Colloidal Lignin Nanoparticles Photonic Glasses

Lignin, the main aromatic polymer in plant biomass, has great potential as a renewable alternative to fossil-based polymers, particularly for advanced materials like photonics. Its unique structure makes it a strong candidate for creating high-performance materials. However, producing lignin-based photonic materials has been difficult due to challenges such as the use of harmful solvents and low production efficiency. These issues limit the sustainable use of lignin in material science, especially for applications that need to be environmentally friendly and scalable.

In this study, we developed a highly efficient, eco-friendly method for making colloidal lignin particles of varying sizes using only ethanol and water as solvents. This approach significantly improves production efficiency while addressing environmental concerns tied to traditional methods. The majority of crude lignin can be transformed to photonic glasses, which marks a major step forward in sustainable lignin-based photonic material manufacturing. Moreover, we showed that the color of these photonic glasses can be precisely tuned across the visible spectrum. By adjusting the rate at which water is added during the formation of lignin nanoparticles, we created a range of colors, including yellow, blue, and green. This process allows for the production of materials with specific optical properties, while ensuring the color remains consistent regardless of the viewing angle due to the short-range order typical of colloidal glasses.

Our method addresses several long-standing issues, including the need for efficient production, the use of environmentally safe solvents, and customizable optical properties. By refining how lignin nanoparticles are formed, we offer a new, scalable way to create colorful, sustainable materials with minimal environmental impact.