Hydrophilic Phase Research Articles

Polyepichlorohydrin grafted poly(phenylene oxide) to construct hydrophilic and hydrophobic microphase separation anion exchange membrane

An anion exchange membrane (QAPECH-g-PPO) with polyepichlorohydrin (PECH) as the main chain and poly(phenylene oxide) (PPO) as the side chain was prepared by Williamson etherification reaction. Atomic force microscopy (AFM) and small angle X-ray scattering (SAXS) characterization indicate that PECH grafted with PPO can effectively form a hydrophilic and hydrophobic phase separation structure. The amount of and molecular weight of PPO grafted has different effects on the membrane properties. As the amount of PPO grafted increases, the tensile strength of the membrane gradually increases. When the amount of PPO grafted exceeds 44%, the excessive hydrophobic phase prevents the formation of continuous ionic channels in the hydrophilic phase, leading to a significant decrease in ionic conductivity. When the amount of PPO is 38%, the ionic conductivity can reach 72 mS cm−1 (80 °C), while the swelling ratio is only 15%. Moreover, higher molecular weight PPO at 38% amount improves tensile strength of QAPECH-g-PPO membrane. The higher the molecular weight of PPO, the more stable the π - π stacking structure is formed, leading to more aggregation of hydrophobic phases in the anion exchange membrane and weakened constraints on ion clusters. Therefore, the water absorption and ion conductivity slightly increase.

Poly(aryl ether sulfone ketone) with densely sulfonated structural units facilitate microphase separation to promote proton transport

The development of high-performance and low-cost membrane materials is crucial for proton exchange membrane fuel cells. To improve the proton conductivity, we designed a novel multiple phenyls monomer. Then, we synthesize a series of sulfonated poly(aryl ether sulfone ketone) membranes (SPAESK-x). The hydrophilic groups are densely distributed in units after sulfonation, which can form large hydrophilic ion clusters and provide more connected channels for proton transport. The large hydrophilic ion clusters facilitate the separation of hydrophilic and hydrophobic phases to form wider proton transport channels. The SPAESK-15 membrane achieves a high proton conductivity (181.0 mS cm-1) at 80 °C. The novel monomer and polymers are budget and simple to synthesize, offering the possibility of large-scale preparation. Overall, the novel structure has the potential to develop high-performance electrolyte materials.

Morphology and Transport Study of Acid-Base Blend Proton Exchange Membranes by Molecular Simulations: Case of Chitosan/Nafion.

Blending a basic polymer (e.g., chitosan) with Nafion can modify some membrane properties in direct methanol fuel cell applications, e.g., controlling methanol crossover, by regulating the morphology of hydrophilic channels. Unraveling the mechanisms by which the channel morphology is modified is essential to formulate design strategies for acid-base blend membrane development. Thus, we use molecular simulations to analyze the morphological features of a blend membrane (at 75/25 chitosan/Nafion wt %), i.e., (i) water/polymer phase organizations, (ii) number and size of water clusters, and (iii) quantitative morphological measures of hydrophilic channels, and compare them to the pure Nafion in a wide range of water contents. It is found that the affinity of water to different hydrophilic groups in the blend membrane can result in more distorted and dispersed hydrophilic phase and fewer bulk water-like features compared to pure Nafion. Also, the width of the hydrophilic network bottleneck, i.e., pore limiting diameter (PLD), is found to be almost five times smaller for the blend membrane compared to Nafion at their maximum water contents. Moreover, by changing the chitosan/Nafion weight ratio from 75/25 to 0/100, we show that as Nafion content increases, all channel morphological characteristics alter monotonically except PLD. This is mainly due to the strong acid-base interactions between Nafion and chitosan, which hinder the monotonic growth of PLD. Interestingly, water and methanol diffusion coefficients are strongly correlated with PLD, suggesting that PLD can be used as a single parameter for tailoring the blending ratio for achieving the desired diffusion properties of acid-base membranes.

