In Situ Programmable, Active, and Interactive Crystallization by Localized Polymerization.

Additive manufacturing has sought active and interactive means of creating predictable structures with diverse materials. Compared to such active manufacturing tools, current crystallization strategies remain in statistical and passive programs of crystals via macroscale thermodynamic controllers, commonly lacking active means to intervene in crystal growth in a spatiotemporal manner. Herein, a strategy toward active and interactive programming and reprogramming of crystals, realized by real-time tangible feedback on growing crystals by delicately controlling the degree of in-situ, localized photopolymerization of polymeric structures via additive manufacturing is presented.

Hierarchically-structured ratchet skimmer with superhydrophilicity for continuous recovery of high-viscosity oil.

Oil spill accidents have series environmental and economic impacts, increasing the demand for efficient technologies to recover oil from contaminated waters. In this study, a hierarchically structured ratchet surface with superhydrophilicity was presented as a novel oil skimming mechanism for the recovery of high-viscosity oil, particularly low-sulfur fuel oil (LSFO), which has recently been used as marine fuel in open water environments. The interaction between the superhydrophilic ratchet and oil provides favorable conditions for oil retention at the water surface.

Capillary Skimming of Floating Microplastics via a Water-Bridged Ratchet.

Floating microplastics (MPs) have recently become a major concern in marine pollution; however, current filter-based technology is hardly effective for directly removing such MPs from the water surface because of specific mesh size and clogging issues. This paper introduces a new skimming concept for removing floating MPs utilizing capillary force mediated by the elevation of a hydrophilic ratchet at the air-water interface. MPs floating near the ratchet surface are spontaneously forced toward the ratchet with a concave water meniscus, driven by the Cheerios effect.

Development of rapid and effective oil-spill response system integrated with oil collection, recovery and storage devices for small oil spills at initial stage: From lab-scale study to field-scale test.

In the present study, through the laboratory-to-field scale experiments and trials, we report the development and evaluation of an integrated oil-spill response system capable of oil collection, recovery (separation), and storage, for a timely and effective response to the initial stage of oil-spill accidents. With the laboratory-scale experiments, first, we evaluate that the water-surface waves tend to abate the oil recovery rate below 80% (it is above 95% for the optimized configuration without the waves), which is overcome by installing the hydrophilic (and oleophobic) porous structures at the inlet and/or near the water outlet of the separator. In the follow-up meso-scale towing tank tests with a scaled-up prototype, (i) we optimize the maneuverability of the assembled system depending on the speed and existence of waves, and (ii) evaluate the oil recovery performance (more than 80% recovery for the olive oil and Bunker A fuel oil).

Self-Healable Conductive Hydrogels with High Stretchability and Ultralow Hysteresis for Soft Electronics.

Stretchable sensors based on conductive hydrogels have attracted considerable attention for wearable electronics. However, their practical applications have been limited by the low sensitivity, high hysteresis, and long response times of the hydrogels. In this study, we developed high-performance poly(vinyl alcohol) (PVA)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) based hydrogels post-treated with NaCl, which showed excellent mechanical properties, fast electrical response, and ultralow hysteresis properties.

Universal Stretchable Conductive Cellulose/PEDOT:PSS Hybrid Films for Low Hysteresis Multifunctional Stretchable Electronics.

Skin-attachable conductive materials have attracted significant attention for use in wearable devices and physiological monitoring applications. Soft, skin-like conductive films must have excellent mechanical and electrical characteristics with on-skin conformability, stretchability, and robustness to detect body motion and biological signals. In this study, a conductive, stretchable, hydro-biodegradable, and highly robust cellulose/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hybrid film is fabricated.

Multiscale landscaping of droplet wettability on fibrous layers of facial masks.

Liquid mobility is ubiquitous in nature, with droplets emerging at all size scales, and artificial surfaces have been designed to mimic such mobility over the past few decades. Meanwhile, millimeter-sized droplets are frequently used for wettability characterization, even with facial mask applications, although these applications have a droplet-size target range that spans from millimeters to aerosols measuring less than a few micrometers. Unlike large droplets, microdroplets can interact sensitively with the fibers they contact with and are prone to evaporation.

Dimensional Control of Highly Anisotropic and Transparent Conductive Coordination Polymers for Solution-Processable Large-Scale 2D Sheets.

