Hydrophobic Materials Research Articles

Evaluation of Ibuprofen Prolonged Release of Biomedical PLA-PEG-PLA Hydrogel via Degradation Mechanism.

A micellar hydrogel has long been considered an intelligent hydrophobic drug delivery material. In this study, synthesized PLA1750-PEG1750-PLA1750 micellar hydrogel aims to encapsulate ibuprofen (IBU) in the core PLA hydrophobic of the micelle and prolong the drug release time by an injectable route. The structure and morphology of the PLA1750-PEG1750-PLA1750 copolymer hydrogel were demonstrated by 1H NMR and TEM data. The hydrogel also achieved a gel state at a high concentration of 25 wt.% under the physiological conditions of the body (37°C, pH 7.4). Besides, the biocompatibility test displayed that the hydrogel slightly affected mice after injection one week and fully recovered after four weeks. Furthermore, the in vitro degradation of the hydrogel showed apparent gel erosion after the first three weeks, which is related to the IBU release rate: slow for the first three weeks and then fast. As a result, the total drug release after three and four weeks was 18 wt.% and 41 wt.%, respectively. However, in the first 24 hours, the amount of the drug released was 10 wt.%, suggesting that the IBU drug diffused from the surface hydrogel to the buffer solution. These show that PLA1750-PEG1750-PLA1750 hydrogel can be a potential IBU drug delivery candidate.

Paper material coated with soybean residue nanocellulose waterproof agent and its application in food packaging

The increased use of petroleum-based plastics as food packaging materials has led to serious problems due to its non-biodegradability. This study discussed the feasibility of preparing hydrophobic paper packaging materials using soybean residue nanocellulose as coating. A hydrophobic coating with soybean residue nanocellulose waterproof agent was prepared by chemical modification, and super hydrophobic coated paper was prepared by coating technology. The results show that the water contact angle of the coated paper is greater than 150°, and it has excellent wear resistance and mechanical properties. When the waterproof coated paper is folded repeatedly, the water contact angle of the material does not change significantly at high and low temperatures or other adverse means, indicating that it has certain stability. Soaking in daily common drinks will not affect its waterproof property, so this material provides a foundation for the development of liquid packaging and provides a feasibility for the production of green degradable waterproof agent.

Theoretical and experimental investigations of an integrated rainwater harvesting system for electricity and drinking water.

Most of the electricity at present is generated from hydrocarbons like coal and gas. Their combustion is polluting the environment and raising the global temperature. Hence, there is an enhancement in catastrophes like floods, tornados, and droughts. Consequently, some part of the Earth is sinking, whereas there is a dearth of drinking water in some other part. A tribo-generator-integrated rainwater harvesting system for electricity and drinking purposes is proposed in the present paper to address these issues. A setup of the generating section of the scheme is developed and experimented in the laboratory. The obtained results show that the triboelectricity from rainwater depends on the rate of droplets falling per unit time, the height from which they are descending, and the coverage area of hydrophobic material. When released from 96cm, the low- and high-intense rain generates 67.9 and 189mV, respectively. Conversely, the electricity from the nano-hydro generator is proportional to the flow rate of water. 71.8mV is observed at an average flow rate of 49.05ml/s.

Large-Area Metal-Semiconductor Heterojunctions Realized via MXene-Induced Two-Dimensional Surface Polarization.

Direct MXene deposition on large-area 2D semiconductor surfaces can provide design versatility for the fabrication of MXene-based electronic devices (MXetronics). However, it is challenging to deposit highly uniform wafer-scale hydrophilic MXene films (e.g., Ti3C2Tx) on hydrophobic 2D semiconductor channel materials (e.g., MoS2). Here, we demonstrate a modified drop-casting (MDC) process for the deposition of MXene on MoS2 without any pretreatment, which typically degrades the quality of either MXene or MoS2. Different from the traditional drop-casting method, which usually forms rough and thick films at the micrometer scale, our MDC method can form an ultrathin Ti3C2Tx film (ca. 10 nm) based on a MXene-introduced MoS2 surface polarization phenomenon. In addition, our MDC process does not require any pretreatment, unlike MXene spray-coating that usually requires a hydrophilic pretreatment of the substrate surface before deposition. This process offers a significant advantage for Ti3C2Tx film deposition on UV-ozone- or O2-plasma-sensitive surfaces. Using the MDC process, we fabricated wafer-scale n-type Ti3C2Tx-MoS2 van der Waals heterojunction transistors, achieving an average effective electron mobility of ∼40 cm2·V-1·s-1, on/off current ratios exceeding 104, and subthreshold swings of under 200 mV·dec-1. The proposed MDC process can considerably enhance the applications of MXenes, especially the design of MXene/semiconductor nanoelectronics.

