As one of the most important parts in the surface and interface science, superhydrophobic surfaces play a significant role in both the fundamental research of functional materials and various applications. Therefore, this research field attracts more and more researchers’ attention from all over the world. In the past decades, a large number of biomimetic functional superhydrophobic surfaces have been fabricated inspired from the natural superhydrophobic phenomenon. In this paper, we reviewed the recent advances in the research field of superhydrophobic surfaces, mainly including basic principles, fabrication methods, and applications three aspects. In order to facilitate the comparison, fabrication methods have been divided into three classes at first: coating methods, deposition methods, and the method of direct reproduce (template method). Further, each method is subdivided into several more specific sections such as coatings covering self-assembly coating, grafting coating, electrodeposition, electroless deposition, and so on, according to the theory of the coatings bonding with substrates. For each subsection, the corresponding comments of advantages and partly drawbacks have been summarized. In addition, the peculiar applications of superhydrophobic surfaces, such as waterproof function, antibacterial, antibiofouling, antiscaling, anti-icing, and so on, are also mentioned briefly. Finally, current challenges for this research field are also proposed. The aim of this review is to give a brief and crucial overview of the recent advances in the fabrication of superhydrophobic surfaces.
Three new eudesmanolides, prostrolides A–C (1–3), along with six known compounds were isolated from the herbs of Wedelia prostrata (Asteraceae). The structures were determined by extensive analysis of their spectroscopic data (IR, UV, HRESIMS, 1D and 2D NMR). The isolated compounds were evaluated for their cytotoxic activity on human hepatocellular carcinoma HepG2 cells. All isolates exhibited cytotoxic activities with IC50 values of 4.60 ± 0.17 to 27.23 ± 0.36 µM.
Secondary structure of the glycosylphosphatidylinositol attachment signal (GPI-AS) in GPI-anchored proteins, usually cleaved from the mature protein in eukaryotic cells, was evaluated using circular dichroism (CD). GPI-AS was expressed in Escherichia coli and was purified as a green fluorescent protein (GFP)-fused recombinant protein. The secondary structure was monitored by observing the far-UV CD bands. The α-helix content increased by 3.7% (indicates 13 amino acids) in GFP-fused GPI-AS, indicating that GPI-AS tends to have an α-helical structure. The method we propose in this study can be used to evaluate the secondary structure of the signal regions, which are absent in the mammalian mature proteins.
Crystal growth of Alq3 was achieved in an ionic liquid by vacuum vapor deposition. Alq3 crystals of several tens of microns in size showed beautiful hexagonal morphologies, different from previous reports. The successful crystal growth can be explained by the enhanced migration of Alq3 molecules and moderate supersaturation within the ionic liquid. The Alq3 crystal showed unique optical properties, such as a waveguide and blue-shift of the photoluminescence spectrum.
A novel process was approached to prepare a series of silica–polymer hybrid microspheres prepared from water-in-oil (W/O) suspension containing a suspension of polymer with reactive sites and silica nanoparticles (SiPs) of varying size as aqueous phase. Heating promoted the solidification of the particles. Inorganic microspheres were obtained by simply burning off the organic parts of the hybrid mesoporous microspheres and porosity increases hierarchically from mesoporous to macroporous with the increase of size of SiPs.
A series of 4-hydroxy-1,8-naphthalimides were designed and synthesized for fabrication of amphiphilic dyes and aliphat-π-chromophore-hydroxy (A-π-H) structures. Their aggregation capabilities were examined in water/THF and aggregation-induced formation of micelle structures was confirmed and the structures were characterized. Moreover, the micelles were used as sensors for detection of trace-level water in THF.
We developed a facile and high-recovery system for palladium(II) ion based on complexation between trithiocyanuric acid (TCA) and melamine (Mel) through hydrogen bonding. Recovery of PdII using TCA-Mel complexation system was fast, and the recovery efficiency was greater than 90% within 1 min. The maximum amount of PdII recovered by the TCA-Mel system (1.248 gPd gTCA-Mel−1) was greater than the amount recovered by previously reported materials.
