Breathable Fabrics with Robust Superhydrophobicity via In Situ Formation of Hierarchical Surface Morphologies.

Superhydrophobic fabrics have recently attracted extensive interest not only in the fields of water-repellent clothing but also for the emerging functional fabrics due to their intrinsic flexibility and excellent stability. In this work, we proposed a simple, cost-effective, and environmentally friendly method to fabricate superhydrophobic fabrics with a broad application scope for textiles of different apertures. The flexible, breathable, and superhydrophobic fabric was realized via a three-step process, including polydimethylsiloxane (PDMS) encapsulation, in situ microcilia array formation, and silica nanoparticle decoration. With an adhesive PDMS layer and additive NdFeB particles, the hierarchical structures can tightly attach to the fabric substrate to provide robustness and durability. Specifically, the optimization of microcilia architecture was achieved via tuning the composite mass ratios so that suitable morphologies can be produced for robust nonwetting behavior. The superhydrophobic fabrics possess a contact angle and sliding angle of ∼155 and ∼3°, respectively, with excellent durability against 650 cycles' periodic mechanical abrasion, 130 cycles' tape-peeling test, washing evaluation, and chemical corrosions. Furthermore, the superhydrophobic fabric shows outstanding breathability and flexibility to be adaptive to surfaces with curvature or irregular shapes. The presented superhydrophobic strategy was considered to be feasible for multiple fabric substrates, revealing the broad application potential for fields of healthcare production, outdoor goods, catering industry, etc.

Structural and Optical Properties of Textured Silicon Substrates by Three-Step Chemical Etching.

We implemented the fabrication of hybrid structures, including pyramids, etching holes, and inverted pyramidal cavities on silicon substrates, by three-step chemical etching. To achieve this, we utilized anisotropic wet etching as the first-step etching to form pyramids of various sizes. Subsequently, metal-assisted chemical etching was performed to develop aligned etching holes on the pyramidal structure. Ultimately, anisotropic wet etching was used again as the third-step etching for the etchant to penetrate holes to form inverted pyramidal cavities. Optimizing the three-step etching treatments, large-scale textured structures with low reflectance could be obtained, and they show potential for applications in sensors, solar cells, photovoltaics, and surface-enhanced Raman scattering (SERS). Examples of using the textured silicon substrates for SERS applications were given.