Excellent Waterproof Properties Research Articles

(Invited) soft, Wireless Pressure-Sensor-Integrated Smart Bandage for the Management of Wound Healing

Soft, flexible electronics are promising for many applications including health monitoring, soft robotics, and other intelligent systems. In this talk, I will discuss our recent efforts in developing flexible electronic devices with previously inaccessible capabilities. I will start with our work on soft, wireless pressure-sensor-integrated smart bandage for the management of diabetic foot ulcers. Diabetic foot ulcers (DFUs) have affected millions of people in the U.S. and posed heavy burdens to patients and the healthcare system due to their being slow to heal, high recurrence rate, and potential risk of amputation and even premature death. A mainstay of DFU therapy is mechanical offloading to mitigate pressure at the ulcer, which, however, is usually not effective due to patients’ diminished sensation capabilities on the foot and low adherence to offloading recommendations. I will present our recent effort in developing a soft, flexible, wireless pressure-sensor-integrated smart bandage system for continuously monitoring the pressure on the foot and alerting the users to offload under exceeded pressure. The pressure sensor exhibits high linearity, negligible hysteresis, fast response time, and excellent water-proof properties relevant for this application. Wireless data transmission onto a smartphone via Bluetooth enables the display and interpretation of the measured pressure with the option of a preset pressure threshold, when exceeded, an alert will be generated for immediate notifications. Trials on healthy subjects demonstrate reliable monitoring performance and effectiveness in aiding offloading. The developed smart bandage system represents a significant advance in the prevention and management of DFUs and other pressure injuries as well as compression therapy corrections.

Mussel-inspired waterproof and self-healing polyurethane with enhanced mechanical properties

• The mussel-inspired polyurethane with self-healing and waterproof properties were successfully synthesized. • The self-healable polyurethane exhibits rapid room-temperature self-healing ability. • The self-healable polyurethane possesses excellent waterproof property. • The self-healable polyurethane shows remarkable deformation recovery properties, tear-resistance, and toughness. Polyurethane-based devices always suffer from complex environment during their service life. Therefore, excellent and well-balanced properties like self-healing, waterproof, and mechanical properties are necessary. Nevertheless, it is challenging and usually contradictory to achieve them simultaneously. In this work, a series of novel mussel-inspired graphene oxide/polyurethane composites were designed and successfully synthesized. The composites show high stress ( η 1 ) and strain ( η 2 ) self-healing efficiency of 87% and 91% respectively, while their tensile strength is increased by 84% with a high strain of 2190% at the same time. Especially, the self-healing properties were hardly affected after the soaking experiment, determining the outstanding waterproof behavior. Additionally, the composites also possess preferable tear-resistance and toughness. Even cut with a 2 mm width notch, they could still bear the high strain of 1152%. More importantly, the composites also show remarkable deformation recovery properties under both cyclic tensile and compressive loads. It is expected that this polyurethane may be potentially applied in solid propellants, protective coating, electronic skin, soft sensors, and other devices.

Bioinspired Oil-Infused Slippery Surfaces with Water and Ion Barrier Properties.

Encapsulation materials play an important role in many applications including wearable electronics, medical devices, underwater robotics, marine skin tagging system, food packaging, and energy conversation and storage devices. To date, all the encapsulation materials, including polymer layers and inorganic materials, are solid materials. These solid materials suffer from limited barrier lifetimes due to pinholes, cracks, and nanopores or from complicated fabrication processes and limited stretchability for interfacing with complex 3D surfaces. This paper reports a solution to this material challenge by demonstrating bioinspired oil-infused slippery surfaces with excellent waterproof property for the first time. A water vapor transmission test shows that locking a thin layer of oil on the silicone elastomer improves the water vapor barrier performance by three orders of magnitude. Accelerated lifetime tests suggest robust water barrier characteristics that approach 226 days at 37 °C even under severe mechanical damage. A combination of temperature- and thickness-dependent experimental measurements and reaction-diffusion modeling reveals the key waterproof property. In addition to serving as a barrier to water, the oil-infused surface demonstrates an attractive ion barrier property. All these exceptional properties suggest the potential applications of slippery surfaces as encapsulation materials for medical devices, underwater electronics, and many others.

