Biodegradation Control of Ocean-Degradable Plastics by Photo-Switching

Abstract

As the global production of plastics increases, marine pollution caused by plastic waste has become a growing problem. Biodegradable plastics are therefore expected to become an environmentally low-impact material.　However, biodegradable plastics are subject to microbial action during use, and biodegradation progresses moment by moment, resulting in a decrease in molecular weight and physical properties, which makes them unreliable as a material and has been an obstacle to their widespread use. In order for biodegradable plastics to be widely used, they are required to maintain their physical properties as a product without biodegrading during a certain period of use in the ocean, and at the same time, they are required to decompose quickly after being discharged into the ocean. In other words, a switch function is required to maintain mechanical and other physical properties during use and to decompose quickly after use. “Light” is expected to serve as a switch for biodegradation, since the material is often exposed to sunlight during use and is not exposed to light after use, such as in the ocean. Therefore, we focused on the antibacterial activity of photocatalysts, composited biodegradable plastics with visible-light-sensitive photocatalysts, and evaluated the antibacterial activity (suppression of biodegradation) of the resulting composites under light irradiation.