There is a type of plastic called thermoset which is found in products that have to be durable and heat-resistant. Although it does a great job when being used, it also creates a lot of pollution when being discarded because it cannot be easily recycled or broken down.
Chemists at MIT have now figured out a way to alter thermoset plastics to make them much easier to break down, but still allow them to maintain the strength that makes them so practical in daily use.
Better yet, the researchers found that once that they produced a degradable version of the thermoset plastic, they could then further break it down into a powder, and use that powder to create more plastics. With this, you could recycle old tires into new ones.
“This work unveils a fundamental design principle that we believe is general to any kind of thermoset with this basic architecture,” said Jeremiah Johnson, a professor of chemistry at MIT and the senior author of the study.
The work began with a paper published last year. In it, Johnson and his team reviewed a method for creating degradable polymers by incorporating a building block, or monomer, containing a silyl ether group.
In their new paper, the researchers found that if the silyl ether monomer made up between 7.5 and 10% of a thermoset plastic called pDCPD, the plastic would retain its mechanical strength but could be broken down into a powder through the use of fluoride ions.
“That was the first exciting thing we found,” Johnson added, “we can make pDCPD degradable while not hurting its useful mechanical properties.”
In the second part of their work, the researchers played around with the powder that resulted from the degradable pDCPD. They found that the new plastics they formed from the powder had even improved mechanical properties compared to the original material in some ways.