Professor Easan Sivaniah of Kyoto University led an international engineering team that developed a porous polymer printing platform in 2026 to generate structural whiteness and fluid repellency without traditional industrial additives. The research, conducted at the Institute for Integrated Cell-Material Sciences alongside Tokyo Metropolitan University and Donghua University, was published in the journal Nature.
The system requires no pigments.
Elimination of regulated industrial chemical additives
Industrial manufacturers currently add titanium dioxide to white packaging, films, and opaque coatings, despite the European Union banning the compound as a food additive due to consumer safety concerns. Factories also apply per- and polyfluoroalkyl substances, known as PFAS, to coat consumer goods with water- and oil-resistant barriers. These persistent synthetic materials face worldwide regulatory restrictions because fluorinated chemical compounds accumulate indefinitely in natural ecosystems and human tissue.
To replace both components at once, the academic team designed microscopic pore arrays that scatter light like natural foams while forming a rough, water-shedding exterior layer inspired by the microscopic topography of lotus leaves. Tokyo Metropolitan University Associate Professor Taiki Yanagishima said: “A key challenge faced by biomimetic science is realizing environmentally friendly material designs inspired by nature at the scale and cost of existing materials.”
Dual functional results from photolithographic foam expansion
The manufacturing method, named Deep Foam Photolithography, exposes a selected polymer sheet to light before treating the irradiated substrate with a mild chemical solvent. Light initially breaks down the polymer chains into localized molecular fragments that interact directly with the liquid solvent, causing the internal structure of the base substance to swell into an open microscopic network capable of reflecting wavelengths across the visible spectrum with remarkable efficiency. This internal transformation creates bright optical opacity from light scattering while simultaneously building a rugged surface geometry that forces water droplets to roll off the exterior plane without chemical assistance. Optical whiteness mirrors the pigment-free physical structure seen in snow, sea waves, and the unprinted fibers of Japanese washi paper.
The technique eliminates secondary finishing steps.
Adaptation across commercial polymers and textile surfaces
Textile researchers at Donghua University in China tested the foaming process directly on commercial fabrics to evaluate performance outside conventional thin-film backings. Testing confirmed that the lithographic sequence alters the light scattering and water management of woven textiles without degrading the underlying fiber matrix. The fabrication pipeline avoids the synthesis of custom chemical compounds by utilizing polymers that are already commercially available in industrial supply chains.
Technical specifications established by the engineering group
- Print resolution reaches 20,000 DPI on compatible substrates.
- Optical opacity operates without titanium dioxide mineral particles.
- Surface water shedding functions without fluorinated PFAS coatings.
- Base material compatibility includes multiple commercial polymer types.
Engineers achieved an ultrahigh printing resolution of 20,000 DPI during laboratory trials with the light-driven patterning procedure. Sivaniah and his co-authors verified the physical mechanism through structural examination of the swollen polymer networks.
The study recorded its experimental framework under article number 10968.