Showing papers in "Langmuir in 2018"
TL;DR: Light is shed on the hypothesis that bulk nanobubbles do exist, they are filled with gas, and they survive for long periods of time, challenging present theories.
Abstract: Bulk nanobubbles are a novel type of nanoscale bubble system. Because of their extraordinary behavior, however, their existence is not widely accepted. In this paper, we shed light on the hypothesis that bulk nanobubbles do exist, they are filled with gas, and they survive for long periods of time, challenging present theories. An acoustic cavitation technique has been used to produce bulk nanobubbles in pure water in relatively large numbers approaching 109 bubble·mL–1 with a typical diameter of 100–120 nm. We provide multiple evidence that the nanoentities observed in suspension are nanobubbles given that they disappear after freezing and thawing of the suspensions, their nucleation rate depends strongly on the amount of air dissolved in water, and they gradually disappear over time. The bulk nanobubble suspensions were stable over periods of many months during which time the mean diameter remained unchanged, suggesting the absence of significant bubble coalescence, bubble breakage, or Ostwald ripening ...
198 citations
TL;DR: Results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that differentThiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.
Abstract: Eutectic gallium-indium alloy (EGaIn, a room-temperature liquid metal) nanoparticles are of interest for their unique potential uses in self-healing and flexible electronic devices. One reason for their interest is due to a passivating oxide skin that develops spontaneously on exposure to ambient atmosphere which resists deformation and rupture of the resultant liquid particles. It is then of interest to develop methods for control of this oxide growth process. It is hypothesized here that functionalization of EGaIn nanoparticles with thiolated molecules could moderate oxide growth based on insights from the Cabrera-Mott oxidation model. To test this, the oxidation dynamics of several thiolated nanoparticle systems were tracked over time with X-ray photoelectron spectroscopy. These results demonstrate the ability to suppress gallium oxide growth by up to 30%. The oxide progressively matures over a 28 day period, terminating in different final thicknesses as a function of thiol selection. These results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that different thiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.
141 citations
TL;DR: High-contrast wetting patterns collected the highest amount of fog and enhanced the fog-collection efficiency by nearly 60% compared to pristine Pyrex glass, showing that the superior fog- collection efficiency of surface patterns with extreme wetting contrast is due to the combination of water attraction and water repellency.
Abstract: The exciting functionalities of natural superhydrophilic and superhydrophobic surfaces served as inspiration for a variety of biomimetic designs. In particular, the combination of both extreme wetting states to micropatterns opens up interesting applications, as the example of the fog-collecting Namib Desert beetle shows. In this paper, the beetle’s elytra were mimicked by a novel three-step fabrication method to increase the fog-collection efficiency of glasses. In the first step, a double-hierarchical surface structure was generated on Pyrex wafers using femtosecond laser structuring, which amplified the intrinsic wetting property of the surface and made it superhydrophilic (water contact angle 150°). In the last step, the Teflon-like coating was selectively removed by fs-laser ablation to uncover superhydrophilic spots below the supe...
128 citations
TL;DR: This study synthesized colloidal bioinks composed of disk-shaped two-dimensional nanosilicates (Laponite) and poly(ethylene glycol) (PEG) and increases viscosity, storage modulus, and network stability, introducing a new class of PEG-Laponites colloidal inks for bioprinting and cell delivery.
Abstract: Nanoengineered hydrogels offer the potential to design shear-thinning bioinks for three-dimensional (3D) bioprinting. Here, we have synthesized colloidal bioinks composed of disk-shaped two-dimensional (2D) nanosilicates (Laponite) and poly(ethylene glycol) (PEG). The addition of Laponite reinforces the PEG network and increases viscosity, storage modulus, and network stability. PEG-Laponite hydrogels display shear-thinning and self-recovery characteristics due to rapid internal phase rearrangement. As a result, a range of complex patterns can be printed using PEG-Laponite bioinks. The 3D bioprinted structure has similar mechanical properties compared to the as-casted structure. In addition, encapsulated cells within the PEG-Laponite bioink show high viability after bioprinting. Overall, this study introduces a new class of PEG-Laponite colloidal inks for bioprinting and cell delivery.
