Porous Transition of Polyelectrolyte Film through Reaction-Induced Phase Separation Caused by Interaction with Specific Metal Ions

We describe a novel method for the simple and eco-friendly fabrication of porous polyelectrolyte films. A polyelectrolyte with many amine groups undergoes structural transformation from a dense to a porous structure upon immersion in a specific metal ion solution. The porous transition was the result of a reaction-induced phase separation, which was caused by the formation of new bonds between the polyelectrolyte and metal ions. This method enables control of the pore size of the porous structure in the nanoscale (54 nm) to microscale (1.63 μm) range through variation of the concentration or type of metal ions in the solution. To the best of our knowledge, this is the first report illustrating wide-range control of the pore size of a porous polyelectrolyte structure achieved by metal ions. These porous polyelectrolyte films with adjustable pore size and metastable metal ions can be employed in applications such as adsorption and catalysis

Bioinspired Hand-Operated Smart-Wetting Systems Using Smooth Liquid Coatings

Manually controllable “hand-operated” smart systems have been developed in many fields, including smart wetting materials, electronic devices, molecular machines, and drug delivery systems. Because complex morphological or chemical control are generally required, versatile strategies for constructing the system are technologically important. Inspired by the natural phenomenon of raindrops rarely bouncing and usually spreading on a puddle, we introduce a droplet-impact-triggering smart-wetting system using “non-smart” smooth liquid coating materials. Changing the droplet impact energy by changing the volume or casting height causes the droplet to completely bounce or spread on the liquid surface, regardless of the miscibility between the two liquids, owing to the stability of air layer. As the bouncing of a droplet on a liquid interface is not usually observed during wetting, we first analyze how the droplet bounces, then prove that the wettability is triggered by the droplet’s impact energy, and finally introduce some applications using this system

A Fluorine-free Slippery Surface with Hot Water Repellency and Improved Stability against Boiling

Inspired by natural living things such as lotus leaves and pitcher plants, researchers have developed many excellent antifouling coatings. In particular, hot-water-repellent surfaces have received much attention in recent years because of their wide range of applications. However, coatings with stability against boiling in hot water have not been achieved yet. Long-chain perfluorinated materials, which are often used for liquid-repellent coatings owing to their low surface energy, hinder the potential application of antifouling coatings in food containers. Herein, we design a fluorine-free slippery surface that immobilizes a biocompatible lubricant layer on a phenyl-group-modified smooth solid surface through OH−π interactions. The smooth base layer was fabricated by modification of phenyltriethoxysilane through a sol–gel method. The π-electrons of the phenyl groups interact with the carboxyl group of the oleic acid used as a lubricant, which facilitates immobilization on the base layer. Water droplets slid off the surface in the temperature range from 20 to 80 °C at very low sliding angles (<2°). Furthermore, we increased the π-electron density in the base layer to strengthen the OH−π interactions, which improved long-term boiling stability under hot water. We believe that this surface will be applied in fields in which the practical use of antifouling coatings is desirable, such as food containers, drink cans, and glassware

Controllable Broadband Optical Transparency and Wettability Switching of Temperature-Activated Solid/Liquid-Infused Nanofibrous Membranes

Inspired by biointerfaces, such as the surfaces of lotus leaves and pitcher plants, researchers have developed innovative strategies for controlling surface wettability and transparency. In particular, great success has been achieved in obtaining low adhesion and high transmittance <i>via</i> the introduction of a liquid layer to form liquid-infused surfaces. Furthermore, smart surfaces that can change their surface properties according to external stimuli have recently attracted substantial interest. As some of the best-performing smart surface materials, slippery liquid-infused porous surfaces (SLIPSs), which are super-repellent, demonstrate the successful achievement of switchable adhesion and tunable transparency that can be controlled by a graded mechanical stimulus. However, despite considerable efforts, producing temperature-responsive, super-repellent surfaces at ambient temperature and pressure remains difficult because of the use of nonreactive lubricant oil as a building block in previously investigated repellent surfaces. Therefore, the present study focused on developing multifunctional materials that dynamically adapt to temperature changes. Here, we demonstrate temperature-activated solidifiable/liquid paraffin-infused porous surfaces (TA-SLIPSs) whose transparency and control of water droplet movement at room temperature can be simultaneously controlled. The solidification of the paraffin changes the surface morphology and the size of the light-transmission inhibitor in the lubricant layer; as a result, the control over the droplet movement and the light transmittance at different temperatures is dependent on the solidifiable/liquid paraffin mixing ratio. Further study of such temperature-responsive, multifunctional systems would be valuable for antifouling applications and the development of surfaces with tunable optical transparency for innovative medical applications, intelligent windows, and other devices