Colloidally stable polystyrene (PS)–polyhedral oligomeric silsesquioxane (POSS) element-block polymer particles were fabricated by heterocoagulation method using negatively charged POSS and positively charged PS seed particles in water. POSS was adsorbed to the PS particle surface via electrostatic interaction and the resulting particles had PS core and POSS shell morphology.
We applied magnesiothermic reduction for porous silica glass, which was prepared from sodium borosilicate glass. The powdered porous silica glass was reduced to silicon and magnesium silicide at temperatures higher than 600 °C. The silicon was isolated by the hydrochloric acid treatment and the subsequent hydrofluoric acid treatment for the reduction products. The SEM observation revealed that the prepared silicon had a porous structure. The pore size distribution measured with a porosimeter was similar to that of the stating porous silica glass in the region less than several tens nanometers.
To understand the requirement of preincubation of betaine-type analogues with enzymes and/or substrates to activate enzyme reactions, we compared α-glucosidase-catalyzed hydrolysis using the analogue 2-(N,N,N-tri-n-butylammonium)acetate and different mixing protocols. We found that enzyme activation is independent of the mixing protocol used and activation initiates immediately following the addition of the analogue to the reaction. Further analysis revealed that facilitation, ascribed to the temporal stabilization of α-glucosidase, is primarily applicable to the active enzyme and not to the denatured protein.
The concise synthesis of a fungal metabolite, (+)-fusarochromanone (FC-101), was achieved via the oxidative sp2 C–H bond olefination of an N-acetylaminochromanone with a chiral functionalized electron-rich alkene, catalyzed by an electron-deficient (η5-cyclopentadienyl)rhodium(III) complex, [CpERhCl2]2, under ambient conditions as the key step. This protocol was applied to various acetanilides and functionalized electron-rich alkenes for the syntheses of fusarochromanone analogs.
A new carboxybetaine-based wedge-shaped bipolar amphiphile is synthesized for self-assembly into an organic nanotube (ONT) at pH 3.0, showing a small inner diameter (<1 nm). The subnanometer nanospace of ONT shows confinement effect, which stabilizes encapsulated small molecules. It shows a better effect than cyclodextrin in the protection of methylene blue from the reduction by glutathione.
We describe the quenching behavior of thermally activated delayed fluorescence (TADF) from 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) by O2 in bis(2-ethylhexyl)sebacate (DOS). Importantly, the high quantum yield of photoluminescence (ϕPL = 0.93) with efficient TADF was dramatically decreased by O2. The quenching rate constants of the S1 and T1 states were estimated to be in the order of 109 and 108 s−1 M−1, respectively. A DOS-plasticized polystyrene film containing 4CzIPN was prepared for optical O2 sensing to determine O2 concentration.
Novel π-extended coumarin-based chromophores were designed with two-photon absorption (TPA) character in the near-IR region. Caged benzoates with a TP-responsive chromophore were synthesized, and their TP-uncaging reactions were conducted under near-IR light. The 6,7-dimethoxy-substituted derivative had a high TPA cross-section of 69 GM at 740 nm. The 7-methoxy-substituted derivative showed a high TPA uncaging efficiency with a TPA efficiency of 3.4 GM at 710 nm.
Nano-SiO2 was functionalized to synthesize a hyperbranched polymer for enhanced oil recovery. The hyperbranched structure, formed by introduction of functionalized Nano-SiO2, endowed the hybrid polymer with excellent shear resistance and viscoelasticity. Based on core flooding experiments, the hybrid polymer could establish good flow resistance and effectively improve oil recovery.
