Researchers successfully design materials with extremely low ice adhesion.

Patterned surfaces: The fabrication of patterned superomniphobic–superomniphilic surfaces is reported. Such patterned surfaces are expected to be useful in developing well‐defined microreactors for liquid‐phase reactions, significantly enhancing heat transfer during condensation and boiling of various low‐surface‐tension liquids, and in fabricating precisely tailored arrays of polymers and microparticles of different sizes and shapes.

and HL/OL (omniphilic, all liquids wetting), [ 4 ] have a large number of applications including chemical and biological protection, oil-water separation, stain-resistant textiles, "non-stick" coatings, controlling protein and cell adhesion on surfaces, reduction of biofouling, and enhanced heat transport. However, there is no established technique that allows for selectively generating and patterning all four extreme wettabilities [ 5 ] on a single surface, especially at the length scale necessary for microfl uidic control. In this work, we discuss a facile methodology for the fabrication of surfaces with extreme wettabilities by selectively modifying the surface energy and roughness of different paper surfaces.Paper has recently emerged as a promising materials platform for microfl uidic devices due to its low cost, easy disposal, high surface area, capillary-based wetting, fl exibility, and compatibility with a wide range of patterning and printing techniques. [ 6 ] Since the fi rst report of using paper as a base material in microfl uidics by Whitesides et al. in 2007, [ 7 ] a new era of paper-based microfl uidic devices has arisen. [ 8 ] The ability to pattern wetting/non-wetting channels on paper has allowed multiplexed, small-volume fl uid control both in 2D lateral fl ow on a single surface [ 9 ] and 3D fl ow on stacked layers connected through pores. [ 10 ] Generally, fl uidic channels introduced on paper surfaces are composed of wettable domains bounded by non-wettable domains, or by air gaps. [ 11 ] In most cases, paper-based microfl uidic channels have been developed to contain only water or aqueous solutions. [ 12 ] Few reported techniques used for generating patterned wettability on paper result in devices compatible with even a limited number of non-aqueous liquids. [ 13 ] Further, the wettable channels in the paper-based microfl uidic systems reported thus far show no selective wettability with liquids possessing different surface tensions and/or polarities. In other words, all liquids wet these fl uidic channels. Overall, there is no established technique that allows for the selective generation of all four "extreme wettabilities" [ 5 ] on paper-based microfl uidic channels; that is, the four possible combinations of wetting of oil (oleophilic -OL or oleophobic-OP) and water (hydrophilic-HL and hydrophobic-HP) on a surface. The four extreme wettabilities are: HP/OP (omniphobic, all liquids non-wetting), [ 1 ] HP/OL (water nonwetting, oil wetting), [ 2 ] HL/OP (water wetting, oil

Precise control over the geometry and chemistry of multiphasic particles is of significant importance for a wide range of applications. In this work, we have developed one of the simplest methodologies for fabricating monodisperse, multiphasic micro- and nanoparticles possessing almost any composition, projected shape, modulus, and dimensions as small as 25 nm. The synthesis methodology involves the fabrication of a nonwettable surface patterned with monodisperse, wettable domains of different sizes and shapes. When such patterned templates are dip-coated with polymer solutions or particle dispersions, the liquids, and consequently the polymer or the particles, preferentially self-assemble within the wettable domains. Utilizing this phenomenon, we fabricate multiphasic assemblies with precisely controlled geometry and composition through multiple, layered depositions of polymers and/or particles within the patterned domains. Upon releasing these multiphasic assemblies from the template using a sacrificial layer, we obtain multiphasic particles. The templates can then be readily reused (over 20 times in our experiments) for fabricating a new batch of particles, enabling a rapid, inexpensive, and easily reproducible method for large-scale manufacturing of multiphasic particles.

Intelligente Oberflächen: Strukturierte superomniphobe und superomniphile Oberflächen wurden hergestellt. Die möglichen Anwendungen dieser Oberflächen sind vielfältig, z. B. für Mikroreaktoren zur Verbesserung des Wärmetransfers beim Kondensieren und Sieden von Flüssigkeiten mit niedriger Oberflächenspannung und zur Herstellung von maßgeschneiderten Polymerarrays und Mikropartikeln unterschiedlicher Größe und Form.

Fabrication of charged, multiphasic, polymeric microand nanoparticles with precise control over their composition, size, and shape is critical for developing the next generation of drug carriers for combinatorial therapies and theranostics. The addition of charged polyelectrolyte multilayers on the surface of polymeric particles can significantly improve their stability, targeting efficacy, drug-release kinetics, and their ability to encapsulate different drugs within a single particle. Many of the traditional methods for multilayer functionalization of multiphasic polymeric particles are time and energy intensive which significantly limits their scalability, and therefore therapeutic potential. In this work, we combine the bulk layer-by-layer polyelectrolyte application methodology with our previously developed technique of fabricating multiphasic polymeric particles on substrates with patterned wettability to synthesize biocompatible, monodisperse, Janus polymer−polyelectrolyte particles.

We fabricated ultra‐high aspect ratio silicon nanomaterials, including a silicon nanomesh and silicon nanowire array, on a wafer scale for efficient photoelectrochemical hydrogen production. These silicon nanomaterials (feature size≈20 nm) possess a high aspect ratio to increase the optical absorptivity of the cells to approximately 95 % over a broad range of wavelengths. The silicon nanomesh and Si nanowire cells achieved high photocurrent values of 13 and 28 mA cm−2, respectively, which are increased by 200 % and 570 % in comparison to their bulk counterparts. In addition, these scalable Si nanomaterials remained stable for up to 100 min of hydrogen evolution. Detailed studies on the doping and geometrical structures of the resulting hydrogen evolution cells suggest that both the n+ pp+ doping and thickness of nanostructures are keys to the enhancement of the hydrogen evolution efficiency. The results obtained in this work show that these silicon nanomaterials can be used for high‐performance water‐splitting system applications.

Hydrogen from the Sun: The cover image illustrates Si nanowire arrays with ultra‐high aspect ratios for the application of photoelectrochemical hydrogen evolution. As described in the Full Paper by Duck Hyun Lee and colleagues at the University of Michigan and Silicium Energy on the authors have created such wafer‐scale nanowire arrays using the combination of block copolymer lithography and metal‐assisted etching. Thus, the fabrication of the Si nanowire cells was performed using scalable manufacturing techniques, and they exhibited high absorbance of incident light, a reduced minority carrier transport distance, and a high chemical reaction surface area. These structural advantages of the Si nanomaterials developed here enabled us to achieve remarkably high photocurrents and hydrogen evolution efficiencies.