A method of predicting the two-phase liquid-liquid flow resistance in a horizontal pipe with a layer of metal foam

The study reported here is experimental. Its aim was to determine the method applicable for prediction of pressure losses of an unstable two-phase liquid-liquid system flow through a horizontal pipe with a short section of the pipe containing a metal foam packing. However, the flow disturbance resulting from the presence of foam does not lead to a change in the type of the mixture (as there is no phase inversion) nor a permanent emulsification of the flow system. The calculation procedure developed in the study takes into account both the peculiarities that accompany the flow of a two-phase liquid-liquid system in an empty pipe (i.e. type of continuous phase, phase slip, hold-up), as well as geometric parameters of the foam skeleton (i.e. cell and pore dimensions, surface roughness of fibers). The results of experimental research were applied for the purposes of determining the specific form of the equations, consistent with the mathematical model adopted and described in detail in this paper. They were conducted for two foams: aluminum and nickel, which were characterized by the same degree of pore packing (PPI20). The mean dimensions of the elements forming metal foams skeletons were determined by computed tomography. The horizontal flow tube had a diameter of 10 mm and the foam packing occupied it only over a a section with a certain length. In the liquid-liquid system pumped to the pipe, the hydrophilic phase was tap water, while the hydrophobic phase was typical machine oil. The adopted range of flux changes of both liquids corresponded to the conditions at which unstable two-phase systems of the W/O, O/W and W+O type were formed in the empty pipe. The pressure loss of the flowing substance was measured in the foam layer. The values of constants and exponents of the adopted model equation were determined separately for single-phase flow and two-phase systems of various types. The results of the statistical evaluation of the performance of the developed dependencies justify their application in the design procedures of selected heat or mass transfer devices. The equations are dimensionless, and therefore, under the conditions of validity, they should also be effective for other liquid-liquid systems, other foams and flow in a pipe with a different diameter. The developed method is based on a new approach to the description of the two-phase flow resistance through the porous material filling the pipe. In addition, it concerns the flow of a liquid-liquid system, which still forms the area that has been tackled in few publications.

Comprehensive understanding of oxygen transport at Gas/ionomer/electrocatalyst triple phase boundary in PEMFCs

Reducing Pt loading of proton exchange membrane fuel cells (PEMFCs) without sacrificing performance remains challenging due to the severe oxygen transport resistance in cathode, especially the local oxygen transport resistance (RLocal) at the gas/ionomer/electrocatalyst triple phase boundary (TPB). Here, the detailed oxygen adsorption mechanism at surface ionomer is quantified for the first time via a self-built characterization system based on quartz crystal microbalance (QCM). The results show that the surface oxygen adsorption amount quasi-logarithmically increases as oxygen partial pressure increases. The ionomer surface is further investigated by molecular dynamics simulations and it is found that there exists not only non-uniformity in morphology, but also separation of hydrophilic and hydrophobic phase, which leads an inhomogeneity of interaction with oxygen. As a consequence, the extended form of Toth model is proved to be more appropriate for the surface oxygen adsorption on ionomer film due to higher correlation coefficients R2, better applicability at low pressure and varying temperature. Ultimately, we successfully predict the oxygen adsorption amount and the corresponding trend of RLocal at practical fuel cell operating condition with the adsorption model disclosed in this work, which is potential to estimate the oxygen adsorption in other type of electrochemical devices.

Development of a new method for determination of bisphenol A based on stirrer-assisted switchable hydrophilic solvent-based liquid phase microextraction coupled with electrochemical sensor

In this work, a novel stirrer-assisted liquid-phase microextraction method using switchable hydrophilic solvents was developed for the extraction and preconcentration of bisphenol A from real samples prior to electrochemical analysis. For the first time, the effect of stirring while switching the extraction solvent (N,N-dipropylamine, DPA) was investigated, and the use of stirring instead of temperature change, which is a time-consuming process, hazardous acids (e.g., HCl), and dry ice was used for bisphenol A extraction based on switchable solvents. Various parameters such as solvent type, solvent volume, stirring time, and stirring speed were optimized. The optimized conditions were 100 μl DPA, 2 min extraction time, 30 s stirring time, 700 rpm stirring speed, and solution pH of 7.0. A theoretical study was also conducted to show the effects of stirring on the homogenization of the phases. The proposed method offers some advantages, such as simplicity, use of a small amount of inexpensive and less hazardous reagents, rapid extraction, and shorter analysis time. Under the optimized conditions for the developed method, LOQ and LOD were obtained to be 0.01 and 0.003 μM, respectively. Moreover, the calibration curves were linear in the range of 0.01–250 μM. The proposed method was used for the determination of bisphenol A in food and water samples.

