Mixture Of Dimethylformamide Research Articles

Tunable diameter of electrospun fibers using empirical scaling laws of electrospinning parameters

This study introduces a new semi-empirical power-law model for predicting electrospun fiber diameter (D), addressing key processing parameters. Polycaprolactone (PCL) fibers were produced using a solvent mixture of Trichloromethane (TCM), Dimethyl Formamide (DMF), and ethanol (EtOH). Systematic experiments validated an existing theoretical model and led to the development of a novel model: D ∼ (c1/2η1/3Q1/5X2/3)/(U2/3ω1/4I1/5). This model incorporates seven crucial parameters: viscosity (η), concentration (c), voltage (U), spinning distance (X), flow–rate (Q), current (I) and collector wheel rotation speed (ω). The model was validated through a partial factorial design experiment, proving to be a valuable and reliable tool for predicting fiber diameters and optimizing electrospinning processes. The ability to control fiber diameter is essential for tailoring electrospun fibers for various applications, including biomedicine, filtration, sensors, and lightweight materials.

Enantioselective Transfer Hydrogenation of α-Methoxyimino-β-keto Esters.

α-Methoxyimino-β-keto esters are reported to undergo highly enantioselective catalytic transfer hydrogenation using the Noyori-Ikariya complex RuCl(p-cymene)[(S,S)-Ts-DPEN] in a mixture of formic acid-triethylamine and dimethylformamide at 25 °C. The experimental study performed on over 25 substrates combined with computational analysis revealed that a Z-configured methoxyimino group positioned alpha to a ketone carbonyl leads to higher reactivity and mostly excellent enantioselectivity within this substrate class. Density functional theory calculations of competing transition states were used in rationalizing the origins of enantioselectivity and the possible role of the methoxyimino group in the reaction outcome.

Strong impact of exposure to water/solvent mixtures on permeance of nanofiltration membranes

Water/solvent mixtures released from industrial processes, especially in pharma and fine chemical synthesis or in advanced oil production, are an environmental concern, necessitating the development of efficient remediation and recycling techniques. Solvent-tolerant nanofiltration (STNF), situated between aqueous nanofiltration (NF) and solvent-resistant nanofiltration (SRNF), offers a promising solution. This study investigates the potential of using aqueous NF- and SRNF-membranes to treat water/solvent mixtures. Commercial membranes (NF270, DuraMem® 300, DuraMem® 200) and a lab-synthesized polyvinylidene fluoride (XL-PVDF NF) membrane were used to treat dimethyl sulfoxide (DMSO), acetonitrile (ACN), Isopropyl alcohol (IPA), or dimethylformamide (DMF) mixtures with water. The addition of 10% DMSO, ACN, IPA, or DMF to water significantly reduced the permeance of these NF-membranes, and an increase in temperature failed to restore the initial permeance. Changes in both viscosity and surface tension of the water/solvent solutions strongly influence the permeance of the NF-membranes. Flory-Huggins and Zimm-Lundberg theories offered an explanation for the phenomenon where solvent clusters form within the dense polymer matrix of NF-membranes upon exposure to water/solvent mixtures, resulting in decreased water permeabilities. NMR analysis identified of the presence of small amounts of solvents in the STNF-membranes, even still after prolonged exposure to pure water permeation. The results emphasize the current shortcomings of aqueous and solvent-resistant membrane chemistries in handling water/solvent mixtures. Minor solvent additions significantly modify NF membrane permeance, emphasizing the need for innovative material design, especially given the variable solvent content in industrial applications.

A Disposable Sensor for Rapid Histamine Detection in Fish Using Molecularly Imprinted Carbon Paste Electrode

