Researchers have developed a process1 to make thermosets—plastics once stuck in their final forms due to cross-linking of chemical bonds—that can now be reshaped and reused. Mixing polymers that have “shape memory” with other materials could produce stronger and stiffer composite parts that can be recycled or reprocessed.
Thermosets, e.g. the strong plastics of car tires or golf balls, are not as easily deformed by heat or other forces as are malleable plastics, such as those in recyclable water bottles. The work, on the cover of the journal Macromolecules, creates materials with triple-shape memory, i.e., polymers can transform from one temporary shape to another temporary shape at one temperature, then back to the original shape at another temperature. The researchers’ recipe overcomes prior challenges by allowing formulators to adjust the transformation temperature and shift material performance. A patent has been filed for the method, which uses off-the-shelf chemicals that can be easily scaled for bulk materials manufacturing.
Shape-shifting temperatures can be tuned by controlling the ratio of chemicals used in materials synthesis. The ability to control a material’s shape-memory behavior provides great design flexibility. Thermoset applications are likely to be broad, from carbon fiber and glass fiber composites for vehicles to binding glue for rare-earth-free magnets.
