Dr. Shichao Niu, Pro. Zhiwu Han and their co-workers from Jilin University (P. R. China) made a significant breakthrough in the bionic surface field. They designed and fabricated a kind of monolayer SiO2 film based on a glass substrate with excellent active antifogging properties, and published their work on ACS Nano.

Fog formation on transparent surfaces is ubiquitous and constitutes a hindrance for optical devices requiring high light transmission, such as eyeglasses, automobile windshields, solar cells, laparoscopes and so on. Therefore, antifogging surfaces with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, a major challenge remains in achieving high-speed antifogging performance and revealing its hydrophilic-based antifogging mechanism of glass or other transparent materials under aggressive fogging conditions.

In this work, with inspiration from the fog-free properties of the typical Morpho menelaus terrestris butterfly (Butler, 1866) wing scales, a novel monolayer SiO2 film with multiscale hierarchical pagoda structures (MHPSs) based on a glass substrate was designed and fabricated using a facile but effective biotemplate method without any post-treatments. The biomimetic monolayer film (BMF) with MHPSs displayed excellent antifogging properties, which even kept high transmittance (~95%) under aggressive fog conditions. Interestingly, it can rapidly recover to the initial fog-free state within several seconds (<5 s). More importantly, the underlying active antifogging strategy gathering together the initial fog capture and final anisotropic spread was revealed. High-speed active antifogging performance of the bioinspired structural surface enabled the retention of a high transmittance property, heralding the reliable optical performance in outdoor practical applications, especially in aggressive foggy environments.

The reported work offers a promising way to handily design and fabricate bioinspired artificial surfaces with multiscale hierarchical structures that possess high-performance physicochemical properties.

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