Functionalized Polyurethane-Coated Fabric with High Breathability,Durability, Reusability,and Protection Ability

Transmission of pathogens via respiratory droplets can spread infections such as COVID-19. Wearing a mask hinders the spread of COVID-19 infection and has become mandatory in some cases. Although most masks are affordable and disposable, continual daily replacement is required due to their performance deterioration caused by washing and contamination. Hence, a urethane-reactive coating material comprising perfluoro-tert-butanol-hexamethylene diisocyanate is developed with highly hydrophobic and oleophobic properties to functionalize a polyurethane-coated fabric to bestow high breathability, durability, reusability, and protection ability. Its functions are maintained after scratch and wash testing, and its air permeability and water vapor transmittance rate (necessary for respiration) are unaffected. Its filtration efficiency of water droplets containing 100 nm polystyrene particles (similar in size to SARS-CoV-2) is increased due to its highly hydrophobic properties. In addition, it inhibits the adsorption of bovine serum albumin, the spike protein of COVID-19, and Staphylococcus aureus and Pseudomonas aeruginosa.     

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

Poly(3‐hexyl thiophene) (P3HT) is widely regarded as the benchmark polymer when studying the physics of conjugated polymers used in organic electronic devices. P3HT can self‐assemble via π–π stacking of its backbone, leading to an assembly and growth of P3HT fibrils into 3D percolating organogels. These structures are capable of bridging the electrodes, providing multiple pathways for charge transport throughout the active layer. Here, a novel set of conditions is identified and discussed for P3HT organogel network formation via spin coating by monitoring the spin‐coating process from various solvents. The development of organogel formation is detected by in situ static light scattering, which measures both the thinning rate by reflectance and structural development in the film via off‐specular scattering during film formation. Optical microscopy and thermal annealing experiments provide ex situ confirmation of organogel fabrication. The role of solution characteristics, including solvent boiling point, P3HT solubility, and initial P3HT solution concentration on organogel formation, is examined to correlate these parameters to the rate of film formation, organogel‐onset concentration, and overall network size. The correlation of film properties to the fabrication parameters is also analyzed within the context of the hole mobility and density‐of‐states measured by impedance spectroscopy.     

Transparent Polymer-Ceramic Hybrid Antifouling Coating with Superior Mechanical Properties

Antifouling coatings are often required to have both excellent fouling resistance and mechanical properties for their applications. This study reports a water-borne antifouling coating consisting of an amine-terminated hyperbranched polysiloxane and a fouling resistant epoxy-zirconium particle, where the former is prepared using amine-functionalized silanes, and the latter is prepared via the reaction of zirconium alkoxide with epoxy-functionalized silanes and zwitterionic silanes. Such a hybrid coating is transparent (>99.5% transmittance) and exhibits a combination of polymeric and ceramic characteristics, namely, it has not only high hardness (7–9 H) and adhesion (≈3 MPa) to substrates but also good flexibility (≤10 mm bending diameter). The presence of the zwitterionic group allows the coating to have excellent oil repellency and fouling resistance. The effects of composition and structure on the mechanical properties and antifouling performance are investigated. This study aims to develop antifouling coatings to be used in foldable displays, optical sensors, and biomedical facilities.     

Carbon‐Nanotube–PDMS Composite Coatings on Optical Fibers for All‐Optical Ultrasound Imaging

Polymer–carbon nanotube composite coatings have properties that are desirable for a wide range of applications. However, fabrication of these coatings onto submillimeter structures with the efficient use of nanotubes has been challenging. Polydimethylsiloxane (PDMS)–carbon nanotube composite coatings are of particular interest for optical ultrasound transmission, which shows promise for biomedical imaging and therapeutic applications. In this study, methods for fabricating composite coatings comprising PDMS and multiwalled carbon nanotubes (MWCNTs) with submicrometer thickness are developed and used to coat the distal ends of optical fibers. These methods include creating a MWCNT organogel using two solvents, dip coating of this organogel, and subsequent overcoating with PDMS. These coated fibers are used as all‐optical ultrasound transmitters that achieve high ultrasound pressures (up to 21.5 MPa peak‐to‐peak) and broad frequency bandwidths (up to 39.8 MHz). Their clinical potential is demonstrated with all‐optical pulse‐echo ultrasound imaging of an aorta. The fabrication methods in this paper allow for the creation of thin, uniform carbon nanotube composites on miniature or temperature‐sensitive surfaces, to enable a wide range of advanced sensing capabilities.     