Controlling the dimensional aspect of conductive coordination polymers is currently a key scientific interest. Herein, solution-based dimension control strategies are proposed for copper chloride thiourea (CuCl-TU) coordination polymers that enable centimeter-scale, 2D nanosheet formation for use as transparent electrodes. Despite the wide bandgap of CuCl-TU polymers (4.

Stretchable and Conductive Cellulose/Conductive Polymer Composite Films for On-Skin Strain Sensors.

Conductive composite materials have attracted considerable interest of researchers for application in stretchable sensors for wearable health monitoring. In this study, highly stretchable and conductive composite films based on carboxymethyl cellulose (CMC)-poly (3,4-ethylenedioxythiopehe):poly (styrenesulfonate) (PEDOT:PSS) (CMC-PEDOT:PSS) were fabricated. The composite films achieved excellent electrical and mechanical properties by optimizing the lab-synthesized PEDOT:PSS, dimethyl sulfoxide, and glycerol content in the CMC matrix.

Hygroscopic ramie fabrics for recovering highly viscous low sulfur fuel oil.

Low sulfur fuel oils (LSFOs) with less than 0.5% sulfur content have been mandated for marine vessels by the International Maritime Organization since 2020. However, owing to the low dispersibility and high viscosity of LSFOs, their oceanic spills are difficult to clean using conventional response systems.

Unclogged Janus Mesh for Fog Harvesting.

Janus membranes with asymmetric surface wettability have been extensively utilized in various fields, including fog harvesting, because of their novel liquid transport properties. However, Janus membranes have an inherent disadvantage in terms of aerodynamic efficiency in harvesting fog because of the clogged water bridges caused by the small pore size. In the present work, we applied Janus wettability to mesh geometry with systematically varying hole sizes.

Slippery, Water-Infused Membrane with Grooved Nanotrichomes for Lubricating-Induced Oil Repellency.

Water, abundant and ubiquitous in nature, is an easy yet powerful resource for the creatures to survive by putting together with their topologies interfacing their living environment. Here, a slippery, water-infusing surface (SWIS) that retains a thick and stable water layer on the membrane is presented, robustly maintaining the oil repellency against the pressure and friction of immiscible liquids. Inspired by the plant trichome structures and their function, grooved nanotrichome, formed on the fibrous membrane by the oxygen plasma etching, induces robust water lubrication on the SWIS.

Direct recovery of spilled oil using hierarchically porous oil scoop with capillary-induced anti-oil-fouling.

The pitcher plant has evolved its hierarchically grooved peristome to enhance a water-based slippery system for capturing insects with oil-covered footpads. Based on this, we proposed a hierarchically porous oil scoop (HPOS) with capillary-induced oil peel-off ability for repeatable spilled oil recovery. As the HPOS scoops oil-water mixture, water passes through the hole while the oil is confined within a curved geometry.

Clogged water bridges for fog harvesting.

Capillary water bridges clogged in the holes of mesh-type fog harvesters have previously been considered only as a drawback because they decrease fog-harvesting yield by hindering airflow in front of the clogged mesh in the usual wind conditions. In this study, we show that the role of a clogged water bridge may not be entirely negative and can contribute to increased fog harvesting by increasing the effective shade coefficient in a special condition with high fog inertia. As the fog speed close to the mesh or the plate increases, clogged mesh as well as the impermeable solid plate are found to produce high fog-harvesting efficiency owing to the high inertia of fog particles that impact the blocked wall.

Effect of crystallinity on the recovery rate of superhydrophobicity in plasma-nanostructured polymers.

This study explored the optimum conditions to achieve superhydrophobicity in polyethylene terephthalate (PET) in terms of crystallinity and microstructure. Surface superhydrophobicity was achieved by nanostructures induced by oxygen plasma etching and the recovery process of low surface energy through thermal aging of various PETs; semi-crystalline biaxial PET (B-PET) film, amorphous PET (A-PET) film, and semi-crystalline PET (F-PET) fabric. Under the anisotropic plasma etching, the nanostructures on the B-PET film were the longest, followed by the F-PET fabric, which developed a hierarchical micro/nanostructure, then the A-PET film.

Single-step plasma-induced hierarchical structures for tunable water adhesion.

Smart surfaces in nature have been extensively studied to identify their hierarchical structures in micro-/nanoscale to elucidate their superhydrophobicity with varying water adhesion. However, mimicking hybrid features in multiscale requires complex, multi-step processes. Here, we proposed a one-step process for the fabrication of hierarchical structures composed in micro-/nanoscales for superhydrophobic surfaces with tunable water adhesion.