Preparation of Superhydrophobic Fabric Based on the SiO2@PDFMA Nanocomposites by an Emulsion Graft Polymerization and a Hot‐Pressing Process

AbstractWe report a facile method to fabricate superhydrophobic fabric based on the silica@poly (dodecafluoroheptyl methacrylate) (SiO2@PDFMA) nanocomposites by emulsion graft polymerization and hot‐pressing process. The coated fabric without using resin adhesive demonstrated robust abrasion resistance, UV resistance, efficiently repel various liquids, excellent waterproof property, and good self‐cleaning performance. Intriguingly, the superhydrophobic coating has a little adverse effect on the important textile physical properties, such as the fabric color, air permeability, and color fastness. The robust superhydrophobicity was considered to be related to the following reasons. First, the Nano‐SiO2 and fibers provide micro‐nanoscale roughness, and PDFMA has excellent chemical/ultraviolet resistance and low surface energy. Their combination endows the fabric superhydrophobicity. Moreover, by the mean of hot‐pressing (at 120 °C under 0.2 MPa), the SiO2@PDFMA nanocomposites were firmly riveted to fibers. These results demonstrate a process particularly suitable for fabrics, and the coatings are expected to be practically applied in the textile industry.

Fabrication of Waterproof Artificial Compound Eyes with Variable Field of View Based on the Bioinspiration from Natural Hierarchical Micro\u2013Nanostructures

HighlightsBioinspired by natural superhydrophobic surface with hierarchical micro–nanostructures, waterproof artificial compound eyes with variable field of view (FOV) were fabricated by a simple and effective manufacturing method.The fabricated artificial compound eyes exhibited excellent waterproof property, tunability of the FOV and optical performance.

Stretchable conductive nonwoven fabrics with self-cleaning capability for tunable wearable strain sensor

With the fast growth of wearable intelligent devices, tunable strain sensors with broad strain sensing range and high sensitivity are in urgent demand. Furthermore, the merits of excellent waterproof property, self-cleaning, and anti-corrosion are also imperative for the practical applications of them. Herein, a tunable wearable micro-cracked non-woven fabrics (NWF) strain sensor with broad strain sensing range and high sensitivity was successfully developed based on the electrically conductive cellulose nanocrystal (CNC)/graphene (G) coating with controllable micro-crack density, which was achieved through changing the G loading of the coating layer, and its superhydrophobicity was achieved by simply dip-coating in the hydrophobic fumed silica (Hf-SiO2)/ethanol dispersion. As a result, a broad working range of 98% and GF value up to 2.36 × 104 are simultaneously achieved for the prepared strain sensor (G content is 25 wt%). In addition, it possesses an ultralow detection limit as low as 0.1%, short response time (33 ms) and good sensing stability over 1000 cycles. What's more, the NWF strain sensor presents excellent waterproofness (WCA = 154°), anti-corrosion ability, outstanding self-cleaning and stability. Due to the excellent response performances, the NWF strain sensor can successfully monitor various human activities from subtle deformations (e.g. speech recognition, pulse waves) to vigorous body movements (e.g. finger, elbow joint and wrist movement). Specially, owing to its excellent superhydrophobic characteristic, the strain sensor also exhibits superior self-cleaning capability and good applicability in a humid or underwater harsh outdoor environment.

Mechanically Durable, Highly Conductive, and Anticorrosive Composite Fabrics with Excellent Self-Cleaning Performance for High-Efficiency Electromagnetic Interference Shielding.