Introduction: Histamine (HM), a toxic compound, is produced due to an enzymatic reaction when histidine (HS)-rich red fish such as tunas and other fish and their processed products are improperly stored, e.g., leaving them at room temperature. With the increasing popularity of raw fish consumption, HM analysis is mandatory for these fish in various countries. However, the conventional immunoassay method is time-consuming, costly, and technically demanding, burdening wholesalers heavily.Molecularly Imprinted Polymers-based materials are attractive materials for sensor fabrication due to their high selectivity, stability, and ease of production. In this study, we attempted to develop a Molecularly Imprinted Polymer grafted Carbon Paste (MIP-CP) for histamine sensing. Experimental Methods First, a radical polymerization initiator was fixed on the surface of graphite particles [1]. Next, histamine dihydrochloride, itaconic acid, and ethylene glycol dimethacrylate (EDMA) were dissolved in a mixture of distilled water and dimethylformamide to prepare a polymerization solution. The polymerization solution and initiator-fixed graphite were placed in a quartz tube and irradiated with a xenon lamp for 1 hr. HM was extracted and removed using acetic acid. MIP-CP was prepared by mixing MIP-grafted graphite and silicon oil containing ferrocene in a 7:3 weight ratio. Non-imprinted polymer (NIP)-CP was also prepared using the same procedure, except that HM was not added.Differential pulse voltammetry (DPV) was performed with electrodes packed with the obtained MIP-CPs on a disposable chip [2]. The performance of the HM sensor was evaluated based on the relationship between the oxidation current of ferrocene and HM concentration. (Measurement range 0 μg/mL~100 μg/mL) Experimental results The dependence of the oxidation current density on HM concentration at the NIP and MIP electrodes was confirmed (0.0085 μA-mL/μg, R²=0.9357). The increase in current density with increasing HM concentration at the MIP-CP electrode was more than three times greater than at the NIP-CP electrode. This confirmed that MIP-CP exhibited current changes corresponding to the interaction between HM and HM-imprinted sites. Furthermore, the current increased linearly with increasing HM concentration from 0-100 µg/mL. This dynamic range includes 50 µg/mL, which is considered the lower limit of acceptable Hm concentration in fish meat.However, the current value was constant for HS concentration at 0.75 µA over the range of 40-100 µg/mL and below. Therefore, the sensor is saturated with HS at concentrations above 40 µg/mL, and histidine interference can be excluded by subtracting 0.75 µA from the current value obtained when measuring the fish meat sample. Conclusion We successfully developed a reagentless, disposable histamine sensor using MIP-CP, which provides a rapid, reliable, and cost-effective method for histamine detection in fish.

Supercritical Antisolvent Precipitation of Levofloxacin Hydrochloride from a Single-Phase and a Two-Phase CO2–Dimethylformamide Mixture

Supercritical Antisolvent Precipitation of Levofloxacin Hydrochloride from a Single-Phase and a Two-Phase CO2–Dimethylformamide Mixture

Tunable Optical Properties and the Role of Defects on the Carrier Lifetimes of Cs3Sb2I9 Synthesized in Various Solvents

Pb‐free halide perovskites have recently attracted immense attention due to the number of advantages in their optical and electronic properties. However, tuning the optical bandgap with minimized amounts of point defects is a particularly challenging task in photovoltaics. It is pivotal to clearly understand the detailed relationship between the bandgap change with defect generation and charge carrier lifetime. In this study, Cs3Sb2I9 crystals are synthesized by varied choice of solvents, namely, γ‐butyrolactone, a mixture of dimethylformamide and dimethyl sulfoxide, and hydroiodic acid. Although the same principles of decreasing solubility and crystallization are applied, Cs3Sb2I9 crystals with different size and shape in microscopic and macroscopic scale are obtained during heating and cooling of the solution. The synthesized crystals are investigated using a combination of different spectroscopies including Raman, UV–visible, and time‐resolved photoluminescence. In the results, it is suggested that there is a strong relationship between Urbach energy and the lifetime of charge carriers. In this research, readily applicable practical principles and examples of how to control the defects for the advancement in Pb‐free perovskite photovoltaics are provided.

Radiosensitizer-Releasing Fiducial ‘Nanofiducial’: A New Concept in Radiotherapy

Fiducial is a material used in stereotactic radiotherapy (SRT). Additionally, radiosensitizing nanostructures are an interesting opportunity for improving RT clinical benefits. In this study, it was aimed to combine both technologies by designing and synthesizing a tailor-made 'nanofiducial' functionalized with a radiosensitizing nanoparticle. AGuIX are sub-5 nm nanoparticles containing gadolinium (Z = 64) having both MRI contrast capability and radiosensitization effects. It was planned to embed the AGuIX nanoparticle in poly(lactic-co-glycolic acid) (PLGA) nanofiber mats. Nanofiber mats were prepared by electrospinning method. Imaging of the nanofiber structure was evaluated using Scanning Electron Microscopy (SEM). Detailed analyzes were carried out for porosity and mechanical strength measurements in addition to DSC and FTIR. EDS micrographs of fiber meshes were taken to show that AGuIX was loaded into nanofiber mats. The amount of AGuIX released from the nanofiber mats in PBS was quantified by inductively coupled plasma mass spectrometry (ICP-MS). Nanofibers were produced in two different forms, one 'no AguIX' embedded and the other loaded with '5 % AguIX'. The nanofiber formulation was prepared using PLGA poly(lactic-co-glycolic acid) 50:50 polymer with a molecular weight of 38,000-54,000. A mixture of Tethrahydrofuran and Dimethylformamide was used as the polymer solvent. The mixing ratio of THF:DMF was 65:35 and the rate of PLGA was 25%. According to the SEM results, nanofibers were randomly aligned and the release of AGuIX was observed up to 12 hours after fiducial formation in pH 7.4 PBS buffer solution. Nanofiducials computed tomography images were taken and nanofiducials were viewed as hypointense area. Hounsfield Unit values for "no AGuIX" sample and "5% AGuIX containing sample" were as follows: average -62.5(max -16; STD 11.7); -87.2 (max -60; STD 8.7). Radiosensitizing nanostructures are promising for increasing the effectiveness of radiotherapy in cancer treatment, achieving high dose effects at lower doses, and reducing side effects. In this study, a fiducial structure functionalized with an effective radiosensitizing nanoparticle was preliminary tested for local application.