Impact of the Membrane Structure of the Stationary Phase on Steric Exclusion Chromatography (SXC) of Lentiviral Vectors.

For steric exclusion chromatography (SXC), hydrophilic stationary phases are used to capture the target molecule in the presence of polyethylene glycol. The influence of the structure and pore size of the stationary phase on the process requirements are not yet well understood. To better understand the SXC process, membranes with different pore sizes that served as a stationary phase were compared for the purification of lentiviral vectors (LVs). A design of experiments (DoE) was performed to assess the combined impact of PEG concentration and membrane pore size on the purification performance. A visualization experiment showed that the LVs were captured on the first membrane layer for a pore size up to 2.2 µm, and for a pore size larger than 2.2 µm, LVs were also partly found on the second and third membrane layers. Moreover, we could observe that increasing membrane pore size requires a higher PEG concentration to achieve comparable LV recoveries. Using five membrane layers as a stationary phase was sufficient to achieve good performance, supporting the visualized capture results. In conclusion, we could show that each stationary phase has its optimal PEG buffer compositions for SXC, depending on the membrane structure and pore size.

Silica-Based Stationary Phase with Surface Bound N-Acetyl-glucosamine for Hydrophilic Interaction Liquid Chromatography.

A hydrophilic silica-based stationary phase with surface bound N-acetylglucosamine (GlcNAc-silica) was prepared in house and characterized physically via Fourier transform infrared (FTIR) analysis and thermogravimetric analysis (TGA) and chromatographically over a wide range of mobile phase compositions. While both FTIR and TGA confirmed the attachment of the GlcNAc ligands to the silica surface, the chromatographic evaluation of GlcNAc-silica with polar and slightly polar standard solutes (e.g., sugars, nucleic acid fragments, phenolic, and benzoic acid derivatives) yielded the typical hydrophilic interaction liquid chromatography (HILIC) behaviors in the sense that retention increased with increases in solute polarity and the organic content (i.e., acetonitrile) of the hydro-organic mobile phase (i.e., ACN-rich mobile phase). Sugars derivatized with 1-naphthylamine (1-NA) and 2-aminoanthrcene (2-AA) such as xylose, glucose, and short chains maltooligosaccharides constituted the most polar species for HILIC retention evaluation, and in addition, the maltooligosaccharides offered a polar homologous series for gauging the hydrophilicity of GlcNAc-silica in analogy with alkylbenzene homologous series and other nonpolar homologues for evaluating the hydrophobicity of non-polar stationary phases. On the other hand, the benzoic acid and phenolic acid derivatives were the probe solutes for evaluating the HILIC retention dependence of ionizable solutes on the pH of the mobile phase. Similarly, the nucleobase and nucleoside weak basic solutes as well as some typical cyclic nucleotide acidic solutes allowed for the examination of the dependence of solute retention on the pH of the mobile as well as the polarity of the species.

Physical properties with high specific loss power of magnetite (Fe3O4) synthesized via thermal decomposition technique

Magnetic iron oxide nanoparticles have versatile applications in biomedical science that require control over shape and size distribution. Thermal decomposition is one of the best methods for controlling the size and shape of produced nanoparticles (NPs). The size distribution can be tuned (5–30 nm) by varying the reaction environment such as precursor concentration, amount of solvent used, temperature ramp, and reflux time. Iron oleate was used as a precursor solution and heated up to reflux temperature (310 °C) for 10 min within the oxygen-free environment by applying N2 gas flow. The XRD pattern confirmed the formation of NPs with a crystallite size of 17 ± 2.45 nm. Transmission electron microscope images showed moderately cubic shapes with a mean particle size of 28.67 ± 7.12 nm. Magnetic properties such as saturation magnetization, coercivity, and remanence were calculated at 23.48 emu/gm, 33 Oe, and 0.6 emu/gm, respectively, which indicated the ferromagnetic nature of the NPs. The Verwey transition was identified from the magnetization vs temperature (FC-ZFC) plot. The bondings of the oleic acid surfactant with the produced NPs were confirmed from Fourier transformation infrared spectroscopy (FTIR) data analysis. For the application of hyperthermia, the hydrophobic phase was transferred to the hydrophilic phase using cetyltrimethylammonium bromide, which was assured by the FTIR data analysis. The hyperthermia heating of NPs was measured for different concentrations of NPs (0.25, 0.5, 1, 2, and 4 mg/ml), from which specific loss power (SLP) was calculated. Among them, 0.25 mg/ml produced the most prominent SLP (2149 ± 309 w/g) that can be applied for targeted cancer treatment.