127 citations
TL;DR: Nanostructured copper sulfide synthesized with the assistance of surfactant with nanoscale particle size and high Brunauer-Emmett-Teller surface area was for the first time applied for the capture of elemental mercury (Hg0) from coal combustion flue gas and appears to be a highly promising alternative to traditional sorbents for Hg0 capture.
Abstract: Nanostructured copper sulfide synthesized with the assistance of surfactant with nanoscale particle size and high Brunauer–Emmett–Teller surface area was for the first time applied for the capture of elemental mercury (Hg0) from coal combustion flue gas The optimal operation temperature of nano-CuS for Hg0 adsorption is 75 °C, which indicates that injection of the sorbent between the wet flue gas desulfurization and the wet electrostatic precipitator systems is feasible This assures that the sorbent is free of the adverse influence of nitrogen oxides Oxygen (O2) and sulfur dioxide exerted a slight influence on Hg0 adsorption over the nano-CuS Water vapor was shown to moderately suppress Hg0 capture efficiency via competitive adsorption The simulated adsorption capacities of nano-CuS for Hg0 under pure nitrogen (N2), N2 + 4% O2, and simulated flue gas reached 12240, 11206, and 8943 mgHg0/g nano-CuS, respectively Compared to those of traditional commercial activated carbons and metal sulfides, the
122 citations
TL;DR: This article critically categorizes the possible strategies to mitigate icing problems from daily life and considers the importance of elasticity, slippery liquid-infused porous surfaces, amphiphilicity, antifreezing protein, organogels, and stimuli-responsive materials.
Abstract: Ice formation and accretion on surfaces is a serious economic issue in energy supply and transportation. Recent strategies for developing icephobic surfaces are intimately associated with superwettability. Commonly, the superwettability of icephobic materials depends on their surface roughness and chemical composition. This article critically categorizes the possible strategies to mitigate icing problems from daily life. The wettability and classical nucleation theories are used to characterize the icephobic surfaces. Thermodynamically, the advantages/disadvantages of superhydrophobic surfaces are discussed to explain icephobic behavior. The importance of elasticity, slippery liquid-infused porous surfaces (SLIPSs), amphiphilicity, antifreezing protein, organogels, and stimuli-responsive materials has been highlighted to induce icephobic performance. In addition, the design principles and mechanism to fabricate icephobic surfaces with superwettability are explored and summarized.
111 citations
TL;DR: Through electrodeposition, a stable, multiscale, cauliflower shaped fractal morphology was obtained and upon modification by stearic acid, the prepared coatings show extreme water repellency with contact angle of 162 ± 2° and roll-off angle of about 3°.
Abstract: Superhydrophobic surfaces have myriad industrial applications, yet their practical utilization has been limited by their poor mechanical durability and longevity. We present a low-cost, facile process to develop superhydrophobic copper-based coatings via an electrodeposition route, that addresses this limitation. Through electrodeposition, a stable, multiscale, cauliflower shaped fractal morphology was obtained and upon modification by stearic acid, the prepared coatings show extreme water repellency with contact angle of 162 ± 2° and roll-off angle of about 3°. Systematic studies are presented on coatings fabricated under different processing conditions to demonstrate good durability, mechanical and underwater stability, corrosion resistance, and self-cleaning effect. The study also presents an approach for rejuvenation of slippery superhydrophobic nature (roll-off angle <10°) on the surfaces after long-term water immersion. The presented process can be scaled to larger, durable coatings with controllabl...
104 citations
TL;DR: End-group modification of cellulose nanocrystals are performed by introducing hydrophobic chains (polystyrene) to CNC to yield amphiphilic nanoparticles that enhance the stability of emulsions.