Experimental investigation on the effect of alkaline environment on the mechanical properties of aggregate rock

Aggregate generation from waste rock materials is an effective measure to solve the problem of waste disposal and reduce the high cost of concrete engineering materials. The aim of this study was to explore effects of hydrochemistry on the physical, mechanical, and fatigue properties of aggregate red sandstone and to evaluate the fatigue damage mechanisms. Red sandstone samples were immersed in NaOH solution. The NaOH crystals precipitated to produce hydrophobic white material to fill the internal pores, thus increasing the internal density of red sandstone. The chemical reaction caused reduction in the contents of minerals. The two processes occurred simultaneously and exhibited a competitive relationship. The mass change rate, P-wave velocity, compressive elasticity modulus, and compressive strength of the specimen increased with the increase in NaOH concentration. The tensile strength and Mode I fracture toughness initially increased and then decreased with the increase in NaOH concentration. The sample lost its strength after immersion in 20 mol/L NaOH. Dynamic mechanical analysis showed that the temperature increase led to moisture dissipation below the temperature threshold, which increased the energy storage modulus. The microstructure of red sandstone became loosely arranged under the dissolution effect of NaOH. Needle-like crystals were attached to the surface of sandstone particles, and the surface of particles become rough. The bending fatigue deflection-time curve exhibited a three-stage variation pattern. The fatigue life initially increased and then decreased with increase in NaOH concentration. An inverted S-shaped damage evolution model was developed with the residual deflection as the damage factor associated with the initial damage of chemical immersion, and the model was consistent with the experimental results.

Kneading-Dough-Inspired Quickly Dispersing of Hydrophobic Particles into Aqueous Solutions for Designing Functional Hydrogels.

Hydrogels containing hydrophobic materials have attracted great attention for their potential applications in drug delivery and biosensors. This work presents a kneading-dough-inspired method for dispersing hydrophobic particles (HPs) into water. The kneading process can quickly mix HPs with polyethyleneimine (PEI) polymer solution to form "dough", which facilitates the formation of stable suspensions in aqueous solutions. Combining with photo or thermal curing processes, one type of HPs incorporated PEI-polyacrylamide (PEI/PAM) composite hydrogel exhibiting good self-healing ability, tunable mechanical property is synthesized. The incorporating of HPs into the gel network results in the decrease in the swelling ratio, as well as the enhancement of the compressive modulus by more than five times. Moreover, the stable mechanism of polyethyleneimine-modified particles has been investigated using surface force apparatus, where the pure repulsion during approaching contributes to the good stability of the suspension. The stabilization time of the suspension is dependent on the molecular weight of PEI: the higher the molecular weight is, the better the stability of the suspension will be. Overall, this work demonstrates a useful strategy to introduce HPs into functional hydrogel networks. Future research can be focused on understanding the strengthening mechanism of HPs in the gel networks.

Rational design of pyrrolic-N dominated carbon material derived from aminated lignin for Zn-ion supercapacitors