Symmetry-breaking charge transfer in an excited acridine-dione derivative: Effects of hydrogen bonding, clustering, and cooperativity in mixtures of methanol and dimethylformamide

A theory of fluorescence quenching of photoexcited centrosymmetric acridine-dione derivative induced by H-bonding interactions with solvent in mixtures of methanol (MeOH) and N,N-dimethylformamide (DMF) is developed. The theory takes into account both dynamic and static mechanisms of the quenching. An unusual threshold-type dependence of the quenching efficiency on the concentration of methanol in the mixture observed earlier in experiment is analyzed theoretically under the following assumptions: (i) individual MeOH molecules and their short hydrogen-bonded clusters form weak complexes with the dye in solution and these interactions do not affect fluorescence kinetics significantly, (ii) long clusters form strongly bound complexes with the dye and thus induce symmetry-breaking intramolecular charge transfer and efficient quenching of fluorescence. These assumptions are consistent with the cooperative character of H-bonding in alcohols and allow one to explain the observed absence of quenching at MeOH concentrations below ∼9 M. A model of H-bond clustering in mixtures of alcohols and H-bond-accepting solvents is developed. The suggested approach gives a quantitative description of the observed concentration dependence of the fluorescence yield and well reproduces the non-exponential kinetics of the fluorescence decay measured in experiments. Since the degree of the charge transfer dissymmetry in these processes is sensitive to interactions between the dye and solvent, new possibilities emerge for experimental studies on details of H-bond clustering in protic solvents.

Thermo‐Responsive Ultrafiltration Block Copolymer Membranes Based on Polystyrene‐block‐poly(diethyl acrylamide)

AbstractWithin the present work, a thermo‐responsive ultrafiltration membrane is manufactured based on a polystyrene‐block‐poly(diethyl acrylamide) block copolymer (BCP). The poly(diethyl acrylamide) block segment features a lower critical solution temperature (LCST) in water, similar to the well‐known poly(N‐isopropylacrylamide), but having increased biocompatibility and without exhibiting a hysteresis of the thermally induced switching behavior. The BCP is synthesized via sequential “living” anionic polymerization protocols and analyzed by 1H‐NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. The resulting morphology in the bulk state is investigated by transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) revealing the intended hexagonal cylindrical morphology. The BCPs form micelles in a binary mixture of tetrahydrofuran and dimethylformamide, where BCP composition and solvent affinities are discussed in light of the expected structure of these micelles and the resulting BCP membrane formation. The membranes are manufactured using the non‐solvent induced phase separation (NIPS) process and are characterized via scanning electron microscopy (SEM) and water permeation measurements. The latter are carried out at room temperature and at 50 °C revealing up to a 23‐fold increase of the permeance, when crossing the LCST of the poly(diethyl acrylamide) block segment in water.

Development of an Inline Tube-in-Tube Solvent Exchanger for Continuous-Flow Swap from High- to Low-Boiling Solvent

