A novel, single‐step and single‐component bio‐inspired fabrication method of hierarchical superoleophobic surfaces is presented. The method consists in thermal deposition of self‐assembling ultra‐low‐surface‐energy fluorinated wax on diverse surfaces. The thermal deposition results in crystalline, oriented, three‐dimensional hierarchical structures with high surface roughness and re‐entrant curvature, which in combination with the low surface energy of the fluorinated wax results in high contact angles of low‐surface‐tension liquids and low contact‐angle hysteresis (CAH) values (Δθ). The values achieved for Δθ are below 10° even for ethanol, which exhibits a surface tension as low as 22.4 mN·m−1. In addition to their superoleophobic properties our substrates exhibit extreme superhydrophobic qualities (CAH as low as 2° and contact angle >170°) with exceptional surface stability over many months. The proposed fabrication method may be utilized for a variety of applications where non‐wetting of low‐surface‐tension liquids is required, for example non‐staining surfaces and antifouling. The ease of fabrication and the variety of substrates that can be modified will undoubtedly widen its use.
Bulk metallic glasses (BMGs) have been developed as a means to achieve durable multiscale, nanotextured surfaces with desirable properties dictated by topography for a multitude of applications. One barrier to this achievement is the lack of a bridging technique between macroscale thermoplastic forming and nanoimprint lithography, which arises from the difficulty and cost of generating controlled nanostructures on complex geometries using conventional top-down approaches. This difficulty is compounded by the necessary destruction of any resulting reentrant structures during rigid demolding. We have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide (ZnO) nanostructures. It is established that such structures can be grown inexpensively and quickly with tunable morphologies on a wide variety of substrates out of solution, which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up approach. In this way, we achieve metallic structures that simultaneously demonstrate features from the macroscale down to the nanoscale, requiring only the top-down fabrication of macro/microstructured molds. Upon detachment of the formed part from the multiscale molds, the ZnO remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the BMGs nanoporous. The ability to pattern metallic surfaces in a single step on length scales from centimeters down to nanometers is a critical step toward fabricating devices with complex shapes that rely on multiscale topography for their intended functions, such as biomedical and electrochemical applications.
Atomic layer deposition (ALD) is widely used in science and technology, particularly in microelectronics, because it allows well-controlled production of highly conformal thin films. Technoindustrial advancements in microelectronics require more accurate guidance of deposition, as features in electronic devices keep shrinking. Therefore, improved lithographic capabilities are needed, and bottom-up, self-aligned methods of lithography have attracted much attention. In this context, step decoration has been extensively explored for some decades, but ALD was seldom, if ever, considered. Gaining a better fundamental understanding of such processes is an important milestone toward their practical implementation. Here, using trimethyl(methylcyclopentadienyl)platinum(IV), MeCpPtMe3, and O3 on terraced α-Al2O3 (sapphire) miscut surfaces, we demonstrate selective deposition of platinum particles deposited by ALD. An observed interconnection between the selectivity and the miscut angle of the surface was discussed and modeled. These results shed light on the role of low-coordination surface-sites on terraced surfaces in the guidance of deposition performed by ALD.
A single‐step and single‐component bioinspired method for the fabrication of hierarchical superoleophobic surfaces is presented by B. Pokroy and co‐workers . Fabrication via the thermal deposition of fluorinated wax results in crystalline, oriented, 3D hierarchical structures with high surface roughness and re‐entrant curvature. The surfaces exhibit superhydrophobic and superoleophobic qualities combined with exceptional stability, making them applicable to a wide range of fields.
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