This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Natural materials, ranging from butterfly wings to mother-of-pearl, can exhibit an array of optical effects. In trying to reproduce these effects, scientists have found it challenging to use biodegradable, sustainable raw ingredients while also achieving the high levels of reflectivity required for certain applications.
Now, in a study published in Advanced Materials, a team led by University of Osaka researchers has developed a new process that can make highly reflective surfaces from sustainable, plant-based raw materials. Earlier work in this field used minerals or petroleum-based compounds to synthesize useful products such as pigments. Later work turned to natural, organic components, including liquid crystals and cellulose, but struggled to achieve the high reflectivity needed for optical systems.
These efforts were hampered by both the low reflectivity of natural materials and a lack of advanced processing methods. To address this, the research team considered new approaches to processing polysaccharides, which are naturally occurring compounds made of chains of sugar molecules. "This work was based on the use of xerogels," points out lead author Takaaki Kasuga.
"These are highly porous solids made by drying gels without allowing any shrinkage." The study used a technique known as electrodeposition to form 100 alternating layers of pectin, a natural material found in plants and often used in jams, and nanofibers of cellulose, the main component of plant cells. "The specific process that was used, together with the unique properties of the pectin and cellulose, generated layers that were either dense or highly porous," says senior author Masaya Nogi. "These alternating layers had very different optical characteristics, and the contrast between the two led to extreme reflectivity in the finished product." The final product showed greater than 95% reflectance at a variety of wavelengths of light, including nonvisible light.
Although there are some examples of reflective materials in nature, such as the brilliant armor of the jewel beetle, the jewel beetle reflects only 30% of light. The products generated in this work have potential applications in optical sensors, decorative displays and anticounterfeiting technologies. The researchers also found that after some tweaking of the material's chemical composition, these naturally sourced layers could be made to degrade by up to 80% in just two months, meeting the standard benchmark for biodegradability.
By reflecting near-infrared light while allowing visible light to pass through, these new materials could also help keep houses cool in the summer when used as windows. This is likely just the beginning: Because the color, pattern and performance of these films can all be finely tuned, this approach points toward a future of sustainable coatings, labels and building materials that could one day replace their synthetic, nonbiodegradable counterparts. Takaaki Kasuga et al., Over 95% Optical Reflectance From Structurally Modulated All‐Biopolymer Multilayers, Advanced Materials (2026).
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