Abstract: Sulfated cellulose nanocrystals (CNC) with high surface charge density are inadequate for stabilizing oil–water emulsions, which limits their applications as interfacial stabilizers. We performed end-group modification by introducing hydrophobic chains (polystyrene) to CNC. Results showed that the modified CNC are more effective in emulsifying toluene and hexadecane than pristine CNC. Various parameters were investigated, such as concentration of particles, electrolytes, and polarity of solvents on the characteristics of the emulsions. This study provides strategies for the modification of cellulose nanocrystals to yield amphiphilic nanoparticles that enhance the stability of emulsions. Such systems, bearing biocompatible and environmentally friendly characteristics, are attractive for use in a wide range of industries spanning food, biomedicine, pharmaceuticals, cosmetics, and petrochemicals.
103 citations
TL;DR: It is proposed that the peptidoglycan mesh in the bacterial wall is likely the primary target of the 2D nanomaterials, and the edges of the nanosheets were likely compromising the cell walls upon contact.
Abstract: Two-dimensional (2D) nanomaterials have attracted considerable attention in biomedical and environmental applications due to their antimicrobial activity. In the interest of investigating the primary antimicrobial mode-of-action of 2D nanomaterials, we studied the antimicrobial properties of MnO2 and MoS2, toward Gram-positive and Gram-negative bacteria. Bacillus subtilis and Escherichia coli bacteria were treated individually with 100 μg/mL of randomly oriented and vertically aligned nanomaterials for ∼3 h in the dark. The vertically aligned 2D MnO2 and MoS2 were grown on 2D sheets of graphene oxide, reduced graphene oxide, and Ti3C2 MXene. Measurements to determine the viability of bacteria in the presence of the 2D nanomaterials performed by using two complementary techniques, flow cytometry, and fluorescence imaging showed that, while MnO2 and MoS2 nanosheets show different antibacterial activities, in both cases, Gram-positive bacteria show a higher loss in membrane integrity. Scanning electron micro...
103 citations
TL;DR: There is a threshold surface charge density above which effective volume considerations are dominant across the concentration range relevant to liquid crystalline phase formation, and phase separation occurs at the same effective volume fraction of CNCs (∼10 vol %), with a corresponding increase in critical concentration due to the decrease in effective diameter that occurs with increasing surface charge.
Abstract: A series of four cellulose nanocrystal (CNC) suspensions were prepared from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liquid crystalline phase separation, but the concentration onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concentrations. The properties of the suspensions were interpreted in terms of the increase in effective diameter...
101 citations
TL;DR: It is demonstrated that the intracellular destination of nanoparticles beyond its ability to internalize is an important parameter that has to be accounted for in the design of targeted drug delivery systems.
Abstract: The role of nanoparticles in cancer medicine is vast with debate still surrounding the distinction between therapeutic efficacy of actively targeted nanoparticles versus passively targeted systems for drug delivery. While it is commonly accepted that methodologies that result in homing a high concentration of drug loaded nanoparticles to the tumor is beneficial, the role of intracellular trafficking of these nanoparticles in dictating the overall therapeutic outcome remains unresolved. Herein we demonstrate that the therapeutic outcome of drug loaded nanoparticles is governed beyond simply enabling nanoparticle internalization in cells. Using two model polymeric nanoparticles, one decorated with the GE11 peptide for active targeting of the epidermal growth factor receptor (EGFR) and the other without, we demonstrate that EGFR mediated intracellular internalization results in an enhanced therapeutic effect compared to the nontargeted formulation. Our findings demonstrate that the intracellular destination of nanoparticles beyond its ability to internalize is an important parameter that has to be accounted for in the design of targeted drug delivery systems.
TL;DR: The new homogeneous nanocatalyst, along with the mechanism proposed for its performance, may be very helpful for in-depth understanding of processes related to carbon dioxide electroreduction and conversion.
Abstract: Laser ablation in liquid was used to prepare homogeneous copper–zinc alloy catalysts that exhibited excellent selectivity for C2H4 in CO2 electroreduction, with faradaic efficiency values as high as 33.3% at a potential of −1.1 V (vs reversible hydrogen electrode). The high proximity of Cu and Zn atoms on the surface of the catalyst was found to facilitate both stabilization of the CO* intermediate and its transfer from Zn atoms to their Cu neighbors, where further dimerization and protonation occur to give rise to a large amount of ethylene product. The new homogeneous nanocatalyst, along with the mechanism proposed for its performance, may be very helpful for in-depth understanding of processes related to carbon dioxide electroreduction and conversion.