Metal-based materials have been widely used for the electromagnetic interference (EMI) shielding due to their excellent intrinsic conductivity. However, their high density, poor corrosion resistance, and poor flexibility limit their further application in aerospace and flexible electronics. Here, we reported a facile means to prepare lightweight, mechanically durable, superhydrophobic and conductive polymer fabric composites (CPFCs) with excellent electromagnetic shielding performance. The CPFC could be fabricated by three steps: (1) the polypropylene (PP) fabric was coated by a polydopamine (PDA) layer; (2) PP/PDA adsorbed the Ag precursor that was then chemically reduced to Ag nanoparticles (AgNPs); (3) PP/PDA/AgNPs fabricswere modified by one layer of polydimethylsiloxane (PDMS). The contact angle (CA) of the CPFCs could reach ∼152.3° while the sliding angle (SA) was as low as ∼1.5°, endowing the materials with excellent self-cleaning performance. Thanks to the extremely high conductivity of 81.2 S/cm and the unique porous structure of the fabric, the CPFC possessed outstanding EMI shielding performance with the maximum shielding effectiveness (SE) of 71.2 dB and the specific shielding effectiveness (SSE) of 270.7 dB cm3 g-1 in the X band. The interfacial adhesion is remarkably improved owing to the PDMS layer, and the superhydrophobicity, conductivity and EMI SE of CPFCs are almost maintained after cyclic abrasion and winding test. Also, the CPFCs can be used in a harsh environment, due to their excellent water proof property.

Antimicrobial cotton textiles with robust superhydrophobicity via plasma for oily water separation

During these decades, functional materials are facing the severe challenge of their weak surface structure. To solve this problem, plasma technology and spraying technology were utilized to improve the bonding effect between cotton substrates and coating structures. Herein, silica/silver nanoparticles (SiO2/Ag NPs) were prepared and introduced to the nano-/micro- structures on sample surface by spraying technology in the existence of polyurethane adhesive. Then the circles of spraying procedure containing adhesive and SiO2/Ag NPs had been discussed. After further fluorination, the samples still displayed an excellent waterproof property even after abrasion test with sand paper and various washing test by its solvent–acetone or harsh liquids with strong acidity/alkalinity, indicating their robust surfaces structures. More importantly, this product displayed the outstanding performance no matter in laboratory oil/water filtration or the extensive oil leakage and spill. At last, our modification also endowed the cotton sample with great antimicrobial property.

The Research of Waterproof Used on Mudstone

The paper launched a study of waterproof material for mudstone in gas drilling. The adhesion with rock surfaces and water resistance of four synthetic waterproof materials were experimentally evaluated. The results showed that the four synthetic waterproof materials had a good adhesion to the surface of the rock, which could meet operational requirements in the vertical plane. The synthetic waterproof materials had excellent waterproof property, and could withstand immersion in water of more than 72h.

Preparation of PVDF Nanofibrous Membrane and its Waterproof and Breathable Property

PVDF nanofibrous membranes were successfully prepared by electrospinning in this paper, and the component solvent of DMF/acetone was used. The concentration of PVDF and the volume ratio of component solvents of DMF/acetone were the most important variables to affect the morphology, diameter and uniformity of the nanofibers. The concentration of spinning fluid changed from 10 wt% to18 wt% and the volume ratio of DMF/acetone ranged from 2/8 to 8/2. The results of the study showed that the better nanofibrous membrane was prepared when the concentration of PVDF was 12 wt% and the ratio of component solvent DMF/acetone was 6/4. At this moment, the morphology and contact angle of PVDF membrane were better in comparison with other groups. The contact angle, waterproof properties, air permeability were measured, which indicated that the PVDF nanofibrous membrane showed a good air permeability and had an excellent waterproof properties at the same time. In the meantime, by changing the thickness of membrane, we could analyze the relationship between the thickness of the membrane and its breathability and waterproofness.

