Cleavable Monomers
Figure 1. The introduction of x cleavable bonds within the strands of pDCPD with c crosslinks provides degradation fragments with ⟨c/(x + 1)⟩ crosslinks per strand. Source: Jeremiah Johnson, MIT.
“The cleavable monomer will provide a modest increase in the overall cost, on the order of ~10%, though this is only an estimate and with the identification of new synthetic routes it may be lower,” says Shieh.
“Moreover, this cost can become negligible in the context of composites, when high-value reinforcement materials such as carbon fiber are used,” he adds.
In addition, the researchers believe their approach could apply to a range of other plastics and polymers, such as rubber.
“This work unveils a fundamental design principle that we believe is general to any kind of thermoset with this basic architecture,” says Johnson.
“This will benefit all classes of thermosets, including thermoset plastics, elastomers, and gels. We could also install cleavable bonds into thermoplastics to render them degradable,” believes Shieh.
The team now is working on incorporating the cleavable comonomers into industrial resins: “In our manuscript, we demonstrated using cleavable monomers to make the industrial thermoset poly-dicyclopentadiene (pDCPD) degradable and recyclable. We are now exploring opportunities to commercialize our approach, including identifying strategic partners, to implement our approach on scale,” says Johnson.
The team also is in discussions to commercialize its silyl ether monomers for research use. An initial techno-economic analysis on the synthesis of the silyl ether monomer indicates a minor impact on the overall cost of material.
“Our comonomers can be viewed as ‘additives’, meaning they can simply be blending into an existing liquid resin and curing can follow the same manufacturing workflow without need for other changes. We hope that this approach will simplify adoption of the technology, since infrastructure changes should be precluded,” Johnson concludes.