Developing highly efficient, sustainable carbon cathodes is essential for emerging Zn-ion hybrid supercapacitors (ZICs). Herein, lignin's novel chemical modification (amination) has been developed to produce high quantity pyrrolic-N moieties as active sites. Furthermore, chemically modified amine moieties in lignin are vital as a natural self-activating template to generate hierarchical porosity in the 2D (graphene-like) architecture with exceedingly high surface area (2926.4 m2g−1). The rationally introduced dominated pyrrolic-N moieties boost the Zn-ion storage capacity and reaction kinetics due to the dual energy storage mechanism and efficient charge transfer between pyrrolic-N and Zn+2 ions. Furthermore, the pyrrolic-N species are energetically favorable for the adsorption of Zn+2 ions by the formation of N-Zn+2 chemical bonds. Besides, the nitrogen oxides reduce the intrinsic resistance and induce a more polarized surface, resulting in high wettability and efficient transfer of electrolytes into the pores of hydrophobic carbon materials. Subsequently, the chemically modified lignin-derived activated carbon material (Chem-ACM) as a cathode in ZICs delivers a high capacity of 161.2 mA h g−1 at 1 A g−1 with the admirable energy density of 106.7 W h kg−1 at 897 W kg−1 and excellent retention capacity (94%) after 10,000 cycles. Mainly, the assembled quasi solid-state ZICs using Chem-ACM retains the remarkable storage capacity (202 mA h g−1 at 0.2 Ag−1) even at a high bending angle. Notably, the Chem-ACM has been further employed in symmetric supercapacitors as an electrode, and it displays exceptional specific capacitance of 354 Fg−1 at 0.5 Ag−1 with tremendous energy (43.5 W h kg−1) and the power density (0.53 kW kg−1). Additionally, the charge storage capability of Chem-ACM is positively dependent on high nitrogen contents, and it is extrapolated that pyrrolic-N moieties are dominant active sites. Hence, the designed amination-assisted biocarbon synthesis provides a new way to prepare high nitrogen-containing biocarbon for ZICs and further understand pyrrolic-N species' impact on Zn-ion storage.

Surface-bubble-modulated liquid chromatography: an experimental strategy for identification of molecular processes of solute retention in reversed-phase separation systems.

Molecular level understanding of the chemistry at the aqueous/hydrophobe interface is crucial to separation processes in aqueous media, such as reversed-phase liquid chromatography (RPLC) and solid-phase extraction (SPE). Despite significant advances in our knowledge of the solute retention mechanism in these reversed-phase systems, direct observation of the behavior of molecules and ions at the interface in reversed-phase systems still remains a major challenge and experimental probing techniques that provide the spatial information of the distribution of molecules and ions are required. This review addresses surface-bubble-modulated liquid chromatography (SBMLC), which has a stationary gas phase in a column packed with hydrophobic porous materials and enables one to observe the molecular distribution in the heterogeneous reversed-phase systems consisting of the bulk liquid phase, the interfacial liquid layer, and the hydrophobic materials. The distribution coefficients of organic compounds referring to their accumulations onto the interface of alkyl- and phenyl-hexyl-bonded silica particles exposed to water or acetonitrile-water and into the bonded layers from the bulk liquid phase are determined by SBMLC. The experimental data obtained by SBMLC show that the water/hydrophobe interface exhibits an accumulation selectivity for organic compounds, which is quite different from that of the interior of the bonded chain layer, and the overall separation selectivity of the reversed-phase systems is determined by the relative sizes of the aqueous/hydrophobe interface and the hydrophobe. The solvent composition and the thickness of the interfacial liquid layer formed on octadecyl-bonded (C18) silica surfaces are also estimated from the bulk liquid phase volume determined by the ion partition method employing small inorganic ions as probes. It is clarified that various hydrophilic organic compounds as well as inorganic ions recognize the interfacial liquid layer formed on the C18-bonded silica surfaces as being different from the bulk liquid phase. The behavior of some solute compounds exhibiting substantially weak retention in RPLC or the so-called negative adsorption, such as urea, sugars, and inorganic ions, can rationally be interpreted with a partition between the bulk liquid phase and the interfacial liquid layer. The spatial distribution of solute molecules and the structural properties of the solvent layer on the C18-bonded layer determined by the liquid chromatographic methods are discussed in comparison to the results obtained by other research groups using molecular simulation methods.

New Functional Polymer Materials via Click Chemistry-Based Modification of Cellulose Acetate.

Cellulose acetate (CA) was partially acrylated, and the resulting cellulose acetate acrylate (acryl-substitution degree of 0.2) underwent quantitative thio-Michael click reactions with various thiols. A toolbox of functional CA polymers was obtained in this way, and their properties were studied. The modification with fatty alkyl thiols led to hydrophobic materials with large water drop contact angles. Octadecylthio-, butoxycarbonylpropylthio-, and furanylthio-modifications formed highly transparent materials. The new derivative CAASFur disintegrated completely under industrial composting conditions. Films of modified CA polymers were cast and investigated in terms of barrier properties. The nanocomposite of CAAS18 compounded with a synthetic layered silicate (hectorite) of a large aspect ratio showed permeabilities as low as 0.09 g mm m-2 day-1 for water vapor and 0.16 cm3 mm m-2 day-1 atm-1 for oxygen. This portfolio of functional CA polymers opens the door to new applications.