TL;DR: A dielectric-AgCl Janus micromotor that clearly moves away from the AgCl side when exposed to UV or strong visible light is developed and tentative explanations for its speed decay over time as well as its directionality are provided.
Abstract: Micromotors are an emerging class of micromachines that could find potential applications in biomedicine, environmental remediation, and microscale self-assembly Understanding their propulsion mechanisms holds the key to their future development This is especially true for a popular category of micromotors that are driven by asymmetric surface photochemical reactions Many of these micromotors release ionic species and are propelled via a mechanism termed “ionic self-diffusiophoresis” However, exactly how it operates remains vague To address this fundamental yet important issue, we have developed a dielectric-AgCl Janus micromotor that clearly moves away from the AgCl side when exposed to UV or strong visible light Taking advantage of numerical simulations and acoustic levitation techniques, we have provided tentative explanations for its speed decay over time as well as its directionality In addition, photoactive AgCl micromotors demonstrate interesting gravitactic behaviors that hint at three-dime
TL;DR: Interestingly, both kinetics and thermodynamic experiments show that emulsified oil adsorption on GA is a physical adsorptive and spontaneous process, demonstrating feasibility in practical applications of GA-based oily water treatment.
Abstract: A facile synthesis strategy was adopted to prepare resilient graphene aerogel (GA) with properties of high emulsified oil adsorption capacities, excellent rebounding performance, oil–water selectivity, and recycling abilities. The maximum adsorption capacity of GA for emulsified diesel oil was 2.5 × 104 mg g–1. The microscopic kinetic and thermodynamic mutual reaction models of diesel oil emulsion adsorption onto GA were investigated to describe the adsorption mechanism. The emulsified diesel oil was able to be separated efficiently from the oil–water emulsion by GA because of their high oil selectivity. Interestingly, both kinetics and thermodynamic experiments show that emulsified oil adsorption on GA is a physical adsorption and spontaneous process. Besides, GA can be reused with prominent repeatability for at least 10 cycles, demonstrating feasibility in practical applications of GA-based oily water treatment.
TL;DR: In this article, the effect of surface modification via silanization on protein adsorption/conformation and subsequent cell adhesion and spreading has been investigated, where self-assembled monolayers of five different surfaces (amine, octyl, mixed [1:1 ratio of amine:octyl], hybrid, and COOH) were characterized by Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, contact angle goniometry, profilometry, and field emission scanning electron microscopy (FESEM).
Abstract: Although metallic biomaterials find numerous biomedical applications, their inherent low bioactivity and poor osteointegration had been a great challenge for decades. Surface modification via silanization can serve as an attractive method for improving the aforementioned properties of such substrates. However, its effect on protein adsorption/conformation and subsequent cell adhesion and spreading has rarely been investigated. This work reports the in-depth study of the effect of Ti6Al4V surface functionalization on protein adsorption and cell behavior. We prepared self-assembled monolayers (SAMs) of five different surfaces (amine, octyl, mixed [1:1 ratio of amine:octyl], hybrid, and COOH). Synthesized surfaces were characterized by Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, contact angle goniometry, profilometry, and field emission scanning electron microscopy (FESEM). Quantification of adsorbed mass of bovine serum albumin (BSA) and fibronectin (FN) was determined on...
TL;DR: Two essential challenges, stable colloid formation and porosity retention, have been overcome to prepare MOF-based porous liquid and this porous liquid could provide a new material platform for liquid-bed-based gas separations.