Subwavelength Hollow-Nanopillared Glass with Gradient Refractive Index for Ultralow Diffuse Reflectance and Antifogging.

Nanostructured glass with subwavelength hollow nanopillars of diameters of sub-65 nm was fabricated, showing high optical transmittance and ultralow diffuse reflectance. A simple process involving single-step plasma etching was used on a glass slide coated with a SiO sacrificial film. First, SiO nanodot structures were formed using plasma-induced anisotropic etching with CF plasma.

Multiple air-bubble enhanced oil rupture on nanostructured cellulose fabric for easy-oil cleaning fouled in a dry state.

Nanostructured cellulose fabric with an air-bubble-enhanced anti-oil fouling property is introduced for quick oil-cleaning by water even with the surface fouled by oil before water contact under a dry state. It is very challenging to recover the super-hydrophilicity because once the surface is oil-fouled, it is hard to be re-wetted by water. Anti-oil-fouling under a dry state was realized through two main features of the nanostructured, porous fabric: a low solid fraction with high-aspect-ratio nanostructures significantly increasing the retracting forces, and trapped multiscale air bubbles increasing the buoyancy and backpressure for an oil-layer rupture.

Copper-Halide Polymer Nanowires as Versatile Supports for Single-Atom Catalysts.

Single-atom catalysts are heterogeneous catalysts with atomistically dispersed atoms acting as a catalytically active center, and have recently attracted much attention owing to the minimal use of noble metals. However, a scalable and inexpensive support that can stably anchor isolated atoms remains a challenge due to high surface energy. Here, copper-halide polymer nanowires with sub-nanometer pores are proposed as a versatile support for single-atom catalysts.

Plasma-Based Nanostructuring of Polymers: A Review.

There are various fabrication methods for synthesizing nanostructures, among which plasma-based technology is strongly competitive in terms of its flexibility and friendly uses, economy, and safety. This review systematically discusses plasma techniques and the detailed interactions of charged particles, radicals, and electrons with substrate materials of, in particular, polymers for their nanostructuring. Applications employing a plasma-based nanostructuring process are explored to show the advantages and benefits that plasma treatment brings to many topical and traditional issues, and are specifically related to wettability, healthcare, or energy researches.

Nanotexturing of Conjugated Polymers via One-Step Maskless Oxygen Plasma Etching for Enhanced Tunable Wettability.

A one-step maskless oxygen plasma etching process is investigated to nanopattern conjugated polymer dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)) and to examine the effects of nanostructures on the inherent tunable wettability of the surface and the droplet mobility. Etching characteristics such as the geometry and dimensions of the nanostructures are systematically examined for the etching power and duration. The mechanism of self-formation of vertically aligned dense-array pillared nanostructures in the one-step maskless oxygen plasma etching process is also investigated.

Spontaneous formation of aligned DNA nanowires by capillarity-induced skin folding.

Although DNA nanowires have proven useful as a template for fabricating functional nanomaterials and a platform for genetic analysis, their widespread use is still hindered because of limited control over the size, geometry, and alignment of the nanowires. Here, we document the capillarity-induced folding of an initially wrinkled surface and present an approach to the spontaneous formation of aligned DNA nanowires using a template whose surface morphology dynamically changes in response to liquid. In particular, we exploit the familiar wrinkling phenomenon that results from compression of a thin skin on a soft substrate.

UV-responsive nano-sponge for oil absorption and desorption.

Controlled surface wettability for oil has been intensively studied to remove industrial oil waste or oil spill pollution from seas or rivers. In particular, external stimuli-induced special wetting materials, such as photo-responsive TiO2, have attracted considerable attention for oil-water separation. In this study, a novel method is reported to fabricate a nano-sponge which is composed of hydrophobic hydrocarbon and hydrophilic TiO2 nanoparticles for oil absorption or desorption that are responsive to UV irradiation.

Extreme wettability of nanostructured glass fabricated by non-lithographic, anisotropic etching.

Functional glass surfaces with the properties of superhydrophobicity/or superhydrohydrophilicity, anti-condensation or low reflectance require nano- or micro-scale roughness, which is difficult to fabricate directly on glass surfaces. Here, we report a novel non-lithographic method for the fabrication of nanostructures on glass; this method introduces a sacrificial SiO2 layer for anisotropic plasma etching. The first step was to form nanopillars on SiO2 layer-coated glass by using preferential CF4 plasma etching.