Robust and hydrophobic interlayer material for efficient and highly stable organic solar cells

Robust and hydrophobic interlayer material for efficient and highly stable organic solar cells

Maximising olive oil by‐products

Maximising olive oil by‐products

Fabrication of a novel polyurethane foam-alginate-zeolite hydrogel and subsequent KSND bacteria encapsulation: evidence of accelerated biofilm colonization and enhanced nitrogen removal efficiency.

Biofilms are used widely to remove nitrogen from wastewater; however, most biofilm carriers (i.e. polyurethane foam, PUF) are hydrophobic organic materials with millimetre-scale apertures, ineffective attachment, and unstable colonization of microorganisms. To address these limitations, hydrophilic sodium alginate (SA) mixed with zeolite powder (Zeo) was cross-linked in PUF to form a micro-scale hydrogel (PAS) with a well-organized and reticular cellular structure. Scanning electron microscopy revealed that immobilized cells were entrapped in the interior of hydrogel filaments and rapidly formed a stable biofilm on the surface. The biofilm generated was 10.3-fold greater than the film developed on PUF. Kinetics and isotherm studies revealed that the as-developed carrier, because of the presence of Zeo, effectively improved the adsorption of NH4+-N by 53%. The PAS carrier achieved total nitrogen removal in excess of 86% for low carbon-to-nitrogen ratio wastewater treated for 30 d, indicating that this novel modification-encapsulation technology has potential for wastewater treatment.

Design and modeling of corneal aberration correction with diffractive IOL based on ZEMAX

This paper estimates a specific detailed diffractive aspheric bifocal intraocular lens (IOL) used to correct and reduce corneal aberration and a patient’s standard surgical implantation. Foldable acrylic hydrophobic materials have promising properties and are thus used in IOLs. Calculations and analyses were performed using the optical software design program Zemax, and important criteria, such as modulation transfer function and Seidel aberration, were tested over a range of fields of view (20°, 30° or 40°) and different values of entrance pupil diameter (1.5, 3 and 4 mm). Results showed that a significant amount of corneal spherical aberration can be compensated for. The diffractive hydrophobic IOL customizes and corrects the spherical aberration performance of the individual crystalline lens.

Morphological Behavior of Liposomes and Lipid Nanoparticles.

Liposomes, which consist of bilayer lipids surrounding interior aqueous compartment(s), were first characterized nearly 60 years ago. Remarkably, many fundamental properties of liposomes and their micellar-like "solid core" counterparts (a lipid monolayer surrounding a hydrophobic core) and transitions between these structures remain poorly understood. In this work, we examine the effects of basic variables on the morphology adopted by lipid-based systems produced by rapid mixing of lipids in ethanol with aqueous media. We show that, for lipids such as distearolyphosphatidylcholine (DSPC)-cholesterol mixtures that form bilayer vesicles on hydration, osmotic stress can induce regions of high positive membrane curvature, leading to fusion between unilamellar vesicles to produce bilamellar vesicles. Addition of lyso PC, an "inverted cone"-shaped lipid that supports regions of high positive curvature, can inhibit the formation of these bilamellar vesicles by stabilizing a hemifused intermediate structure. Conversely, the presence of "cone"-shaped lipids such as dioleoylphosphatidylethanolamine (DOPE) that results in negative membrane curvature promotes fusion events subsequent to vesicle formation (during the ethanol dialysis stage), leading to bilamellar and multilamellar systems even in the absence of osmotic stress. Alternatively, the presence of increasing amounts of triolein, a lipid that is insoluble in lipid bilayers, results in increasing internal solid core structures until micellar-like systems with a hydrophobic core of triolein are achieved. These results are interpreted in terms of the intrinsic membrane curvature that bilayer vesicles can stably maintain as well as the ability of bilayer lipids to first form a monolayer around a solid core of hydrophobic material such as triolein and then, as the proportion of bilayer lipids is increased, progressively form bilayer structures that can eventually form a complete bilayer encapsulating both a hydrophobic core and an aqueous compartment. These hybrid intermediate structures may have utility as novel drug delivery systems.