Abstract: We reported an example of metal–organic framework (MOF)-based porous liquid by dispersing ZIF-8 ({Zn(mim)2}, mim = 2-methylimidazole) nanocrystallites in ionic liquid (IL) of [Bpy][NTf2] (N-butyl pyridinium bis(trifluoromethyl sulfonyl)imide). Two essential challenges, stable colloid formation and porosity retention, have been overcome to prepare MOF-based porous liquid. Preventing ZIF-8 nanocrystals from aggregation before dispersing is vital to form a stable ZIF-8 colloid in IL via enhancing the interaction between ZIF-8 and IL. The resultant ZIF-8–[Bpy][NTf2] colloid is able to be stable over months without precipitating. [Bpy][NTf2] with larger ion sizes cannot occupy pores in ZIF-8, leaving the ZIF-8 cage empty for enabling access by guest molecules. The porosity of this porous liquid system was verified by positron (e+) annihilation lifetime spectroscopy and I2 adsorption in ZIF-8 in the colloid. MOF-based porous liquids could provide a new material platform for liquid-bed-based gas separations.
TL;DR: It is demonstrated for the first time that W/O emulsions can be stabilized by using crystals from naturally occurring polyphenols (curcumin and quercetin particles) based on their size, microstructure, contact angle, interfacial tension, and ζ-potential measurements.
Abstract: In recent years, there has been a resurgence of interest in Pickering emulsions because of the recognition of the unique high steric stabilization provided by particles at interfaces. This interest is particularly keen for water-in-oil (W/O) emulsions because of the limited range of suitable Pickering stabilizers available. We demonstrate for the first time that W/O emulsions can be stabilized by using crystals from naturally occurring polyphenols (curcumin and quercetin particles). These particles were assessed based on their size, microstructure, contact angle, interfacial tension, and ζ-potential measurements in an attempt to predict the way that they act as Pickering stabilizers. Static light-scattering results and microstructural analysis at various length scales [optical microscopy, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM)] confirmed that the quercetin particles has a nearly perfect crystalline rod shape with a high aspect ratio; that is, the ratio of length ...
TL;DR: Compared with pristine MOF-derived carbon-based composites, the EM absorption ability of Co/TiO2-C was improved by multiple reflections between multilayered microstructures and the improved polarization loss and the strengthened conductivity loss caused by the carbon layers.
Abstract: Lightweight and compatible metal-organic framework (MOF)-derived carbon-based composites are widely used in electromagnetic (EM) absorption. Their combination with laminated TiO2-C (derived from Ti3C2T x) is expected to further strengthen the EM attenuation ability. Herein, novel laminated Co/TiO2-C hybrids were derived from Ti3C2T x/Co-MOF using heat treatment. Compared with pristine MOF-derived carbon-based composites, the EM absorption ability of Co/TiO2-C was improved by multiple reflections between multilayered microstructures and the improved polarization loss (due to the heterogeneous interfaces, residual defects, and dipole polarization) and the strengthened conductivity loss caused by the carbon layers. Specifically, for the Co/TiO2-C hybrids at thicknesses of 3.0 and 2.0 mm, the optimal reflection loss (RL) was -41.1 dB at 9.0 GHz and -31.0 dB at 13.9 GHz, with effective bandwidths (RL ≤ -10 dB) of 3.04 and 4.04 GHz, respectively. This study will underline the preparation of carbon-based absorbing materials starting from MXene/MOF hybrids.
TL;DR: It was observed that the blank nanoparticles showed no toxicity to HeLa cells, but DOX-loaded nanoparticles could inhibit the growth of tumor cells, and these composite nanoparticles displayed an effective near-IR photothermal conversion capability with a relatively high conversion efficiency.
Abstract: A pH- and ultrasound dual-responsive drug release pattern was successfully achieved using mesoporous silica nanoparticles (MSNs) coated with polydopamine (PDA). In this paper, the PDA shell on the MSN surface was obtained through oxidative self-polymerization under the alkaline condition. The morphology and structure of this composite nanoparticle were fully characterized by a series of analyses, such as infrared (IR), transmission electron microscopy, and thermogravimetric analysis. Doxorubicin hydrochloride (DOX)-loaded composite nanoparticles were used to study the performances of responsive drug storage/release behavior, and this kind of hybrid material displayed an apparent pH response in DOX releasing under the acidic condition. Beyond that, upon high-intensity focused ultrasound exposure, loaded DOX in composite nanoparticles was successfully triggered to release from pores because of the ultrasonic cavitation effect, and the DOX-releasing pattern could be optimized into a unique pulsatile fashion by switching the on/off status. From the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, it was observed that our blank nanoparticles showed no toxicity to HeLa cells, but DOX-loaded nanoparticles could inhibit the growth of tumor cells. Furthermore, these composite nanoparticles displayed an effective near-IR photothermal conversion capability with a relatively high conversion efficiency (∼37%). These as-desired drug delivery carriers might have a great potential for future cancer treatment that combine the chemotherapy and photothermal therapy.