Water-Induced Phase Separation for Anti-Swelling Hydrogel Adhesives in Underwater Soft Electronics.

The development of hydrogel-based underwater electronics has gained significant attention due to their flexibility and portability compared to conventional rigid devices. However, common hydrogels face challenges such as swelling and poor underwater adhesion, limiting their practicality in water environments. Here, a water-induced phase separation strategy to fabricate hydrogels with enhanced anti-swelling properties and underwater adhesion is presented. By leveraging the contrasting affinity of different polymer chains to water, a phase-separated structure with rich hydrophobic and dilute hydrophilic polymer phases is achieved. This dual-phase structure, meticulously characterized from the macroscopic to the nanoscale, confers the hydrogel network with augmented retractive elastic forces and facilitates efficient water drainage at the gel-substrate interface. As a result, the hydrogel exhibits remarkable swelling resistance and long-lasting adhesion to diverse substrates. Additionally, the integration of carboxylic multiwalled carbon nanotubes into the hydrogel system preserves its anti-swelling and adhesion properties while imparting superior conductivity. The conductive phase-separated hydrogel exhibited great potential in diverse underwater applications, including sensing, communication, and energy harvesting. This study elucidates a facile strategy for designing anti-swelling underwater adhesives by leveraging the ambient solvent effect, which is expected to offer some insights for the development of next-generation adhesive soft materials tailored for aqueous environments.

Phase Behavior and Viscosity in Biomass Burning Organic Aerosol and Climatic Impacts.

Smoke particles generated by burning biomass consist mainly of organic aerosol termed biomass burning organic aerosol (BBOA). BBOA influences the climate by scattering and absorbing solar radiation or acting as nuclei for cloud formation. The viscosity and the phase behavior (i.e., the number and type of phases present in a particle) are properties of BBOA that are expected to impact several climate-relevant processes but remain highly uncertain. We studied the phase behavior of BBOA using fluorescence microscopy and showed that BBOA particles comprise two organic phases (a hydrophobic and a hydrophilic phase) across a wide range of atmospheric relative humidity (RH). We determined the viscosity of the two phases at room temperature using a photobleaching method and showed that the two phases possess different RH-dependent viscosities. The viscosity of the hydrophobic phase is largely independent of the RH from 0 to 95%. We use the Vogel-Fulcher-Tamman equation to extrapolate our results to colder and warmer temperatures, and based on the extrapolation, the hydrophobic phase is predicted to be glassy (viscosity >1012 Pa s) for temperatures less than 230 K and RHs below 95%, with possible implications for heterogeneous reaction kinetics and cloud formation in the atmosphere. Using a kinetic multilayer model (KM-GAP), we investigated the effect of two phases on the atmospheric lifetime of brown carbon within BBOA, which is a climate-warming agent. We showed that the presence of two phases can increase the lifetime of brown carbon in the planetary boundary layer and polar regions compared to previous modeling studies. Hence, the presence of two phases can lead to an increase in the predicted warming effect of BBOA on the climate.