Controllable Underwater Oil‐Adhesion‐Interface Films Assembled from Nonspherical Particles

A controllable underwater oil‐adhesion‐interface is presented based on colloidal crystals assembled from nonspherical latex particles. The underwater oil‐adhesive force of the as‐prepared film can be effectively controlled from high to low adhesion by varying the latex structures from spherical or cauliflower‐like to single cavity, which effectively adjusts the solid/liquid contact mode/wetting state of oil droplets on the films. This facile fabrication of functional films with special underwater oil‐adhesion properties based on a flexible design of a latex structure will offer significant insight for the design and creation of novel underwater antifouling materials.     

Recent Developments and Practical Feasibility of Polymer‐Based Antifouling Coatings

While nature has optimized its antifouling strategies over millions of years, synthetic antifouling coatings have not yet reached technological maturity. For an antifouling coating to become technically feasible, it should fulfill many requirements: high effectiveness, long‐term stability, durability, ecofriendliness, large‐scale applicability, and more. It is therefore not surprising that the search for the perfect antifouling coating has been going on for decades. With the discovery of metal‐based antifouling paints in the 1970s, fouling was thought to be a problem of the past, yet its untargeted toxicity led to serious ecological concern, and its use became prohibited. As a response, research shifted focus toward a biocompatible alternative: polymer‐based antifouling coatings. This has resulted in numerous advanced and innovative antifouling strategies, including fouling‐resistant, fouling‐release, and fouling‐degrading coatings. Here, these novel and exciting discoveries are highlighted while simultaneously assessing their antifouling performance and practical feasibility.     

Stable Omniphobic Anisotropic Covalently Grafted Slippery Surfaces for Directional Transportation of Drops and Bubbles

Directional transportation and collection of liquids and bubbles are highly desirable in human life and industrial production. As one of the most promising types of functional surfaces, the reported anisotropic slippery liquid‐infused porous surfaces (SLIPSs) demonstrate unique advantages in liquid directional transportation. However, anisotropic SLIPSs readily suffer from the depletion of lubricant when used to manipulate droplets and bubbles, which leads to unstable surface properties. Therefore, fabricating stable anisotropic slippery surfaces for the directional transportation of drops and bubbles remains a challenge. Here, stable anisotropic covalently grafted slippery surfaces are fabricated by grafting polydimethylsiloxane molecular brushes onto directional microgrooved surfaces. The fabricated surfaces show remarkable anisotropic omniphobic sliding behaviors towards droplets with different surface tensions ranging from 72.8 to 37.7 mN m^?1 in air and towards bubbles underwater. Impressively, the surface maintains outstanding stability for the transportation of droplets (in air) and air bubbles (underwater) even after 240 d. Furthermore, anisotropic self‐cleaning towards various dust particles in air and directional bubble collection underwater are achieved on this surface. This stable anisotropic slippery surface has great potential for applications in the directional transportation of liquids and bubbles, microfluidic devices, directional drag reduction, directional antifouling, and beyond.     

Microfluidics for Rapid Detection of Live Pathogens

Rapid, sensitive, and selective detection of live pathogens remains a key priority for quality control and risk assessment. While conventional methods often require complicated workflows, costly reagents, lab equipment, and are time-consuming, rendering them inadequate for field testing and low-resource settings. Increased attention has been drawn to developing alternative low-cost and rapid methods to detect on-site live pathogens in different environmental matrices. Among them, microfluidic devices that integrate various laboratory functions in a miniaturized manner have proven to be a promising tool for the rapid and sensitive detection of pathogens. Herein, the development of microfluidic devices specifically designed for the detection of live pathogens is discussed along a concise summary of novel microfluidics systems recently developed, contrasted to conventional methods regarding assay time, the limit of detection, and target organisms. These include a variety of micro total analysis systems (µTAS) and microfluidic paper-based analytical devices (µPADs) in combination with molecular methods and traditional live cell detection techniques, such as cell culture, DNA intercalating dyes, resazurin, and immobilized bioreceptors (e.g., aptamers and capture antibodies). Furthermore, insights on the future perspectives of microfluidics for live pathogen detection with a highlight on the rapid and low-cost method development for field testing are provided.     