Using magnetic-field-affecting (MFA) water, viscosity of silicate solutions was increased by promotion of microgel formation, which may result in a new route for microgel formation. MFA water made oligomeric silicate species silanol-rich and stabilized the microgels through hydration. Also, the silica gels from silicate solutions prepared using MFA water had small domain size, which seemed to be consistent with the appearance of homogeneous mesopores. These results demonstrate that magnetic treatment of pure water makes MFA water, which affects polymerization and aggregation processes in aqueous silicate solutions.
We have developed a new green method for deposition of silver nanoparticles (Ag NPs) on TiO2. Insoluble solid silver oxalate (Ag2C2O4) is dissolved in an aqueous solution of N,N-dimethyl-1,3-diaminopropane. The alkylamine-activated silver oxalate undergoes TiO2-catalyzed thermal decomposition at low temperatures (<100 °C), leading to high-yield conversion to Ag NPs (>90%). The catalytic activity of the prepared Ag NPs on the TiO2 is evaluated via hydrogenation of 4-nitrophenol.
A GexSi1−x alloy electrode is useful for addressing the shortcomings of a Si negative electrode for lithium-ion batteries. To further improve the electrochemical performance of a GexSi1−x negative electrode, a film-forming additive and the formation of a composite with LaSi2 were applied. A Ge0.1Si0.9 electrode exhibited better cyclability in the additive-containing electrolyte with a discharge capacity of 1240 mA h g−1 at the 400th cycle. In addition, a Ge0.1Si0.9/LaSi2 composite electrode showed better cycle performance than a Ge0.1Si0.9 electrode.
The reaction of 1,3,5-triphenyladamantane-bridged trisbenzimidazolium or trisimidazolium salts bearing long alkyl chains with silver oxide affords trinuclear silver(I) hexacarbene complexes with a three-dimensional organometallic framework in moderate yield, where two tricarbene ligands are linked with three metal centers. The complex self-assembles into hollow spherical aggregates in a polar organic solution.
The Maillard reaction is one of the dominant processes forming humic substances in natural waters affecting environmental pollution. In this study, we succeeded in quantitatively following decreases of starting materials (glycine and ribose) of the Maillard reaction by in situ infrared (IR) transmission spectroscopic observations with an original heatable liquid cell. The obtained kinetic parameters extrapolated to a typical Earth’s surface aquatic environments (15 °C) indicate the half-life of around 2 years for the decrease of these components as the first step for the formation of humic substances.
We report a method to establish experimental conditions for surface-enhanced Raman scattering (SERS) spectroscopy in order to avoid thermal damage on heat-sensitive materials by monitoring thermal desorption of thiolate molecules from a metal surface. Thiolate molecules adsorbed on gold desorb at 60–100 °C, which corresponds to the denaturation or degradation temperature of heat-sensitive materials (e.g. DNA, proteins, polymers, and lipid membranes). By observing the change in Raman signal from the thiolates on SERS substrate, it is possible to estimate the maximum power of excitation laser required for the samples to reach their critical temperatures for thermal degradation.
The title reaction of silylethynyl 2,6-(tBu)2phenyl ethers took place in the presence of a palladium catalyst and pivalic acid to give 2-silylmethylenechromanes. The initial products were converted by treatment with acetic acid to thermodynamically stable 4H-chromenes, which were further reacted with activated aldehyde and ketone.
We report an Fe/Cu/N-doped carbon electrocatalyst for the oxygen reduction reaction to water. Pyrolysis of metal precursors supported on oxidized carbon black provides the electrocatalyst with high catalytic activity and selectivity. Detailed physical–chemical studies have revealed that the copresence of iron and copper catalytic sites in carbon in a 1:1 mole ratio, which is the same as that of an enzyme of cytochrome c oxidase, might be the key to synthesize highly active and selective electrocatalysts.
Herein, we report the straightforward synthesis of unsheathed insulated molecular wires through Yamamoto reductive polycondensation. Despite the step-growth mechanism, block copolymers could be obtained because of the difference in the reactivities of the sheathed and unsheathed monomers. We expect that such a unique structure could find use as a charge-transporting wire in molecular electronics.