Formulation and evaluation of a novel controlled release mefenamic acid pluronic lecithin organogel

Based on pluronic lecithin, PLO gels were established in the present research as a topical carrier for the regulated delivery of mefenamic acid. To explore various factors utilizing In vitro diffusion experiments and in vivo study, ten organized formulations have been created using such methods that used lecithin as a lipophilic phase as well as pluronic F-127 as a hydrophilic phase in variable proportions. The pH values of all formulations were found to be between 5.60 and 5.75, which is nonirritating, and to be off-white, homogeneous, and unwilling to wash off easily. In formulations F1 to F5 (lecithin) but also F6 to F10 (pluronic), an increase in polymer concentration led to a drop in gelation temperature, an increase in viscosity, as well as a reduction within the spreadability of gels with a tendency for polymers to form rigid 3D networks. Higher viscosity organogels have been proven to be more stable and delay drug release from the gel. The formulations of F2 and F3 have been chosen for kinetic tests and stability studies because they had the most significant percentage of drug content and the highest drug release during eight hours, and all physical parameters were found to be within acceptable limits. It was discovered that the order of drug release through different formulations was F1to F10. A drug is removed from the improved formulation F2 in a regulated manner according to zero-order rate kinetics. The optimized mefenamic acid organogel (F2) in vivo anti-inflammatory effectiveness against a commonly used commercial product (Volini gel) was determined to be satisfactory but also significant.

Using a Tunable Triblock Cationic Polymer to Unravel Performance and Durability Effects in Anion Exchange Membrane Based Electrolysis

The use of anion exchange membranes (AEMs) as the polymer electrolyte membrane and related cationic polymers as ionomers in the electrodes of water splitting electrolyzers could lead to significant advantages including the elimination of precious metal electrocatalysts. Because oxygenated radicals in base have a very much lower half life than in acid these materials can be based on hydrocarbon backbones. This leads to an enormous possible variation in polymer chemistry and, while exciting from the point of view of the creation of new polymer chemistries, has led to a lack of detail in determining exactly how all of these many polymers really behave in terms of performance and durability. All of the new materials that are currently being commercialized are designed to be free standing films that are chemically stable to attack by the strongly nucleophilic hydroxide anion. Often these polymers have excessive swelling and poor mechanical properties and lack easy variation enabling their modification to the properties required for an ionomer. Studies where the effect of film processing on performance or durability are also lacking. There is a chronic lack of knowledge in how cationic polymers interact with catalyst particles, charge carrier and the AEM in electrodes. Further complicating these studies is whether the device is operated in water, carbonate or hydroxide solution. The first of which give unexpectedly low performance but may be more amenable to long durability and latter of which gives high performance and low durability.We have developed a triblock co-polymer, with polychlorostyrene blocks that can be quaternized to give a hydrophilic phase and a central hydrophobic polyethylene (pE) block that gives the material good mechanical properties. This seemingly simple system can show tremendous variations. We can control the polymer block lengths and overall molecular weight of the polymer. The material can be suspension cast or melt processed to obtain uniform films. The films are post-quaternized and we can control the degree of functionalization and the nature of the cation. What is interesting about these materials is that for all anions that we have studied their conductivity behavior indicates that they are fully dissociated. We hypothesize that the pE content of the films localizes the water, this has the effect of both promoting anion conduction and also not wetting much of the polymer and so improving the durability and mechanical properties. In a series of films where we systematically increase the pE content, the materials swell less but do not necessarily loose performance. They do however show durability improvements, where a material that is 50% pE will thin in an electrolysis test giving rise to a degradation rate of -23 mV/h, a material with 80% pE will show a degradation rate of +400mV/h, at 500 μA/cm2. Further understanding of these materials is likely to result in further durability improvements. Performance and durability can also be varied by the method by which the film is processed.By using an unsaturated version of the cationic triblock co-polymer in electrode formulations and post hydrogenating we can insolubilize the polymer (by creating an insoluble pE containing polymer insitu) as the ionomer in the electrode. This allows us to study, ionomer loading and to begin to control the positioning of the ionomer. We have baselined these materials using Ni supports, and studied Membrane electrode assemblies on our optimized membranes. These ionomers are surprisingly durable as they contain aromatic groups, leading to further speculation that the localization of the water in the material again gives performance and durability advantages. In this talk we will also show how ionomer chemistry can be used to improve the performance and durability of electrolysis electrodes with either silver, cobalt oxide, or manganese oxide.

Liquid-Liquid Phase Separation in Single Suspended Aerosol Microdroplets.

