Pneumatic actuators are of great interest for device miniaturization, microactuators, soft robots, biomedical engineering, and complex control systems. Recently, multi-material actuators have become of high interest to researchers due to their comprehensive range of suitable applications. Three-dimensional (3D) printing of multi-material pneumatic actuators would be the ideal way to fabricate customized actuators, but so far, this is mostly limited to deposition-based methodologies, such as fused deposition modeling (FDM) or Polyjetting. Vat-based stereolithography is one of the most relevant high-resolution 3D printing methods but is only rarely utilized in the multi-material 3D printing of materials. This study demonstrated multi-material stereolithography using combinations of materials with different Young’s moduli, i.e., 0.5 MPa and 1.1 GPa, for manufacturing pneumatic actuators and microactuators with a resolution as small as 200 μm. These multi-material actuators have advantages over single-material actuators in terms of their deformation controllability and ease of assembly.
leaf (Nelumbo), superhydrophobic surfaces with a contact angle > 150° and low roll-off angles < 10°, have shown remarkable properties such as selfcleaning (so-called lotus effect), [1,2] antibiofouling [3] and anti-corrosion. [10,11] The surfaces rely on air pockets trapped in the micro-/nano-hierarchical structures to diminish the contact between the surface and the liquid to be repelled (Cassie-Baxter state). However, the composite solid/air interface design of these surfaces is metastable. Extreme conditions such as high pressure, high temperature, and abrasion cause loss of the super repellent properties, when the air is removed from the textured surfaces. Slippery liquid-infused porous surfaces (SLIPS) were developed as an alternative to superhydrophobic surfaces to address these limitations. [12][13][14] The mobility of the lubricant that is infused into the micro-/nanoporous structures allows liquid drops on the surface to easily slide off. These surfaces have shown exceptional omniphobicity, self-healing, [12] selfcleaning, [15] and antifouling properties. [15] However, like the air layer in superhydrophobic surfaces, the lubricant layer can be removed either by evaporation or replacement with other liquids and once the lubrication layer is lost and the solid surface is exposed, the material loses its slippery properties.Liquid repellent surfaces are of high interest in various fields like protective coatings and droplet manipulation due to their outstanding properties from self-cleaning to anti-fouling. Most reported surfaces rely on the fabrication of micro/-nanostructured surfaces, the infusion of porous surfaces with immiscible lubricants, or the grafting of monolayers with low surface energy to achieve repellence of various liquids. However, these methods are limited in terms of their durability and long-term stability. Here, the fabrication of smooth, transparent fluorinated poly (perfluoroalkyl methacrylate) coatings via UV-initiated radical polymerization in a simple one-step procedure is reported. The resulting surfaces show very low surface energies of down to 7 mN m −1 , low contact angle hysteresis below 5°, very good repellence towards various liquids with different polarities as well as self-cleaning and anti-graffiti ability. The fabricated coatings can be applied to various substrates from glass slides to microfiber cloths. This demonstrates that they outperform common commercially available fluorinated coatings, such as, for example, Hyflon AD 40L S, in terms of liquid repellence and their performance in real-world applications.
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