or set after being heated once. The process of thermosetting could be done either by heating or using chemicals through a process called curing. While curing, the molecules of the plastic link together between chains through cross-links, after which plastic will no longer become soft. There is no turning back here - sort of like the way cement turns into concrete.

A Happy Accident!

IBM’s new polymer (scientific name: polyhexahydrotriazine, or PHT) is a thermosetting plastic. Not only is it stronger, light weight and completely recyclable, but this new plastic is also self-healing. Imagine an iPhone that can heal itself after a crack!

The discovery, however, began as an accident. Jeannette Garcia, a chemist, was working on a type of polymer. She had forgotten to add an ingredient before heating the mixture, and noticed that the solution in her flask had suddenly hardened. She had to smash the flask with a hammer, and, even then, she couldn’t break the material itself. Garcia didn’t know how she had created this new polymer, and approached IBM’s computational chemistry team to recreate the process.

Wondering what it means for us? Quite a bit. PHT or Titan can replace modern plastics in a majority of devices we use everyday, as well as find use in everything from aircrafts to automobiles. Besides, it could save our world from tons of new plastic debris. Sounds like a win-win to us!

Critical Thinking: What could be some of the devices you would use Titan for? Can you think of other accidental discoveries that have helped make our lives easier while being environmentally efficient?

Courtesy: BBC