Scientists Create Brilliant White Material without White Pigment

Topic: Materials Science

A team of international researchers created a new foam-based material that appears white without any added pigment. They used light and a mild solvent to create a porous structure that scatters light, making it appear intensely white. This innovation could replace materials currently made with titanium dioxide and PFAS.

Imagine looking at Hokusai's famous painting 'The Great Wave off Kanagawa'. The brilliant whites in the painting seem almost painted on, but they're not. The whiteness comes from light scattering off the fibers of traditional washi paper. This effect is called structural whiteness.

This phenomenon appears throughout nature - sea spray, clouds, and snow all look intensely white because their structures scatter visible light efficiently. A team of international researchers led by Professor Easan Sivaniah of Kyoto University's Institute for Integrated Cell-Material Sciences (iCeMS) was inspired by this natural strategy to create a new material.

The researchers wanted to address two major challenges facing commonly used materials: alternatives to titanium dioxide and PFAS. These chemicals are often used in packaging, films, and coatings, but they have safety concerns. The European Union has banned titanium dioxide as a food additive, and PFAS are under scrutiny for their environmental and health risks.

The team engineered carefully controlled porous materials that imitate the way natural foams scatter light. They also drew inspiration from water-repellent surfaces found on leaves and flower petals. The process is called Deep Foam Photolithography (DFP).

In DFP, a polymer is exposed to light, breaking it into smaller molecular fragments. A mild solvent then interacts with these fragments, causing the material to swell and develop an open network of microscopic pores. This single transformation gives the material two useful properties: it appears intensely white without any added pigment, and its surface repels water strongly.

The researchers showed that DFP can be applied not just to printable polymer films but also to fabrics. They used several commercially available polymers to demonstrate this. The resulting materials platform can achieve ultrahigh resolution (20,000 DPI) and combines structural whiteness with water-management functionality without titanium dioxide and PFAS.

Why It Matters

This innovation could lead to safer packaging and coatings for food and other products. It also shows how scientists are inspired by nature to create new materials that can solve real-world problems.

Key Facts

• A team of international researchers created a new foam-based material that appears white without any added pigment.
• The material was made using light and a mild solvent, which creates a porous structure that scatters light.
• This innovation could replace materials currently made with titanium dioxide and PFAS.
• The process is called Deep Foam Photolithography (DFP).
• The resulting materials platform can achieve ultrahigh resolution (20,000 DPI)

Key Terms

Structural Whiteness

A phenomenon where a material appears white due to the way its microscopic structure interacts with light.

Implications

This innovation could lead to safer packaging and coatings for food and other products. It also shows how scientists are inspired by nature to create new materials that can solve real-world problems.