Solvent swap from high- to low-boiling solvents still presents a huge challenge in the development of multistep continuous-flow processing. Herein, a miniaturized inline tube-in-tube solvent exchanger combining intensified convective mass transfer with droplet evaporation is presented. The design involves intimate contact between droplet and gas phases in countercurrent mode within a mesofluidic tube. Its solvent removal performance was evaluated by using pure solvents and binary mixtures. The results revealed that the commonly used solvents with low to medium boiling points (Tb < 100 °C) can be completely evaporated at room temperature without the need of heating. Significantly, high-boiling solvents can be efficiently removed at temperatures much lower than their boiling points. Its capacity for the separation of binary mixtures was corroborated by removing dichloromethane from a 50:50 mol % dichloromethane–dimethylformamide mixture and acetic acid from a 50:50 mol % p-nitroacetophenone–acetic acid mixture. A computational fluid dynamics (CFD) model based on the phase field approach was developed to quantitatively describe the droplet evaporation process, providing indepth evaporation dynamics and furthering our understanding on the concomitant phase change phenomenon. The comparison with other types of evaporators highlights its superior evaporative performance. To enable fast design and optimization of this type of evaporators, a correlation model was proposed to calculate the evaporation rate with good prediction performance. The usefulness of this device was demonstrated by performing a two-step continuous-flow synthesis of 4-aminoacetophenone. The combined experimental and CFD studies demonstrate that this tube-in-tube device can serve as a convenient and efficient tool for continuous solvent exchange, particularly from high- to low-boiling solvents, in continuous-flow synthesis.

Partial Replacement of Dimethylformamide with Less Toxic Solvents in the Fabrication Process of Mixed-Halide Perovskite Films

The technology of perovskite solar cells (PSC) is getting close to breaching the consumer market. Yet, one of the current challenges is to reduce the toxicity during their fabrication by reducing the use of the toxic solvents involved in the perovskite fabrication process. A good solubilization of lead halides used in hybrid perovskite preparation is required, and it is only possible with polar solvents. A mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is the most popular solvent combination for a perovskite precursor solution. DMF is necessary to ensure a good dissolution of lead iodide, but it is also the most toxic solvent. In this paper, we study the replacement of the dimethylformamide with presumably less toxic alternatives, such as N-methyl-2-Pyrrolidone (NMP) and ethyl acetate (EA), for the preparation of the K0.1FA0.7MA0.2PbI2.8Cl0.2 (KFAMA) hybrid perovskite. The perovskite thin films were investigated by various characterization techniques: X-ray diffraction, atomic force microscopy, scanning electron microscopy, and UV–vis spectroscopy, while the photovoltaic parameters were determined by measuring the IV curves of the corresponding solar cells. The present study shows that by keeping the same deposition parameters as when only DMF solvent is used, the partial solvent substitution with NMP and EA gives promising results for reducing the toxicity of the fabrication process of KFAMA-based PSCs. Thus, with no specific optimization of the deposition process, and for the maximum possible partial substitution of DMF with NMP and EA solvents, the loss in the power conversion efficiency (PCE) value is only 35% and 18%, respectively, associated with the more structural defects promoted by NMP and EA.

Synthesis of a graft copolymer of chloroprene rubber with acrylic acid as a shoe adhesive

Synthesized graft copolymers of chloroprene rubber with acrylic acid. A mixture of benzene and dimethylformamide was used as a solvent, and potassium persulfate was used as a polymerization initiator. Based on the dependence of the copolymerization rate on the concentrations of components and temperature, the order of the reaction rate in terms of the concentration of acrylic acid (2.0), potassium persulfate (1.2) and the activation energy of the process (24.4 kJ/mole) were determined. The degree of grafting of polyacrylic acid increases from 2% to 140% with increasing process time, monomer and initiator concentrations. Grafting efficiency is high (70-90%) in a wide range of time and component concentrations. The graft copolymer has high adhesion to the surface of the skin and tissue.

Spraying Fluorinated Silicon Oxide Nanoparticles on CuONPs@CF-PVDF Membrane: A Simple Method to Achieve Superhydrophobic Surfaces and High Flux in Direct Contact Membrane Distillation.

Desalinization of seawater can be achieved by membrane distillation techniques (MD). In MD, the membranes should be resistant to fouling, robust for extended operating time, and preferably provide a superhydrophobic surface. In this work, we report the preparation and characterization of a robust and superhydrophobic polyvinylidene fluoride membrane containing fluoroalkyl-capped CuONPs (CuONPs@CF) in the inner and fluorinated capped silicon oxide nanoparticles (SiO2NPs@CF) on its surface. SiO2NPs@CF with a mean diameter of 225 ± 20 nm were prepared by the sol method using 1H,1H,2H,2H-perfluorodecyltriethoxysilane as a capping agent. Surface modification of the membrane was carried out by spraying SiO2NPs@CF (5% wt.) dispersed in a mixture of dimethyl formamide (DMF) and ethanol (EtOH) at different DMF/EtOH % v/v ratios (0, 5, 10, 20, and 50). While ethanol dispersed the nanoparticles in the spraying solution, DMF dissolved the PVDF on the surface and retained the sprayed nanoparticles. According to SEM micrographs and water contact angle measurements, the best results were achieved by depositing the nanoparticles at 10% v/v of DMF/EtOH. Under these conditions, a SiO2NPs covered surface was observed with a water contact angle of 168.5°. The water contact angle was retained after the sonication of the membrane, indicating that the modification was successfully achieved. The membrane with SiO2NPs@CF showed a flux of 14.3 kg(m2·h)-1, 3.4 times higher than the unmodified version. The method presented herein avoids the complicated modification procedure offered by chemical step modification and, due to its simplicity, could be scalable to a commercial membrane.

