Inorganic-Organic Silica/PDMS Nanocomposite Antiadhesive Coating with Ultrahigh Hardness and Thermal Stability.

Antiadhesive surfaces have been gaining continuous attention, because of the scientific and industrial significance. Slippery surfaces and antismudge coatings with antiadhesive behavior have been readily designed and prepared. However, improving robustness of the surfaces, especially the simultaneous demonstration of features of high hardness, excellent adhesion to different substrates, and high thermal stability, is constantly challenging. Herein, we present a silica/polydimethylsiloxane (PDMS) nanocomposite coating (SPNC), wherein silica acts as a consecutive phase and nanophased PDMS is covalently embedded. The nanoconfined PDMS phase exhibits enhanced thermal stability and endows SPNC with slippery behavior; meanwhile, enrichment of PDMS on the surface renders a gradient composition of the coating. Accordingly, the inorganic-organic SPNC simultaneously displays a high nanoindentation hardness of 3.07 GPa and a pencil hardness over 9H, outstanding thermal stability of the slippery performance up to 400 °C, and excellent adhesion strength to different substrates. Additionally, SPNC exhibits high optical transparency, flexibility, resistance to bacterial clone, and chemical corrosion. With the scalable fabrication process, it can be envisioned that the antiadhesive coating with unprecedented comprehensive merits in this work has significant potentials for large-area applications, especially under severe service environments.

In Situ Combustion Synthesis of Gr/h-BN Composites and Its Passive Heat Dissipation Application.

To enhance the infrared radiation efficiency and the heat transfer performance simultaneously, graphene (Gr) was synthesized in situ on hexagonal boron nitride (h-BN) to prepare Gr/h-BN composites by a scalable combustion synthesis in CO2 atmosphere using Mg as sacrificial solder. The synthesized Gr/h-BN composites were added in polydimethylsiloxane polymer to prepare composite coatings, which show an infrared emissivity greater than 0.95 and a through-plane thermal conductivity up to 2.584 W·m-1·K-1. When functioning on an Al heatsink, such a composite coating can reduce the temperature by as much as 21.7 °C. Meanwhile, the composite coating exhibits superior adhesion on the Al substrate. Therefore, Gr/h-BN composite coatings with noteworthy infrared radiation and thermal conductivity are expected to be a promising candidate for heat dissipation applications.

Strong Hydration Ability of Silk Fibroin Suppresses Formation and Recrystallization of Ice Crystals During Cryopreservation.

The cryopreservation (CP) of cell/tissue is indispensable in medical science. However, the formation of ice during cooling and ice recrystallization/growth in time of thawing present significant risk of cell/tissue damage upon analysis of CP process. Herein, the natural and biocompatible silk fibroin (SF) with regular hydrophobic and hydrophilic domains, were first employed as a cryoprotectant (CPA), to the CP of human bone-derived mesenchymal stem cells (hBMSCs), which has been routinely cyropreserved for cell-based therapies. Addtion of SF can regulate the formation of ice crystals during cooling process because of its strong hydration ability in the comparation to the cryopreservation medium (CM) without SF. Moreover, the devitrification-induced recrystallization/growth of ice during the thawing process is suppressed. Most importantly, the addition of 10 mg mL-1 SF can achieve 81.28% cell viability of cryopreserved hBMSCs as similar as those with the addition of 180 mg mL-1 Ficoll 70 (commercial CPA), and the functions of the cryopreserved hBMSCs are maintained as good as that of the fresh ones. This work is not only significant for meeting the ever-increasing demand of cell therapy, but also trailblazing for designing materials in controlling ice formation and growth during the CP of other cells and tissues.

Bioinspired in situ repeatable self-recovery of superhydrophobicity by self-reconstructing the hierarchical surface structure.

Inspired by the biological self-recovery mechanism of superhydrophobicity, a new class of waxgel material with sustainable hierarchical surface micro-structures has been reported. After being damaged or removed, the waxgel material can self-reconstruct its surface layer both chemically and structurally, as well as successfully recovers its superhydrophobicity. In addition, it shows non-fluorinated composition, durability to severe mechanical challenges, and self-recoverable surface structures without external input of any kind such as; heat, UV, plasma etc., which distinguishes waxgel from any previous self-healing superhydrophobic systems. This strategy will open a new path for improving the long-term functionality of different interfacial materials.

Solar anti-icing surface with enhanced condensate self-removing at extreme environmental conditions.