A facile strategy to fabricate antibacterial hydrophobic, high-barrier, cellulose papersheets for food packaging

As a traditionally used packaging material, natural cellulose-based paper has poor barrier properties to water and oxygen, which severely limits its wide application in food packaging. In this study, we report a new sustainable approach to producing hydrophobic, high-barrier, and antibacterial packaging materials from cellulose paper. In this process, commercially available microcrystalline cellulose was first modified by long-chain stearic acid to form hydrophobic microcrystalline cellulose ester and then mixed with stearic acid as filler in the subsequent surface coating of bagasse fibre paper. The microcrystalline cellulose ester/stearic acid-coated paper (MSP) exhibited good water repellency and oxygen barrier activity due to a continuous hydrophobic film that formed, which completely covered the pores of the original bagasse fibre paper. The coated MSP sample also showed excellent dimensional stability in water and a good wet tensile strength of 16 MPa. In addition, poly(hexamethylene guanidine) (PHMG) was chemically grafted onto the free carboxyl groups of the MSP surface layer, and the resulting MSP-g-PHMG samples exhibited excellent antibacterial activity against Escherichia coli and Listeria monocytogenes. The biodegradable cellulose-based MSP-g-PHMG sample significantly delayed the decay of raspberry during storage, indicating its potential application in food packaging.

Scaled-Up Synthesis of Freestanding Molybdenum Disulfide Membranes for Nanopore Sensing.

2D materials are ideal for nanopores with optimal detection sensitivity and resolution. Among these, molybdenum disulfide (MoS2 ) has gained traction as a less hydrophobic material than graphene. However, experiments using 2D nanopores remain challenging due to the lack of scalable methods for high-quality freestanding membranes. Herein, a site-directed, scaled-up synthesis of MoS2 membranes on predrilled nanoapertures on 4-inch wafer substrates with 75% yields is reported. Chemical vapor deposition (CVD), which introduces sulfur and molybdenum dioxide vapors across the sub-100 nm nanoapertures results in exclusive formation of freestanding membranes that seal the apertures. Nucleation and growth near the nanoaperture edges is followed by nanoaperture decoration with MoS2 , which proceeds until a critical flake curvature is achieved, after which fully spanning freestanding membranes form. Intentional blocking of reagent flow through the apertures inhibits MoS2 nucleation around the nanoapertures, promoting the formation of large-crystal monolayer MoS2 membranes. The in situ grown membranes along with facile membrane wetting and nanopore formation using dielectric breakdown enables the recording of dsDNA translocation events at an unprecedentedly high 1 MHz bandwidth. The methods presented here are important steps toward the development of scalable single-layer membrane manufacture for 2D nanofluidics and nanopore applications.

Nanofluidic Attenuation of Metal-Organic Frameworks

Porous materials with energy absorption characteristics have been used for attenuation against hazardous vibrations and noises. The intrusion of liquid water and aqueous solutions into hydrophobic nanoporous materials such as metal-organic frameworks (MOFs) present an attractive pathway to engineering new attenuation technologies. In this process, hydrostatic pressure forces water to intrude hydrophobic nanopores, thereby converting mechanical work into interfacial energy through nanoscale interfacial interactions. Once the external pressure is removed, water molecules can flow out of the nanopores spontaneously, making the system reversible. We envision that this mechanism has the potential of innovating attenuation technologies, so in this work we provided a preliminary study in this direction. We investigated a material system consisting of water and a commonly used MOF, zeolitic imidazolate framework-8 (ZIF-8), and demonstrated its reversibility and stability under cyclic pressurization, considered its performance at various peak pressures and frequencies, its tunability in terms of intrusion pressure, and its potential in hydrogel forms. These features are important for potential attenuation technologies based on this novel mechanism.