Nacre-Inspired Metal-Organic Framework Coatings Reinforced by Multiscale Hierarchical Cross-linking for Integrated Antifouling and Anti-Microbial Corrosion

A long-standing quest in marine materials science has been the development of tough and effective antifouling coatings for diverse surface protection. However, most commercial coatings are severely limited by poor mechanical behavior and unsustainable passive biocidal effect, leading to irreversible marine biofouling and even microbiologically influenced corrosion (MIC). Herein, inspired by the amorphous/crystalline feature within nacreous platelets, a mechanically robust antifouling coating composed of biopolymer-based hydrogel and dense metal-organic frameworks (MOFs) is developed. Tailoring the cross-linked networks across multiscale interfaces can furnish strength, dissipate strain, and improve toughness of the building blocks, resulting in a firm and scalable configuration on various substrates regardless of material category and surface topology. The resultant coating as a suitable reservoir exhibits a unique active defensive behavior of intelligent MOF degradation or drug release, enabling a groundbreaking performance for broad-spectrum biofouling and corrosion control. Notably, neither attachment of marine organisms nor MIC of metal substrates is observed and aggravated during the prolonged testing process in complex biological environments. This study provides distinctive insights into the underlying multimechanisms of comprehensive anti-fouling-corrosion and pioneer a rational strategy to design next-generation reliable MOFs-derived coatings in marine environments.     

Self‐Defensive Biomaterial Coating Against Bacteria and Yeasts: Polysaccharide Multilayer Film with Embedded Antimicrobial Peptide

Prevention of pathogen colonization of medical implants is a major medical and financial issue since infection by microorganisms constitutes one of the most serious complications after surgery or critical care. Immobilization of antimicrobial molecules on biomaterials surfaces is an efficient approach to prevent biofilm formation. Herein, the first self‐defensive coating against both bacteria and yeasts is reported, where the release of the antimicrobial peptide is triggered by enzymatic degradation of the film due to the pathogens themselves. Biocompatible and biodegradable polysaccharide multilayer films based on functionalized hyaluronic acid by cateslytin (CTL), an endogenous host‐defensive antimicrobial peptide, and chitosan (HA‐CTL‐C/CHI) are deposited on a planar surface with the aim of designing both antibacterial and antifungal coating. After 24 h of incubation, HA‐CTL‐C/CHI films fully inhibit the development of Gram‐positive Staphylococcus aureus bacteria and Candida albicans yeasts, which are common and virulent pathogens agents encountered in care‐associated diseases. Hyaluronidase, secreted by the pathogens, leads to the film degradation and the antimicrobial action of the peptide. Furthermore, the limited fibroblasts adhesion, without cytotoxicity, on HA‐CTL‐C/CHI films highlights a medically relevant application to prevent infections on catheters or tracheal tubes where fibrous tissue encapsulation is undesirable.     

Inherently UV Photodegradable Poly(methacrylate) Gels

Organogels (hydrophobic polymer gels) are soft materials based on polymeric networks swollen in organic solvents. They are hydrophobic and possess a high content of solvent and low surface adhesion, rendering them interesting in applications such as encapsulants, drug delivery, actuators, slippery surfaces (self-cleaning, anti-waxing, anti-bacterial), or for oil-water separation. To design functional organogels, strategies to control their shape and surface structure are required. Herein, the inherent UV photodegradability of poly(methacrylate) organogels is reported. No additional photosensitizers are required to efficiently degrade organogels (d ≈ 1 mm) on the minute scale. A low UV absorbance and a high swelling ability of the solvent infusing the organogel are found to be beneficial for fast photodegradation, which is expected to be transferrable to other gel photochemistry. Organogel arrays, films, and structured organogel surfaces are prepared, and their extraction ability and slippery properties are examined. Films of inherently photodegradable organogels on copper circuit boards serve as the first ever positive gel photoresist. Spatially photodegraded organogel films protect or reveal copper surfaces against an etchant (FeCl_{3 aq.}).     

Photografting Coating: An Innovative Approach to “Non-Migratory” Active Packaging

The increasing trend of sustainability (single-use packaging), safety (fresh consumption), and convenience (processing and application) in packaging science has created a high demand for packaging materials with advanced functions. Thus, the challenges involved with conventional active packaging, for example, migration, low efficiency, upscaling difficulty, safety, and regulations should be addressed through an industrial scalable method, such as photografting coating. Photografting coating, which involves a strong surface covalent linkage, can be employed for preparing novel “non-migratory” active packaging systems with strong antimicrobial and self-cleaning, antifouling and self-defensive, metal chelating as antioxidant, free-radical scavenging as antioxidant, biocatalytic, and easy printing properties. Herein, profound insights into the technique of photografting coating are provided, with a focus on its application potential in non-migratory active packaging. The scientific explanation for the photografting coating technique and its application feasibility are illustrated to introduce its potential to confer new functions onto packaging materials. Furthermore, the recent progress, application functions, process, and safety challenges, as well as future directions of photografting coating in the preparation of non-migratory active packaging systems are explored in detail.     