Amino-Acid-Functionalized Metal–Organic Frameworks as Excellent Precursors toward Bifunctional Metal-Free Electrocatalysts

Metal–organic frameworks (MOFs) are promising precursors for synthesizing functional carbon materials, and their atomic-scale designs have recently been studied for improving their performance. Herein, we synthesized an alanine-decorated MOF-5 via a solvothermal method using a mixture of dimethylformamide and water as the solvent. Experimental and computational investigations revealed that alanine residues were located in the micropores of MOF-5 due to interactions between the MOF Zn clusters and the carboxylic acid groups of the alanine moieties. In addition, the alanine-decorated MOF-5 was carbonized at 1100 °C for application as an electrocatalyst. It was found that the resulting N-doped carbonized sample exhibited excellent catalytic activities in the oxygen reduction and hydrogen evolution reactions and afforded superior results to those reported for other metal-free carbon catalysts. This high activity originated from the single nitrogen configuration (pyrrolic N) in the hierarchical pores. This article presents a facile strategy for the syntheses of both functionalized MOFs and N-doped carbon materials.

Polyester-releasing sesamin by electrospinning technique for the application of bone tissue engineering

ABSTRACT Sesamin, a significant lignin compound isolated from sesame (Sesamum indicum Linn), is well known for its antioxidant, anti-inflammatory, and tissue growth promotion properties. Bioabsorbable poly(ε-caprolactone) (PCL) is also a well-known polymer applied to various fields of medicine as biomaterials. The main objective of this research was to produce a prototype material from PCL and sesamin by electrospinning technique for bone tissue engineering applications. Dichloromethane and dimethylformamide (7:3) mixture was used as the solvent system for fabrication of PCL nanofiber with different loads of sesamin concentrations (1–6 wt%). The crystallinity levels decreasing and the entrapment efficiency increasing (86.87%–93.97%) were observed while sesamin concentrations were increased. The infrared spectra of electrospun mats confirmed that sesamin corporated into fibrous networks. The sesamin-loaded PCL nanofibrous membranes showed a significant release of sesamin in the range of 1.28–8.16 μg/mL within 10 weeks. The release data were fitted to zero order, first order, Higuchi and Korsmeyer-Peppas models to evaluate sesamin-releasing mechanisms and kinetics. The releasing kinetics of sesamin followed the Fickian diffusion mechanism of Korsmeyer-Peppas (R2 = 0.99). In vitro experiments with an osteosarcoma cell line (MG-63) revealed cell attachment, biocompatibility, and promotion of bone marker expression, the alkaline phosphatase (ALP) activity were studied. The electrospun PCL nanofiber loaded with sesamin had the potential as a scaffold for sesamin delivery to bone cells and applications in biomedicine.

Performance study of novel PES membrane using electrospray deposition method for organic contaminants separation

The aim of this study is to design and fabricate a new kind of membrane that could be used effectively in wastewater treatment. In this study, a novel type of electrosprayed thin membrane was synthesized via electrospray deposition technique and its properties were compared with electrospun membrane in terms of structure and separation efficiency. The electrosprayed thin membrane was developed using dope solution composed of 20 wt. % polyethersulfone (PES) and 80 wt. % n-methyle-2-pyrrolidone/dimethylformamide mixture. The electrosprayed PES membrane exhibited water flux of up to 100 Lm−2h−1 at 2 bar with porosity of 76 % which is very similar to the electrospun membranes. The electrosprayed PES membrane also showed an excellent tensile strength up to 4.5 MPa and demonstrated about 81 % and 63 % rejection rate against humic acid (HA) and bovine serum albumin (BSA), respectively when tested at 2 bar. The fouling of the membrane was further studied using FTIR, TGA and XPS analysis and the results confirmed that the membrane did not suffer from substantial fouling. Moreover, a high flux recovery was recorded, indicating low fouling tendency of the membrane. Overall, the findings showed that the electrosprayed thin PES membrane performed better than the electrospun PES membrane for wastewater treatment.

