The Japan Advanced Institute of Science and Technology (JAIST) will start R&D of edible bioplastics that control degradability by incorporating photocatalysts. By including in its bioplastics a photocatalyst that can trigger to switch hydrophobicity to hydrophilicity, JAIST will create plastics that turn into gel in the ocean and do not damage the body even when eaten by living organisms. This gel is non-toxic and will slowly decompose in the environment.
It has previously been pointed out that partly decomposed biodegradable plastics may actually pose issues as microplastics. To try and help deal with this, JAIST aims to develop plastics that are safe even when released into the environment, achieving this through the processes of microplastic detoxification, softening and decomposition.
Having already brought about hydrophilization as an underlying technology, JAIST has tested a solid resin which has undergone hydrophilization processing by being exposed to strong ultraviolet rays for six hours, with the result here showing that this resin is able to dissolve in water. By deploying this technology to bioplastics, it is possible to create bioplastics that turn into a non-toxic gel, which is harmless even if eaten by marine organisms.
The material used here is sorghum, a tall biomass that can be grown all over Japan and has excellent productivity. Itaconic acid is synthesized from this biomass, and is then used to produce polymer fibers that are polycondensed with molecules that have an optical switch function.
While the switch functionality here serves to trigger decomposition when exposed to water and light, it is not possible to control this process directly. However, the triggering can be controlled by embedding the photocatalyst in with the fiber. By putting together a fiber with a layered core-in-sheath structure, the photocatalyst inside is exposed to the outside only when the polymer on the surface is damaged, at which point the material’s biodegradability activates.