Organogels versus Hydrogels: Advantages,Challenges, and Applications

Organogels are an important class of gels, and are comparable to hydrogels owing to their properties as liquid-infused soft materials. Despite the extensive choice of liquid media and compatible networks that can provide a broader range of properties, relatively few studies are reported in this area. This review presents the applicability of organogels concerning their choice of components, unique properties, and applications. Their distinctive features compared to other gels are discussed, including multi-stimuli responses, affinity to a broad range of substances, thermal and environmental stability, electronic and ionic conductivity, and actuation. The active role of solvents is highlighted in the versatility of organogel properties. To differentiate between organogels and other gels, these are classified as gels filled with different organic liquids, including highly polar organic solvents and binary solvent systems. Most promising applications of organogels as sophisticated multifunctional materials are discussed in light of their unique features.     

Self‐Assembling Azaindole Organogel for Organic Light‐Emitting Devices (OLEDs)

This study reports on the use of a self‐assembling organogel, 5‐(4‐nonylphenyl)‐7‐azaindole ( 1 ), as a new emitter in small‐molecule organic light emitting devices (OLEDs). The theoretical calculations along with the photophysical characterization studies suggest the coexistence of the monomer and dimer species at high concentration of compound 1 . The presence of this type of dimer (formed via H‐bonding) is responsible for the increased emission. However, the most notable feature is the 3D network of vastly interconnected fibers formed in the organogel that modifies the photophysical properties. Based on this, several OLED architectures are made in order to understand the mechanism involved in the electroluminescence (EL) behavior of 1 . Although the position of the EL spectra differs from that of the photoluminescence (PL) spectra, the trends observed in the device properties perfectly match with dimer formation. In this framework a better device performance is associated to a higher efficiency of dimer formation, which optimizes in the OLED prepared from the organogel. Therefore, these results show that the rational combination of a moiety showing a strong PL intensity increased upon aggregation with organogel properties is an efficient strategy to create alternative emitters for OLED devices.     

Polymer Microparticles with Controllable Surface Textures Generated through Interfacial Instabilities of Emulsion Droplets

A general and versatile route to prepare hierarchical polymer microparticles via interfacial instabilities of emulsion droplets is demonstrated. Uniform emulsion droplets containing hydrophobic polymers and n‐hexadecanol (HD) are generated through microfluidic devices. When organic solvent diffuses through the aqueous phase and evaporates, shrinking emulsion droplets containing HD and polystyrene (PS) will trigger interfacial instabilities to form microparticles with wrinkled surfaces. Interestingly, surface‐textures of the particles can be accurately tailored from smooth to high textures by varying the HD concentration and/or the rate of solvent evaporation. Moreover, composite particles can be generated by suspending different hydrophobic species to the initial polymer solutions. This versatile approach for preparing particles with highly textured surfaces can be extended to other type of hydrophobic polymers which will find potential applications in the fields of drug delivery, tissue engineering, catalysis, coating, and device fabrication.     

Bioinspired Robust Helical-Groove Spindle-Knot Microfibers for Large-Scale Water Collection

Helical structure is ubiquitous in nature with high-order configuration, specific paths, large superficial areas, providing an approach to bioinspired wettability control. Owing to its special hydrophilic rough surfaces and periodic knot and joint structure, natural spider silk can catch tiny droplets in fog and transport them directionally, sparking scientific interest in bioinspired knotted microfibers to address the risk of water scarcity. To further enhance the water collection ability, a bioinspired helical-groove-modified spindle-knot (HSK) microfiber is continuously fabricated in this work by a simple coating method combined with crack regulation. The formation and morphology can be precisely manipulated by adjusting the drawing velocity and concentration of the coating solution. Compared with smooth spindle-knot microfibers, HSK exhibits greater performances of wetting speed, droplets growth rate, and hanging ability, which can be attributed to the unique helical paths that bring capillary force difference and offer extra three-phase contact line lengths for water collection behavior. The maximum droplet volume is almost 2114 times that of the microfiber knots, which is the highest compared with previous reports. Moreover, HSK microfibers are endowed with repairable wettability, long-term durability, excellent mechanical properties, and flexibility, showing great potential in the realm of applications for large-scale water collection.     