TL;DR: The initial adsorption rates further reflect the change in interactions between the aggregates and these substrates caused by PEI, which follows the sequence of carboxyl > hydroxyl > alkyl > phenyl, which provides deep insights into the PDA/PEI co-deposition process on various substrates.
Abstract: Polydopamine-based chemistry has been employed for various surface modifications attributed to the advantages of universality, versatility, and simplicity. Co-deposition of polydopamine (PDA) with polyethyleneimine (PEI) has then been proposed to realize one-step fabrication of functional coatings with improved morphology uniformity, surface hydrophilicity, and chemical stability. Herein, we report the co-deposition kinetics related to the solution composition with different dopamine/PEI ratios, PEI molecular weights, dopamine/PEI concentrations, and the substrate surface with varying chemistry and wettability. The addition of PEI to dopamine solution suppresses the precipitation of PDA aggregates, resulting in an expanded time window of steady co-deposition compared with that of PDA deposition. Low-molecular-weight PEI at low concentration accelerates the co-deposition process, while high-molecular-weight PEI and high concentration of either PEI or dopamine/PEI are detrimental to the co-deposition effici...
TL;DR: A facile route to synthesize hierarchical nanotubular anatase/rutile/TiO2(B) nanostructures with high surface area and defective electronic structure is explored, demonstrating that defect modulation is a powerful tool to enhance the catalytic performances of TiO2-based photocatalysts.
Abstract: Oxygen vacancies have been demonstrated to enhance the interfacial charge separation in TiO2-based photocatalysts. In this report, we explored a facile route to synthesize hierarchical nanotubular anatase/rutile/TiO2(B) nanostructures with high surface area and defective electronic structure. The formation of oxygen vacancies in the heterophase junction was analyzed by UV-vis absorption spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The enhanced interfacial charge separation and transportation ensured the excellent photoactivity of oxygen-deficient junctions for the photocatalytic production of hydrogen. As a result, the defective anatase/rutile/TiO2(B) junction showed a high hydrogen evolution rate of 2.79 mmol/h, which was 19 times higher than blank TiO2 nanotubes. The results demonstrate that defect modulation is a powerful tool to enhance the catalytic performances of TiO2-based photocatalysts.
TL;DR: The structural memory effect of layered double hydroxides (LDHs) is one of the important reasons for their extensive use in environmental remediation, and humic acid (HA) was extracted from black soil and sediments and characterized to determine their structures.
Abstract: The structural memory effect of layered double hydroxides (LDHs) is one of the important reasons for their extensive use in environmental remediation. In this study, humic acid (HA) was extracted from black soil and sediments and characterized to determine their structures. The regeneration mechanisms of calcinated LDHs (CLDHs) including different divalent metals (Mg-CLDH and Zn-CLDH) in deionized water and different HA solutions were carefully elucidated, and the reasons for the behavior differences in the two materials were explained. The presence of the HAs significantly increased the dissolution rate of Mg2+ ions from Mg-CLDHs and subsequent regeneration of Mg-LDH. Because of the diverse functional groups in the HAs, these groups were complexed with metallic ions such as Mg2+ on the surface of Mg-CLDH in the beginning. During the process, the HAs adsorbed the regenerated LDHs on the surfaces. Therefore, the crystallinity, morphology, and specific surface area of the regenerated Mg-LDH significantly ch...
TL;DR: The formation of the monolayer polymer inside mesoporous oxide channels represents a method for the development of highly promising functional nanocomposites.
