Researchers create pigment-free white polymers for future packaging

Researchers at Kyoto University have developed a new technology that creates highly white polymer materials through the internal structure of the material itself, potentially reducing the need for conventional pigments and fluorinated coatings in packaging applications.

The technology, called Deep Foam Photolithography (DFP), creates a porous polymer structure that scatters light, producing intense whiteness while also providing water-repellent surface properties.

Unlike conventional approaches that rely on additives such as titanium dioxide, the method modifies the physical structure of the polymer to achieve the desired optical and surface characteristics.

Structural whiteness replaces added pigments

Most white packaging plastics rely on pigments, with titanium dioxide being one of the most widely used materials to create opacity and brightness.

The Kyoto University researchers took inspiration from natural materials where whiteness is created by microscopic structures that scatter incoming light.

Using DFP, light and a mild solvent induce changes within the polymer, causing it to swell and form an open porous structure.

The resulting microstructure scatters light strongly, creating what researchers describe as structural whiteness.

Technology also creates water-repellent surfaces

Beyond optical performance, the porous structure produces a rough surface similar to the water-repellent effect observed on lotus leaves.

This creates hydrophobic properties without requiring additional fluorinated coatings.

The combination of whiteness and water repellency could be particularly interesting for packaging applications where appearance, moisture resistance and surface functionality are required simultaneously.

PET applications could accelerate commercial relevance

The researchers have demonstrated the DFP process in several polymers, including PET, polystyrene, polycarbonate, cellulose triacetate, polysulfone and polymethyl methacrylate.

PET is particularly relevant for packaging because it is already widely used in bottles, films and other commercial formats.

The team is now interested in exploring other packaging polymers such as polyethylene and polypropylene, although these materials have not yet been demonstrated with the process.

Alternative to titanium dioxide requires further validation

The research team suggests that DFP could eventually provide an alternative route to achieving white packaging without titanium dioxide additives.

However, the researchers acknowledge that titanium dioxide remains a highly effective pigment and that direct comparisons under realistic packaging conditions are still required.

Future studies will need to evaluate optical performance, durability, processing compatibility and behaviour during recycling.

PFAS-free functionality attracts packaging interest

The ability to create water resistance through polymer structure rather than chemical coatings could also be relevant as industries reduce their dependence on PFAS-based treatments.

PFAS compounds have historically been used to provide water and grease resistance in several packaging applications, but increasing regulatory restrictions are driving the search for alternatives.

DFP offers a different approach by changing the physical architecture of the material rather than adding a separate functional layer.

Commercial packaging applications remain under development

Potential applications include flexible films, labels, surface coatings and eventually moulded packaging components.

However, moving from laboratory samples to industrial packaging will require further optimisation, including compatibility with existing manufacturing processes and assessment of end-of-life performance.

The researchers are now seeking partnerships with packaging companies to evaluate the technology on real products.

New material strategies rethink packaging functionality

The development reflects a broader trend in packaging materials: achieving functionality through material architecture rather than through additional additives or complex structures.

If scaled successfully, technologies such as DFP could help create packaging materials that combine visual performance, water resistance and reduced chemical complexity.

The next challenge will be demonstrating that these advanced material structures can deliver the same benefits at commercial production scale while remaining compatible with circular packaging systems.