Photoresist deposition without spinning

A technique for resist deposition using a novel fluid ejection method is presented in this paper. An ejector has been developed to deposit photoresist on silicon wafers without spinning. Drop-on-demand coating of the wafer reduces waste and the cost of coating wafers. Shipley 1400-21, 1400-27, 1805, and 1813 resists were used to coat sample 3- and 4-in wafers. Later, these wafers were exposed and developed. The deposited resist film was 3.5 /spl mu/m thick and had a surface roughness of about 0.2 /spl mu/m. The ultimate goal is to deposit resist films with a thickness of the order of 0.5 /spl mu/m and a surface roughness of the order of 30 /spl Aring/, which is currently achieved for 200-mm silicon wafers by using a spinning method. Such goals can be attained by using micromachined multiple ejectors or with better control over the deposition environment. In the micromachined configuration, thousands of ejectors are made into a silicon die, as presented by Percin et al. (2002), and thus allow for a full coating of a wafer in a few seconds. Coating in a clean environment will allow the lithography of circuits for microelectronic applications. Other potential applications for the technology in the semiconductor manufacturing are in deposition of low-k materials, wafer cleaning, manufacturing of organic LEDs and organic FETs, direct lithography, nanolithography, and coating for hard-disk drives.     

Comb Capacitor Structures for On-Chip Physical Uncloneable Function

Planar inter-digitated comb capacitor structures are an excellent tool for on-chip capacitance measurement and evaluation of properties of coating layers with varying composition. These comb structures are easily fabricated in a single step in the last metallization layer of a standard IC process. Capacitive coupling of these structures with a coating layer is modelled based on the electric field distribution to have a detailed understanding of contributing capacitance components. The coating composition is optimized to provide maximum spread in capacitance values of comb capacitor structures. This spread in measured capacitance values can be used to implement a physical uncloneable function (PUF). A PUF is a random function which can be evaluated only with the help of a physical system. We present an on-chip capacitive PUF for chip security and data storage in which the unlock key algorithm is generated from capacitors which are physically linked to the chip in an inseparable way. The strength of this key increases with the spread in capacitance values and measurement accuracy.      

Vapor‐Based Multicomponent Coatings for Antifouling and Biofunctional Synergic Modifications

A general concept is introduced featuring an ideal multifunctional surface that can avoid fouling problems while allowing the installed groups to perform with the high efficacy and accuracy necessary for delivering cascading and spontaneous biological activities. The idea is realized by using a direct synthesis of a multicomponent coating containing the two functionalities of 4‐methyl‐propiolate and 4‐N‐maleimidomethyl that is achieved via chemical vapor deposition copolymerization on various substrates. The novel coating can simultaneously perform specific bio‐orthogonal reactions, including the azide‐alkyne click reaction and a thiol‐maleimide coupling reaction. In the study, azide‐terminated polyethylene glycols are first immobilized on the methyl propiolate groups to impart an antifouling property, while bioactivity is enabled by tethering biotinylated thiols or Cys‐Arg‐Glu‐Asp‐Val (CREDV) peptides on the maleimide groups. The induced antifouling properties and bioactivities are confirmed by quartz crystal microbalance and cell culture studies. Finally, precisely manipulated endothelial cells, namely, human umbilical vein endothelial cells and bovine arterial endothelial cells, are observed on a complex stent substrate and on confined areas of the poly(methyl methacrylate) substrates.     

Novel bi-layer conformal coating for reliability withouthermeticity MEMS encapsulation

A flexible, smooth, and low profile conformal coating was developed to accomplish the encapsulation of a microelectromechanical system (MEMS) device that will be applied to sense the static pressure on aircraft during real flight testing. The encapsulant should be able to protect the MEMS device and the multichip module (MCM) from adverse environmental conditions, i.e., mechanical shock, temperature fluctuation, engine fuel and oil contamination, and moisture/mobile ion permeation. Presently, conventional packaging schemes for electronics cannot satisfy this specific outdoor application, and a new encapsulation combination has been designed in accord with the requirement of reliability without hermeticity (RWOH). A bi-layer structure was selected because of property limitations of a single material. Pliable elastomeric silicones are typically flexible, water repellent, and abrasion resistant. The silicone encapsulant will be first applied to planarize the MEMS surface and function as durable dielectric insulation, stress-relief, and shock/vibration absorbers over a wide humidity/temperature range. To compensate for the deficiency of silicone on engine fuel/oil contamination, Parylene C is to be deposited afterward. This bi-layer coating can achieve excellent bulk properties, such as moisture and mobile ion barrier resistance, chemical compatibility, and electrical insulation characteristics. However, the poor adhesion of Parylene C to silicone greatly restricts its application. To address this problem, silane coupling agents were used as an adhesion promoter. Significant adhesion improvement was achieved by placing an interlayer silane coupling agent to provide interfacial bonding to the silicone elastomeric surface and the Parylene C film. Furthermore, a possible mechanism of adhesion enhancement will also be presented in this study