Nature-Inspired Nanostructured Materials: From Super-Repellent Surfaces to Starfruit-like Silica Particles

Millions of years of evolution have perfected "synthetic" strategies in Nature that lead to superior materials and elegant structures, such as "self-cleaning" lotus leaves and exquisite siliceous cell wall of diatom. In this talk, I will discuss our recent attempts to obtain super-repellent surfaces and starfruit-like silica particles, by mimicking their naturally occurring counterparts.

The well-known self-cleaning property of the lotus leaf is due to a combination of proper chemistry and unique multilength-scale surface topology. We have successfully mimicked the dual-scale structure by incorporating raspberry-like silica particles to polymer films, which have been turned superhydrophobic. For practical applications, it is also highly desirable for superhydrophobic surfaces to be oil repellent; so we further examined the feasibility to achieve oil repellency on structured surfaces. By modifying multilength-scale structured surfaces with perfluoroalkyl chains, we successfully obtained (super) oil-repellent surfaces, including superoleophobic textiles.

By using a chitosan-phosphate complex as the soluble directing agent in biomimetic silicification, we obtained unique starfruit-like silica particles. CryoTEM and CryoET (electron tomography) confirmed the templating effect of chitosan in biosilicification: the chitosan-phosphate complex formed 3D starfruit-like aggregates, by which the starfruit-shaped silica particles were directed to form.