Abstract: Polymer/inorganic nanocomposites exhibit special properties due to highly intimate interactions between organic and inorganic phases and thus have been deployed for various applications. Among them, nanocomposites with monolayer polymer coverage on the inorganic surface demonstrate the highest efficiency for applications. However, the controllable synthesis of the polymer monolayer in mesopores of inorganic substrates remains a challenge. In this study, poly(acrylic acid)/γ-alumina nanocomposites (PAA/alumina) were synthesized via the in situ polymerization of acrylic acid impregnated in mesopores of alumina. By applying the preneutralization of monomers, the polymerization was found to be highly controllable in generating monolayer PAA coverage. The formation of monolayers was verified by thermogravimetry, semiquantitative Fourier transform infrared spectroscopy, N2 adsorption–desorption, and Pb(II) adsorption. Alternatively, the organic loadings of PAA/alumina composite samples could be controlled in th...
TL;DR: A simple method to fabricate the underwater superoleophobic and underoil superhydrophobic brass mesh via the nanosecond laser ablation is reported for the first time, which provided the micro-/nanoscale hierarchical structures.
Abstract: Materials with special wettability have drawn considerable attention especially in the practical application for the separation and recovery of the oily wastewater, whereas there still remain challenges of the high-cost materials, significant time, and complicated production equipment. Here, a simple method to fabricate the underwater superoleophobic and underoil superhydrophobic brass mesh via the nanosecond laser ablation is reported for the first time, which provided the micro-/nanoscale hierarchical structures. This mesh is superhydrophilic and superoleophilic in air but superoleophobic under water and superhydrophobic under oil. On the basis of the special wettability of the as-fabricated mesh, we demonstrate a proof of the light or heavy oil/water separation, and the excellent separation efficiencies (>96%) and the superior water/oil breakthrough pressure coupled with the high water/oil flux are achieved. Moreover, the nanosecond laser technique is simple and economical, and it is advisable for the ...
TL;DR: It was found that physical immobilization of chitosan allows to obtain hybrid composites (ChS) with a homogeneous distribution of polymer on the surface, relatively wide pores, and specific surface area of about 170 m2/g, and physical adsorption showed that physically adsorbed chitOSan on a silica surface has a higher sorption capacity.
Abstract: In this study, the influence of the chitosan immobilization method on the properties of final hybrid materials was performed. Chitosan was immobilized on the surface of mesoporous (ChS2) and fumed silica (ChS3) by physical adsorption and the sol–gel method (ChS1). It was found that physical immobilization of chitosan allows to obtain hybrid composites (ChS) with a homogeneous distribution of polymer on the surface, relatively wide pores, and specific surface area of about 170 m2/g, pHPZC = 5.7 for ChS3 and 356 m2/g and pHPZC = 6.0 for ChS2. The microporous chitosan–silica material with a specific surface area of 600 m2/g and a more negatively charged surface (pHPZC = 4.2) was obtained by the sol–gel reaction. The mechanisms of azo dye adsorption were studied, and the correlation with the composite structure was distinguished. The generalized Langmuir equation and its special cases, that is, Langmuir–Freundlich and Langmuir equations, were applied for the analysis of adsorption isotherm data. The adsorptio...
TL;DR: It is shown that an intermediate stage of self-assembly, between phase separation and gel vitrification, called tactoid annealing, helps explain the discrepancies in order for chiral nematic CNC films dried at varying evaporation times.
Abstract: The self-assembly process in cellulose nanocrystal (CNC) film formation was studied as a function of evaporation time. It is known that the total evaporation time of CNC dispersions affects the structure of the film obtained, but the extension of different phases of the evaporation has not been explored. By extending the evaporation time of CNC suspensions after the onset of liquid crystallinity, the homogeneity of the resulting films could be improved as observed by polarized optical microscopy and scanning electron microscopy. Here, we show that an intermediate stage of self-assembly, between phase separation and gel vitrification, called tactoid annealing, helps explain the discrepancies in order for chiral nematic CNC films dried at varying evaporation times. This intermediate stage of self-assembly may be useful for designing highly ordered and homogenous CNC-based materials.
TL;DR: This study links the topology of the network organization in space to its nonlinear rheological response preceding yielding and damage: this analysis elucidates how the network connectivity alone could be used to modify the gel mechanics at large strains, from strain-softening to hardening and even to a brittle response.
