Our electronic gadgets are notoriously difficult to recycle and have created waste problems few know how to deal with. The challenges of breaking down electronics begin with their plastic encasement: It is tedious to take apart, yet hazardous to burn or melt. Now researchers report that they have designed new plastics that break down upon exposure to light. Plastics are composed of long, repeating chains of small molecules. The researchers heated a solution of molecules derived from fructose—the basic building blocks for their plastics—and molecules that can absorb light to make long chains that form the plastics, which appeared as pale brown solids. The light-absorbing molecules break off from the chains when exposed to ultraviolet light at 350 nanometers wavelength, triggering degradation of the plastics. In a proof-of-concept experiment, the new plastics dissolved into a clear solution after being exposed to ultraviolet light for 3 hours, indicating that they were completely reduced to their soluble building-block molecules. The building-block molecules can be recovered to make new plastic, reducing demand for raw materials and waste generation, the team reports online this month in Angewandte Chemie International Edition. More research is needed to understand how the use of a light-absorbing component influences the plastics’ properties, such as strength and durability, they say, before improved versions can be developed and commercialized.
