Pioneering natural, degradable polymer capsules

Polymer capsules can store functional substances such as drugs and fragrances, making them widely used in functional cosmetics and daily necessities. However, conventional capsules use non-degradable polymers and are difficult to decompose in natural environments. They are identified as a contributing factor to the marine microplastics problem, and concerns have been raised about their impact on the ecosystem and human health.

In search of an alternative, a research group led by Associate Professor Yukiya Kitayama at Osaka Metropolitan University’s Graduate School of Engineering pioneered a new technology for preparing polymer capsules using naturally occurring molecules. Their method produces polymer particles from photoreactive monomers that are formed by the ester bond condensation of natural molecules, such as cinnamic acid found in certain plants and glycerol found in lipids, by irradiating them with light. Furthermore, polymeric capsules that store target molecules can be obtained while removing unreacted monomers.

The researchers also found that the naturally-derived polymer capsules have a stable shelf life of a year and are easily degradable. The capsules undergo photodegradation upon exposure to short-wavelength light and they can also be degraded by hydrolyzing the ester bonds contained within the polymer.

“This polymer capsule can stably encapsulate low-molecular-weight fluorescent dyes and fragrances. Furthermore, by expanding the synthesis scale to 100 times that of conventional methods while maintaining process safety, we have demonstrated its potential for industrialization,” says Professor Kitayama. “We aim to establish new design guidelines for environmentally friendly materials while applying them across diverse fields such as pharmaceuticals, cosmetics, fragrances, and fertilizers.”

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