Liquid-liquid phase separation (LLPS) is ubiquitous in ambient aerosols. This specific morphology exerts substantial impacts on the physicochemical properties and atmospheric processes of aerosols, particularly on the gas-particle mass transfer, the interfacial heterogeneous reaction, and the surface albedo. Although there are many studies on the LLPS of aerosols, a clear picture of LLPS in individual aerosols is scarce due to the experimental difficulties of trapping a single particle and mimicking the suspended state of real aerosols. Here, we investigate the phase separation in individual contactless microdroplets by a self-constructed laser tweezer/Raman spectroscopy system. The dynamic transformation of the morphology of optically trapped droplets over the course of humidity cycles is detected by the time-resolved cavity-enhanced Raman spectra. The impacts of pH and inorganic components on LLPS in aerosols are discussed. The results show that the increasing acidity can enhance the miscibility between the hydrophilic and hydrophobic phases and decrease the separation relative humidity of aerosols. Moreover, the inorganic components also have various impacts on the aerosol phase state, whose influence depends on their different salting-out capabilities. It brings possible implications on the morphology of actual atmospheric particles, particularly for those dominated by internal mixtures of inorganic and organic components.

Extended Q-range small-angle neutron scattering to understand the morphology of proton-exchange membranes: the case of the functionalized syndiotactic-polystyrene model system.

Semi-crystalline polymers exhibit microphase separation into crystalline and amorphous domains characterized by multiple structural levels with sizes ranging from ångströms to hundreds of nanometres. The combination of small-angle (SANS) and wide-angle (WANS) neutron scattering on the same beamline enables reliable insitu characterization of such materials under application-relevant conditions, with the unique advantage of contrast variation by controlled labelling, allowing the structure of such multi-component systems to be resolved in detail. This paper reports a structural analysis performed on deuterated polymer membranes based on syndiotactic polystyrene (sPS) using an extended Q-range SANS and WANS combination, always with the same neutron scattering instrument, either a pinhole SANS diffractometer installed at a research reactor or a 'small- and wide-angle' time-of-flight diffractometer installed at a neutron spallation source. sPS is a semi-crystalline material that becomes hydrophilic and proton conducting when suitable functionalization is achieved by thin film sulfonation, and can form various co-crystalline complexes (clathrates) with small organic molecules stored in the crystalline phase as guests in the vacancies between the polymer helices. Therefore, this material is interesting not only for its conducting properties but also for its versatility as a model system to evaluate the usefulness of extended Q-range neutron scattering in such studies. Variation of neutron contrast was achieved in the amorphous hydrophilic phase by using H2O or D2O to hydrate the membranes and in the crystalline phase by loading the clathrates with deuterated or protonated guest molecules. The experimental approach, the advantages and limitations of the two types of instrumentation used in such analyses, and the main results obtained with respect to the structural characterization of sulfonated sPS membranes under different hydration and temperature conditions are reported, and the potential of this method for similar structural studies on other semi-crystalline polymeric materials is discussed.

A biocompatible lipid-based bigel for topical applications

The development of biocompatible delivery systems is a necessity for medical and topical applications. Herein, the development of a new bigel for topical application is described. It is composed of 40% colloidal lipid hydrogel and 60% olive oil and beeswax oleogel. Its characterization and the potential of the bigel as a drug carrier through the skin was evaluated in vitro using fluorescence microscopy and two phases of the bigel were labeled with two fluorescent probes: sodium fluorescein (hydrophilic phase) and Nile red (lipophilic phase). The structure of the bigel showed two phases with fluorescence microscopy in which the hydrogel phase was incorporated into a continuous oleogel matrix. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) presented a combination of vibrations characteristic of the different molecules forming the bigel, and Differential Scanning Calorimetry (DSC) showed different transitions attributed to beeswax lipids. Small-angle and wide-angle X-ray scattering (SAXS and WAXS) indicated a predominant lamellar structure with orthorhombic lateral packing that could be related to the arrangement of beeswax crystals. Bigel enables deeper penetration of hydrophilic and lipophilic probes into deeper layers, making it a promising candidate for effective topical carriers in medical and dermatological applications.

Hydrogels of arrested phase separation simultaneously achieve high strength and low hysteresis.