Гидрофобизация пленок целлюлозы, полученной из стебля борщевика Сосновского, растворами теломеров тетрафторэтилена

The process of obtaining cellulose from the Sosnowsky hogweed stem and spathellas from this cellulose is described in detail. The task is relevant from the point of view of the use of this weed. The elemental composition and properties of the obtained cellulose samples were studied by elemental analysis, infrared (IR) spectroscopy, X-ray powder diffractometry, differential scanning calorimetry (DSC), and X-ray photoelectron spectroscopy (XPS). The study of IR spectra and X-ray patterns of cellulose made it possible to determine the degree of its crystallinity (65…75 %). The glass transition temperature (105…108 °C) of the samples was estimated from the results of DSC. A comparative analysis of the characteristics of the obtained cellulose with the available literature data was carried out. The treatment of spathellas obtained from cellulose with solutions of radiation-synthesized tetrafluoroethylene (TFE) telomers made it possible to obtain a hydrophobic material with a contact angle exceeding 140°. For hydrophobization, we used TFE telomers synthesized in acetone, the binary solvent Freon 113 + ammonia, and Flutec PP3, which have different terminal groups. It has been established that the interfacial angle of the surface of a cellulose spathella treated with telomers depends both on the composition (end groups) of the telomer and on the initial concentration of TFE at which the synthesis was carried out. The optimal concentration of TFE for the synthesis of telomers in Flutec PP3 has been determined. The presence of a fluoropolymer coating of the spathella, which ensures its hydrophobicity, was confirmed by XPS results.

Rational construction of multifunctional hydrophilic coatings with sustainable anti-fogging, UV-shielding and anti-freezing abilities

Special wettability endows surface anti-fogging performance on transparent substrates by promoting filmwise condensation via hydrophilic materials or preventing water adhesion via hydrophobic materials. However, the harsh environments associated with low temperature and mechanical loads restrict their anti-fogging persistence. In this work, a hydrophilic coating with long-lasting anti-fogging, anti-freezing, and anti-aging properties was rationally prepared by constructing a double-layer structure. The bottom layer (T coating) adopts a titanium dioxide coating obtained by hydrolysis of tetrabutyl titanate, which can act as a UV absorber and improve the UV-shielding property of the coating. The top layer (ZGS coating) is constructed of a cross-linked network structure with zein, gelatin, glucose and silica for anti-freezing and anti-fogging properties. The resulting coating (ZGST) can maintain excellent anti-fogging performance after placing in a hot fog environment (100℃) for 1 h, 300 cycles abrasion, 70 tape-peeling, 120 min ultrasonication and extended service time (261 days so for). One application of greenhouse films with anti-fogging performance was demonstrated, which can improve the status quo of agricultural film and has important significance for the field of agricultural development. It is anticipated that this work may offer valuable guidance for the preparation of anti-fogging, anti-freezing and UV resistant optical materials, which allows potential applications in vehicles, medical, agricultural or vision systems under extreme environments.

Benchmarking the Photocatalytic Self-Cleaning Activity of Industrial and Experimental Materials with ISO 27448:2009.

Various industrial surface materials are tested for their photocatalytic self-cleaning activity by performing the ISO 27448:2009 method. The samples are pre-activated by UV irradiation, fouled with oleic acid and irradiated by UV light. The degradation of oleic acid over time is monitored by taking water contact angle measurements using a contact angle goniometer. The foulant, oleic acid, is an organic acid that makes the surface more hydrophobic. The water contact angle will thus decrease over time as the photocatalytic material degrades the oleic acid. In this study, we argue that the use of this method is strongly limited to specific types of surface materials, i.e., only those that are hydrophilic and smooth in nature. For more hydrophobic materials, the difference in the water contact angles of a clean surface and a fouled surface is not measurable. Therefore, the photocatalytic self-cleaning activity cannot be established experimentally. Another type of material that cannot be tested by this standard are rough surfaces. For rough surfaces, the water contact angle cannot be measured accurately using a contact angle goniometer as prescribed by the standard. Because of these limitations, many potentially interesting industrial substrates cannot be evaluated. Smooth samples that were treated with an in-house developed hydrophilic titania thin film (PCT/EP2018/079983) showed a great photocatalytic self-cleaning performance according to the ISO standard. Apart from discussing the pros and cons of the current ISO standard, we also stress how to carefully interpret the results and suggest alternative testing solutions.