Abstract: The structural complexity of soft gels is at the origin of a versatile mechanical response that allows for large deformation, controlled elastic recovery, and toughness in the same material. A limit to exploiting the potential of such materials is the insufficient fundamental understanding of the microstructural origin of the bulk mechanical properties. Here we investigate the role of the network topology in a model gel through 3D numerical simulations. Our study links the topology of the network organization in space to its nonlinear rheological response preceding yielding and damage: our analysis elucidates how the network connectivity alone could be used to modify the gel mechanics at large strains, from strain-softening to hardening and even to a brittle response. These findings provide new insight for smart material design and for understanding the nontrivial mechanical response of a potentially wide range of technologically relevant materials.
TL;DR: This work designs submillimeter superhydrophobic ridges and shows that impacting droplets bounce off the surface immediately after capillary emptying in a petal-like shape at a certain Weber number range, and demonstrates that the petal bouncing is attributed to the synergistic cooperation of the hierarchical structures and anisotropic property, which endows effective energy storage and release.
Abstract: A droplet impacting on a superhydrophobic surface exhibits complete bouncing. The impacting process usually consists of spreading and retracting stages, during which the droplet contacts the underlying substrate. Recent research has been devoted to reducing the contact time using textured surfaces with different morphologies or flexibilities. Here, we design submillimeter superhydrophobic ridges and show that impacting droplets bounce off the surface immediately after capillary emptying in a petal-like shape at a certain Weber number range. The absence of a horizontal retraction process in two directions leads to ∼70% reduction in contact time. We demonstrate that the petal bouncing is attributed to the synergistic cooperation of the hierarchical structures and anisotropic property, which endows effective energy storage and release. When touching the bottom of the grooves, obvious flying wings appear along the ridges with a velocity component in the vertical direction, which help the energy releasing proc...
TL;DR: Results indicate that this kind of multifunctional bioinspired slippery surface, with superb stability, good cost effectiveness, and easy fabrication, can be used as a promising candidate for anti-icing and deicing applications.
Abstract: High durability, low cost, and superior anti-icing and active deicing multifunctional surface coatings, especially in the extreme environment, are highly desired to inhibit and/or eliminate the detriment of icing in many fields, such as automobile, aerospace, and power transmission. Herein, we first report a facile and versatile strategy to prepare novel slippery polyols-infused porous surfaces (SPIPS’s) with the inexpensive polyols as the lubricant liquids. These SPIPS’s are fabricated by a spray-coating approach based on amino-modified magnetic Fe3O4 nanoparticles (MNP@NH2) and amphiphilic P(poly(ethylene glycol) methyl ether methacrylate-co-glycidyl methacrylate) copolymer covalent cross-linked hybrids, followed by infusion with various polyols. The as-prepared surface exhibits excellent antifrosting property, that is, it can greatly postpone frost formation as long as 2700 s at −18 °C. Meanwhile, differential scanning calorimetry results clearly demonstrate that SPIPS’s show a remarkable freezing poin...
TL;DR: The in-depth study on the kinetics of graphene localization in this work provides a general guideline for the kinetic control of the localization of platelike nanofillers in polymer blends and demonstrates a facile method for manufacturing conductive polymer blends with low percolation thresholds.
Abstract: Selective localization of graphene in co-continuous polymer blends is an attractive method for preparing conductive polymer composites. Localization of graphene at the interface between the two polymer phases produces good conductivity at ultra-low concentrations. Although graphene localization is ultimately dependent on thermodynamic factors such as the surface energy of graphene and the two polymer components, kinetics also strongly affects the migration and localization of graphene in polymer blends during melt compounding. However, few studies have systemically investigated the important role of kinetics on graphene localization. Here, we introduced graphene nanoplatelets (GNPs) in polylactic acid (PLA)/polystyrene (PS) co-continuous polymer blends. Although GNPs in thermal equilibrium prefer the PS phase, we were able to kinetically trap GNPs at the interface of polymer blends via control of melt-compounding sequences, mixing times and shear rates. Utilizing morphological, rheological, and electrical...