Hydrogels are being developed to bear loads. Applications include artificial tendons and muscles, which require high strength to bear loads and low hysteresis to reduce energy loss. However, simultaneously achieving high strength and low hysteresis has been challenging. This challenge is met here by synthesizing hydrogels of arrested phase separation. Such a hydrogel has interpenetrating hydrophilic and hydrophobic networks, which separate into a water-rich phase and a water-poor phase. The two phases arrest at the microscale. The soft hydrophilic phase deconcentrates stress in the strong hydrophobic phase, leading to high strength. The two phases are elastic and adhere through topological entanglements, leading to low hysteresis. For example, a hydrogel of 76 weight % water, made of poly(ethyl acrylate) and poly(acrylic acid), achieves a tensile strength of 6.9 megapascals and a hysteresis of 16.6%. This combination of properties has not been realized among previously existing hydrogels.

Hydrophilic deep eutectic solvent based microextraction procedure for the determination of four paraben preservatives in vitamin D for babies: A green approach

In this study, an easily available, sensitive, and fast hydrophilic deep eutectic solvent-liquid phase microextraction method developed using deep eutectic solvent (DES) as a green solvent for the determination and microextraction of paraben (methyl, ethyl, propyl, and butyl) preservatives in vitamin D for babies. The highest yield for extraction recovery was obtained using DES consisting of a 1:4 M ratio of choline chloride and acetic acid. Moreover, various optimization parameters such as DES volume, DES type, sample volume, and centrifugation time were investigated in order to develop a real sample specific microextraction method. Relative standard deviation values were 0.92%-2.87%, the detection limit was 0.194–0.254 µg/mL, and extraction recovery values were between 87.40% and 102.98%. The method developed in this study was successfully applied to 5 different babies in vitamin D for babies obtained from pharmacies for the determination of methyl, ethyl, propyl, and butylparaben. As far as we know, it is the first study conducted both in terms of the determination of paraben preservatives in vitamin D for babies and in terms of the fact that DES used in this study is used for the first time in vitamin D for babies.

In situ assay of the reducing sugars in hydrophilic natural deep eutectic solvents by a modified DNS method

The DNS assay has been already a universally method for the in situ determination of reducing sugars (RS) in aqueous phase solvents. Today, “greener biorefineries” require in situ measurement of reducing sugars in non-aqueous solvents such as natural deep eutectic solvents (NADESs). Therefore, that DNS assay cannot be performed successfully in such eutectic phase solvent becomes a puzzle that must be solved. In this work, an improved DNS method, which we call the DNS'' method, was established and implemented successfully in hydrophilic eutectic phase solvent systems (hiNADES). The tickets to the success of DNS'' method are the inserted two essential steps, water-adding disintegration and pH alkalization. Then we tested two excellent RS solvents (ChCl_Gly and ChCl_LA) from six synthetic ChCl-based hiNADESs. The optimal disintegration conditions for assaying RS in ChCl_LA/NaOH (ChCl_Gly/H2O) were volume ratio 3: 1 (3: 1), molar concentration 2.0 mol/L (0 mol/L). Thereafter, we drew the standard curves of seven RSs in ChCl_Gly and ChCl_LA, which are glucose, xylose, fructose, mannose, fucose, rhamnose, and maltose. We determined that HMF interferes with DNS assay in hiNADES. The principles and standard procedures of DNS'' method were also investigated. Finally, the enzymatic saccharification of microcrystalline cellulose (MCC) by two commercial Trichoderma reesei cellulases (Celluclast® 1.5 L and Cellic® CTec2) in neat hiNADES was tracked using the DNS'' method.

COMPARISON OF THE PROPERTIES OF 3-AMINOPROPYL SILICA WITH DIFFERENT NITROGEN CONTENT IN HILIC MODE

A comparison of 4 amino phases representing 3-aminopropyl silica batches with different amount of grafted functional groups was made. To evaluate the chromatographic properties of the adsorbents, the Tanaka test for hydrophilic stationary phases was used, and the retention of polar substances of various classes in HILIC mode was also studied. It is shown that even small changes in nitrogen content between different batches of 3-aminopropyl silica have a significant effect on the retention of polar analytes. Hydrophilicity of a substrate was shown to have the greatest effect on its chromatographic behavior, and its evaluation using the Tanaka test is the basis for a batch selection either for separation of particular classes of polar substances or for further modification aiming at obtaining new phases.