Biomimetic foaming photopolymers offer new waterproof, white material

Commercially available polymers have been used to create a foaming material that is bright white with no pigments and yet is still rigid. The photopolymer also has lotus-leaf like super-hydrophobicity, which could find application in replacing harmful fluorinated compounds in waterproof clothing and other products.

Drawing inspiration from nature and its range of structural colours that reflect light owing to their nanostructure, the team from Kyoto University’s iCeMS in Japan induced foaming of polymer films via UV-generated free radicals combined with a weak solvent. With light helping break the polymer into smaller molecular fragments, the solvent triggers pore nucleation and expansion. In what the researchers describe as a ‘controllable viscoelastic collapse’, the material is engineered to reveal ‘microflowers’, which provide a rough water-repellent outer surface around an internal network of pores that scatter light like snow, sea spray or clouds.