Scientists create brilliant white material without a drop of white pigment

This effect is known as structural whiteness. Rather than relying on a colored substance, it emerges from the way a material's microscopic structure interacts with light.

The same basic phenomenon appears throughout nature. Sea spray, clouds, and snow all look intensely white because their structures scatter visible light extremely efficiently. Similar effects can be found in plant tissues and even in the foamy protective nests made by some frogs. In many cases, these structures consist largely of air, yet they can produce striking whiteness without any pigment.

That natural strategy inspired an international team led by Professor Easan Sivaniah of Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS), working with researchers from Tokyo Metropolitan University and Donghua University. Their goal was to create a new foam-based materials platform that could address two major challenges facing commonly used materials.

Alternatives to Titanium Dioxide and PFAS

White packaging, films, and coatings often depend on titanium dioxide (TiO₂), which provides both brightness and opacity. However, safety concerns recently prompted the European Union to ban titanium dioxide as a food additive.

Another widely used group of chemicals, known as PFAS, helps materials repel water and oil. These fluorinated substances are increasingly under scrutiny because they can persist in the environment and may pose environmental and health risks. Those concerns have intensified efforts worldwide to find alternatives.

The researchers approached both problems by focusing on physical structure rather than added chemicals. They engineered carefully controlled porous materials that imitate the way natural foams scatter light while also drawing inspiration from water-repellent surfaces found on leaves and flower petals.

"A key challenge faced by biomimetic science is realizing environmentally friendly material designs inspired by nature at the scale and cost of existing materials," said Assoc. Prof. Taiki Yanagishima of Tokyo Metropolitan University.

Light and a Mild Solvent Create the Foam

The manufacturing method is relatively simple. First, the polymer is exposed to light. That light breaks the polymer into smaller molecular fragments. The material is then treated with a mild solvent, which interacts with those fragments and causes the polymer to swell.

As the material expands, it develops an open network of microscopic pores. This single transformation gives the material two useful properties.

Inside the material, the porous structure scatters light so effectively that it appears intensely white without any added pigment. At the surface, the foam develops an extremely rough texture that strongly repels water, much like the surface of a lotus leaf.

The team calls the process Deep Foam Photolithography (DFP).

From Polymer Films to Fabrics

In collaboration with textile researchers at Donghua University, one of China's leading institutions for textile science and engineering, the researchers showed that the method works on more than just printable polymer films. It can also be applied to fabrics.

Another advantage is that the process does not depend on developing entirely new specialty chemicals. The researchers have already demonstrated DFP using several commercially available polymers.

The resulting printable materials platform can achieve ultrahigh resolution (20,000 DPI). At the same time, it combines structural whiteness with water-management functionality without titanium dioxide and without PFAS.

Building Function Into the Material Itself

The approach could create new opportunities for lighter materials while reducing reliance on mined mineral pigments and persistent fluorinated chemicals.

Instead of adding pigments to produce color or applying persistent chemical coatings to control how surfaces interact with water, the researchers build those properties directly into the material's physical structure.

By using microscopic architecture to control light and water, the technology offers a fundamentally different and potentially more sustainable approach to designing everyday materials. Rather than depending primarily on chemistry, the material itself is structured to provide the desired function.