Liquid-Infused Smooth Surface for Improved Condensation Heat Transfer

Control of vapor condensation properties is a promising approach to manage a crucial part of energy infrastructure conditions. Heat transfer by vapor condensation on superhydrophobic coatings has garnered attention, because dropwise condensation on superhydrophobic surfaces with rough structures leads to favorable heat-transfer performance. However, pinned condensed water droplets within the rough structure and a high thermodynamic energy barrier for nucleation of superhydrophobic surfaces limit their heat-transfer increase. Recently, slippery liquid-infused surfaces (SLIPS) have been investigated, because of their high water sliding ability and surface smoothness originating from the liquid layer. However, even on SLIPS, condensed water droplets are eventually pinned to degrade their heat-transfer properties after extended use, because the rough base layer is exposed as infused liquid is lost. Herein, we report a liquid-infused smooth surface named “SPLASH” (surface with π electron interaction liquid adsorption, smoothness, and hydrophobicity) to overcome the problems derived from the rough structures in previous approaches to obtain stable, high heat-transfer performance. The SPLASH displayed a maximum condensation heat-transfer coefficient that was 175% higher than that of an uncoated substrate. The SPLASH also showed higher heat-transfer performance and more stable dropwise condensation than superhydrophobic surfaces and SLIPS from the viewpoints of condensed water droplet mobility and the thermodynamic energy barrier for nucleation. The effects of liquid-infused surface roughness and liquid viscosity on condensation heat transfer were investigated to compare heat-transfer performance. This research will aid industrial applications using vapor condensation

Droplet Motion Control on Dynamically Hydrophobic Patterned Surfaces as Multifunctional Liquid Manipulators

In this letter, we introduce a novel liquid manipulation strategy to design dynamically hydrophobic and statically hydrophobic/hydrophilic patterned surfaces using an “omniphobicity”-based technique. The surfaces guide the sliding direction of a droplet in the presence of a statically hydrophilic area where the droplet does not stick on the transport path significantly enhancing the fluidic system transport efficiency. The concept of dynamically hydrophobic and statically hydrophobic/hydrophilic patterned surfaces in conjunction with omniphobic patterning techniques having surface multifunctionality, we believe, has potential not only for fluidic applications but also for future material engineering development

Discovery of Novel Selective Acetyl-CoA Carboxylase (ACC) 1 Inhibitors

We initiated our structure–activity relationship (SAR) studies for selective ACC1 inhibitors from <b>1a</b> as a lead compound. SAR studies of bicyclic scaffolds revealed many potent and selective ACC1 inhibitors represented by <b>1f</b>; however most of them had physicochemical issues, particularly low aqueous solubility and potent CYP inhibition. To address these two issues and improve the druglikeness of this chemical series, we converted the bicyclic scaffold into a monocyclic framework. Ultimately, this lead us to discover a novel monocyclic derivative <b>1q</b> as a selective ACC1 inhibitor, which showed highly potent and selective ACC1 inhibition as well as acceptable solubility and CYP inhibition profiles. Since compound <b>1q</b> displayed favorable bioavailability in mouse cassette dosing testing, we conducted in vivo PD studies of this compound. Oral administration of <b>1q</b> significantly reduced the concentration of malonyl-CoA in HCT-116 xenograft tumors at doses of more than 30 mg/kg. Accordingly, our novel series of selective ACC1 inhibitors represents a set of useful orally available research tools, as well as potential therapeutic agents for cancer and fatty acid related diseases