Fluorinated siloxane-containing waterborne polyurethaneureas with excellent hemocompatibility, waterproof and mechanical properties

Two series of polyurethaneurea (PUU) aqueous dispersions consisting of fluorinated siloxane segments were prepared from a high-molecular-weight ( M n = 8361) α,ω-dihydroxypoly[(3,3,3-trifluoropropyl)methylsiloxane] (PTFPMS), dimethylolpropionic acid, isophorone diisocyanate and ethylenediamine, with poly (tetramethylene oxide) and polycarbonate polyols as soft segments, respectively. These anionic aqueous dispersions were stable at the ambient temperature for more than 6 months, with particle sizes ranging from 45 to 98 nm. Both series of PUU films showed the excellent waterproof properties, i.e. the decrease in water absorption and surface energy upon the incorporation of PTFPMS segments. The phase mixing increased in the fluorinated siloxane-containing polyether-based PUUs and the phase separation increased first then decreased in the fluorinated siloxane-containing polycarbonate-based PUUs, with increasing PTFPMS content. All the PTFPMS-modified PUU films showed excellent mechanical properties. The polycarbonate-based PUU film consisting of 5 wt.% PTFPMS had a tensile strength of 60.7 MPa and a breaking elongation of 632%, owing to the increase in the ordered hydrogen bonding degree and the microphase-separation degree between the hard and soft segments in the system. In vitro hemolysis and dynamic clotting time measurements indicated that the thromboresistance was enhanced markedly with increasing PTFPMS content for both series of PUUs, which could be ascribed to the synergistic effect between the carboxylate groups and the PTFPMS segments migrating onto the surfaces of the films.

Preparation of waterborne polyurethanes using an amphiphilic diol for breathable waterproof textile coatings

The application of polyurethanes (PUs) on breathable waterproof fabric coatings requires a balance of water vapor permeability (WVP) and water resistance which can be achieved by tailoring hydrophilic and hydrophobic segments. PU prepolymers were prepared from isophorone diisocyanate, dimethylol butanoic acid, and a mixture of various ratios of amphiphilic PPG2050 (copolymer of ethylene oxide and propylene oxide with –OH end groups) and hydrophobic poly(tetramethylene ether glycol) (PTMEG). After neutralization with triethylamine, the prepolymers were chain-extended with ethylene diamine/1,4-butanediol (1:1 by molar). The WVP values of the fabric coatings prepared using various waterborne PUs were very similar (910–990 g/m 2 × 24 h). When waterborne PUs prepared using a mixture of PPG2050 and PTMEG were employed for the textile coatings, the resulting PU-coated textiles exhibited excellent waterproof properties (>10,000 mm H 2O). The textile coatings prepared from PPG2050/PTMEG-based waterborne PUs were significantly more waterproof than those prepared from poly(ethylene glycol) (PEG)/poly(propylene glycol) (PPG)/PTMEG-based waterborne PU. This is probably due to a more even distribution of hydrophobic segments in the PUs, even though the WVP values of the PEG/PPG/PTMEG-based PU coatings were considerably smaller than those of the PPG2050/PTMEG-based PU coatings.

Manufacture of composite board using wood prunings and waste porcelain stone

The objective of this study was to develop a method for the effective use of both pruned wood and porcelain stone scrap. Thus, we manufactured a wood-porcelain stone composite board, which has excellent waterproof property and incombustibility properties. In addition, we examined the conditions needed to manufacture the wood-porcelain stone composite board as a construction material and evaluated the physical and mechanical properties of this board based on the Japanese Industrial Standard. The main results obtained were as follows: the wood-porcelain stone composite board made from pruned wood and porcelain stone scrap had excellent thickness swelling performance and the board had incombustibility properties that were better than commercial oriented strand board. In both single-layer and three-layer composite boards with weight ratios of porcelain stone particles of 40%, the internal bond strength exceeded the standard value of type 18 particleboard of JIS A 5908. However, the bending properties of the composite board were inferior to the type 18 particleboard standard. Therefore, it will be necessary to improve the bending properties of the board by changing the particle sizes of both the porcelain stone scrap and the pruned wood component.