Molecular characteristics, mechanism of synthesis, adhesive properties of graft copolymer of chloroprene rubber with acrylic acid

AbstractSynthesized graft copolymers of chloroprene rubber with acrylic acid in a solution of a mixture of dimethylformamide and benzene, in the presence of potassium persulfate. The gravimetric method determined the orders of the reaction rate by the concentrations of acrylic acid (2.0) and potassium persulfate (1.2), the total activation energy of the process (24.4 kJ/mol). It was found that the degree of grafting increases up to 140% with an increase in the concentration of the monomer, initiator, temperature, and process time. The efficiency of grafting changes insignificantly with changes in synthesis conditions and has a high value (67%–91%) over a wide range of concentrations, temperatures, and times. With an increase in the concentration of acrylic acid and a process time of up to 8 h, the molecular weight of the grafted polyacrylic acid chains increases to 38,000. IR Fourier,1H, and13C NMR spectroscopic studies established the mechanism of graft copolymerization. Radical active centers are formed as a result of hydrogen abstraction from the rubber molecule after interaction with potassium persulfate. Copolymers synthesized at a mass ratio of rubber:acrylic acid from 1:0.5 to 1:2, have excellent adhesion to the surface of the skin and textile material.

A Novel Method for the Preparation of Poly (Acrylamide-co-Acrylonitrile) Upper Critical Solution Temperature Thermosensitive Hydrogel by the Partial Dehydration of Acrylamide Grafted Polypropylene Sheets.

In an attempt to find a potential application of cell culture harvesting, a novel method for the preparation of an upper critical solution temperature (UCST) thermosensitive hydrogel was studied. An electron accelerator was used as the electron beam (EB) radiation source, and acrylamide (AAm) was first grafted onto the pre-irradiated polypropylene (PP) sheet. Then, the grafting layer of poly (acrylamide-co-acrylonitrile) (P (AAm-co-AN)) was obtained by the partial dehydration of the acylamino group into the cyano group in the solution mixture of sulfoxide chloride (SOCl2) and dimethyl formamide (DMF). The effects of the absorbed dose, AAm concentration, reaction time, and temperature on the degree of grafting were studied, respectively. The effect of the SOCl2 concentration on the conversion degree of the cyano group from the acylamino group was studied, followed by the temperature of the UCST. The UCST properties of the grafted samples with P (AAm-co-AN) were studied by quartz crystal microbalance (QCM) and atomic force microscope (AFM), respectively. The cytotoxicities of the hydrogels against cells were verified by CCK-8 studies.

Organic solvent vapor/thermal responsive binary gels with tunable transparency and mechanical strength

In this work, we illustrate the fabrication of binary gels via self-sorting assembly between β-cyclodextrin and the second gelators, which show significant transparency changes responsive to the solvent vapor and temperature. The mixing of β-cyclodextrin and clay minerals in the mixture of dimethylformamide and water produced opaque gels. After exposed to specific solvent environments, the light transmittance of opaque gels was greatly enhanced ascribed to the host-guest complexation between β-cyclodextrin and organic solvent vapors. Toluene, xylene, tetrahydrofuran, dioxane and pyridine aroused gel fiber to bulky crystal transformation, which also slightly enhanced the mechanical strength of the binary gels. In addition, the gelator could be expanded to organic gelator like folic acid. This work offers a feasible way to fabricate soft gel composites that show transparency changes responsive to solvent vapors.

Peculiar encounter between self-propelled droplet and static droplet: swallow, rerouting, and recoil

Understanding the outcome and mechanism of droplet–droplet collision is important in digital microfluidics, especially for the encounter between the self-propelled and static droplets. Observation of the collision process between a self-propelled droplet and another static liquid droplet on a poly(methyl methacrylate) substrate. The former is a mixture of dimethylformamide and 10 wt% Silwet L-77, while the latter can be either miscible or immiscible with the former. Four types of interesting outcomes after the encounter are identified: (i) swallow-and-run (liquid paraffin), (ii) swallow-run-pinning (olive oil), (iii) rerouting-and-run (water), and (iv) recoil-and-run (glycerol). The swallow behavior is observed as the two droplets are immiscible, but the rebound behavior is acquired as they are miscible. The former can be explained by the two spreading coefficients, while the latter may be attributed to the buildup of the gradient of the interfacial tension upon contact.