The inhibition of condensation freezing under extreme conditions (i.e., ultra-low temperature and high humidity) remains a daunting challenge in the field of anti-icing. As water vapor easily condensates or desublimates and melted water refreezes instantly, these cause significant performance decrease of most anti-icing surfaces at such extreme conditions. Herein, inspired by wheat leaves, an effective condensate self-removing solar anti-icing/frosting surface (CR-SAS) is fabricated using ultrafast pulsed laser deposition technology, which exhibits synergistic effects of enhanced condensate self-removal and efficient solar anti-icing. The superblack CR-SAS displays superior anti-reflection and photothermal conversion performance, benefiting from the light trapping effect in the micro/nano hierarchical structures and the thermoplasmonic effect of the iron oxide nanoparticles. Meanwhile, the CR-SAS displays superhydrophobicity to condensed water, which can be instantly shed off from the surface before freezing through self-propelled droplet jumping, thus leading to a continuously refreshed dry area available for sunlight absorption and photothermal conversion. Under one-sun illumination, the CR-SAS can be maintained ice free even under an ambient environment of -50 °C ultra-low temperature and extremely high humidity (ice supersaturation degree of ∼260). The excellent environmental versatility, mechanical durability, and material adaptability make CR-SAS a promising anti-icing candidate for broad practical applications even in harsh environments.

Adductor canal block combined with local infiltration analgesia versus isolated adductor canal block in reducing pain and opioid consumption after total knee arthroplasty: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the efficacy and safety of the addition of local infiltration analgesia (LIA) to adductor canal block (ACB) for pain control after primary total knee arthroplasty (TKA). METHODS: Two reviewers independently searched for potentially relevant published studies using electronic databases, including PubMed® (1966 to June 2019), Embase® (1974 to June 2019) and Web of Science (1990 to June 2019). The results were pooled using the random-effects model to produce standard mean differences for continuous outcome data and odds ratio for categorical outcome data. RESULTS: A total of three randomized controlled trials (RCTs) and three non-RCTs were included for data extraction and meta-analysis. There were significant differences between the two groups regarding the postoperative pain score on postoperative day (POD) 0 and POD 1. The cumulative opioid consumption in the ACB plus LIA groups was significantly lower than that in the ACB groups on POD 0 and POD 1. No significant differences were found in terms of postoperative range of motion or length of hospitalization. CONCLUSION: ACB plus LIA significantly reduced the postoperative pain score on POD 0 and POD 1 compared with isolated ACB. In addition, ACB plus LIA was associated with a significant reduction in opioid consumption during the early postoperative period.

Size-Dependent Interfacial Assembly of Graphene Oxide at Water-Oil Interfaces.

The interfacial assembly of graphene oxide (GO) at the water/oil interface was investigated using pendant drop tensiometry as a function of the pH, GO size and concentration, and molecular weight of the polymer ligands. It was found that the smaller the lateral dimension of the GO sheets, the more rapidly the interfacial tension decreased, and the lower was the interfacial tension between the oil and water. The differences in the rates at which the interfacial tension decreased are related to the diffusion of the GO to the interface, the presentation of the GO at the interface, the degree of functionalization relative to the surface area, and the in-plane motion of the GO to accommodate the arrival of more GO at the interface to effectively cover the interface. The solidlike film formed at the interface had a modulus that increased with decreasing lateral GO dimensions.

Rationally designed surface microstructural features for enhanced droplet jumping and anti-frosting performance.

The accretion of frost on heat exchanging surfaces through the freezing of condensed water in cold and humid environments significantly reduces the operating efficiency of air-source heat pumps, refrigerators and other cryogenic equipment. The construction of hierarchical micro-nanostructured SHSs, with the ability to timely remove condensed water before freezing via self-propelled droplet jumping, serves as a promising anti-frosting strategy. However, the actual relationship between microstructural features and water removal capability through droplet jumping is still not clear, hindering the further optimization of anti-frosting SHSs. Herein, a series of aluminum SHSs with different micro-cone arrays is designed and fabricated via ultrafast laser processing and chemical etching. The effect of microstructural features on water removal capability is elucidated by statistically analyzing the condensation process. As compared to nanostructured SHSs with the micro-cone size ranging from 10 to 40 µm, the water removal through droplet jumping is remarkably enhanced from 3.42 g m-2 to as much as 13.91 g m-2 over 10 minutes of condensation experiments due to the effective transition of condensed microdroplets from the initial high-adhesion partial wetting (PW) state to low-adhesion Cassie state, leading to significantly reduced water accumulation and improved anti-frosting performance. However, a further increase in the micro-cone size decreased the water removal amount due to greater droplet adhesion to the surface, which results in higher chances for immobile coalescence and the formation of large droplets. Herein, by rationally tuning the size scale of the structured micro-cones, the optimal SHSs display the least water accumulation and render excellent frosting delay of over 90 minutes under simulated harsh operating conditions.

Competing Effects between Condensation and Self-Removal of Water Droplets Determine Antifrosting Performance of Superhydrophobic Surfaces.

Preventing condensation frosting is crucial for air conditioning units, refrigeration systems, and other cryogenic equipment. Coalescence-induced self-propelled jumping of condensed microdroplets on superhydrophobic surfaces serves as a favorable strategy against condensation frosting. In previous reports, efforts were dedicated to enhance the efficiency of self-propelled jumping by constructing appropriate surface structures on superhydrophobic surfaces. However, the incorporation of surface structures results in larger area available for condensation to occur, leading to an increase in total amount of condensed water on the surface and partially counteracts the effect of promoted jumping on removing condensed water from the surface. In this paper, we focus on the competing effects between condensing and self-propelled jumping on promoting and preventing water accumulation, respectively. A series of micro- and nanostructured superhydrophobic surfaces are designed and prepared. The condensation process and self-propelled jumping behavior of microdroplets on the surfaces are investigated. Thousands of jumping events are statistically analyzed to acquire a comprehensive understanding of antifrosting potential of superhydrophobic surfaces with self-propelled jumping of condensed microdroplets. Further frosting experiments shows that the surface with the lowest amount of accumulated water exhibits the best antifrosting performance, which validates our design strategy. This work offers new insights into the rational design and fabrication of antifrosting materials.

Interfacial Materials for Anti-Icing: Beyond Superhydrophobic Surfaces.

The design and fabrication of interfacial materials for anti-icing is of great importance, since undesired ice accumulation leads to serious economic, energy, and safety issues. Substantial progress on interfacial materials for the passive removal of ice has been achieved in the past three years. The present focus review critically summarizes and analyzes recent breakthroughs in interfacial materials for anti-icing. In particular, we focus on the effect of surface textures on the timely removal of water droplets, the microscopic mechanism of ice formation, and the effect of an interfacial layer's properties on easy shedding of formed ice with a view towards designing high-performance and durable interfacial materials for anti-icing beyond superhydrophobic materials.

Antiadhesion Organogel Materials: From Liquid to Solid.

Various organogel materials with either a liquid or solid surface layer have recently been designed and prepared. These surface materials can substantially reduce the adhesion of foreign deposits such as water, blood, paint, ice, and so on; therefore, they exhibit great potential for the easy removal of foreign deposits. Here, a brief discussion about the mechanism of organogel materials in reducing adhesion is given; then, examples of liquid organogels for fighting against varieties of complex fluidic deposits are presented, and efforts in preventing the depletion of liquid are discussed. Finally, applications of antiadhesion organogels with multifunctionality, and the strategy of replacing liquids with solids are presented.

Bioinspired Solid Organogel Materials with a Regenerable Sacrificial Alkane Surface Layer.

In nature, lifetime-long functionalities of land plant leaves rely on the regenerability as well as the solid feature of the epicuticular wax layer. Inspired by the regenerable solid epicuticular wax on land plant leaf surfaces, herein a type of solid organogel material with regenerable sacrificial alkane surface layer is reported. This type of surface material is demonstrated to be of great practical importance for tackling solid deposition, such as anti-icing, antigraffiti, and antifouling, since the deposited foreign materials can be easily removed together with the alkane surface layer. Significantly, the solid alkane layer does not contaminate nearby surfaces due to its solid nature in both working and stand-by conditions, which is completely different to liquid-infused materials.

Anti-ice coating inspired by ice skating.

Accumulation of ice to surfaces brings dangerous and costly problems to our daily life. In this paper, an anti-ice coating inspired by ice skating is reported. Hyaluronic acid is used in the anti-ice coating to form aqueous lubricating layer benefitting from its high water absorbing property. Dopamine, the main component of the mussel adhesive protein, is introduced to anchor the hyaluronic acid to the solid surfaces to render the coating applicable to all types of solid surfaces. At the same time it serves as the crosslinking agent for hyaluronic acid, thus the thickness of the water collecting film could be easily varied. Ice adhesion strength on surfaces coated with such kind of coating could be more than one order of magnitude lower than that of uncoated ones. The results indicate that this anti-ice coating with the aqueous lubricating layer has great potential for fighting against icing problems.

Bio-inspired strategies for anti-icing.

Undesired ice accumulation leads to severe economic issues and, in some cases, loss of lives. Although research on anti-icing has been carried out for decades, environmentally harmless, economical, and efficient strategies for anti-icing remain to be developed. Recent researches have provided new insights into the icing phenomenon and shed light on some promising bio-inspired anti-icing strategies. The present review critically categorizes and discusses recent developments. Effectively trapping air in surface textures of superhydrophobic surfaces weakens the interaction of the surfaces with liquid water, which enables timely removal of impacting and condensed water droplets before freezing occurs. When ice already forms, ice adhesion can be significantly reduced if liquid is trapped in surface textures as a lubricating layer. As such, ice could be shed off by an action of wind or its gravity. In addition, bio-inspired anti-icing strategies via trapping or introducing other media, such as phase change materials and antifreeze proteins, are discussed.