Synthesis Of Functional Materials Research Articles

Structure‐Prediction‐Oriented Synthesis of Thiophosphates as Promising Infrared Nonlinear Optical Materials

Oriented synthesis of functional materials is a focus of attention in material science. As one of the most important function materials, infrared nonlinear optical materials with large second harmonic generation effects and broad optical bandgap are in urgent need. In this work, directed by the theoretical structure prediction, the first series of non‐centrosymmetric (NCS) alkali‐alkaline earth metal [PS4]‐based thiophosphates LiCaPS4 (Ama2), NaCaPS4 (P21), KCaPS4 (Pna21), RbCaPS4 (Pna21), CsCaPS4 (Pna21) were successfully synthesized. Comprehensive characterizations reveal that ACaPS4 could be regarded as promising IR NLO materials, exhibiting wide bandgap (3.77‐3.86 eV), moderate birefringence (0.027‐0.064 at 1064 nm), high laser‐induced damage threshold (LIDT, ~10 × AGS), and suitable phase‐matching second harmonic generation responses (0.4‐0.6 × AGS). Structure‐properties analyses illustrate that the Ca‐S bonds show non‐ignorable covalent feature, and [PS4] together with [CaSn] units play dominant roles to determine the bandgap and SHG response. This work indicates that Li‐, Na‐ and K‐ analogs may be promising infrared nonlinear optical material candidates, and this is the first successful case of “prediction to synthesis” involving infrared (IR) nonlinear optical (NLO) crystals in the thiophosphate system and may provide a new avenue to the design and oriented synthesis of high‐performance function materials in the future.

Structure-Prediction-Oriented Synthesis of Thiophosphates as Promising Infrared Nonlinear Optical Materials.

Oriented synthesis of functional materials is a focus of attention in material science. As one of the most important function materials, infrared nonlinear optical materials with large second harmonic generation effects and broad optical bandgap are in urgent need. In this work, directed by the theoretical structure prediction, the first series of non-centrosymmetric (NCS) alkali-alkaline earth metal [PS4]-based thiophosphates LiCaPS4 (Ama2), NaCaPS4 (P21), KCaPS4 (Pna21), RbCaPS4 (Pna21), CsCaPS4 (Pna21) were successfully synthesized. Comprehensive characterizations reveal that ACaPS4 could be regarded as promising IR NLO materials, exhibiting wide bandgap (3.77-3.86 eV), moderate birefringence (0.027-0.064 at 1064 nm), high laser-induced damage threshold (LIDT, ~10 × AGS), and suitable phase-matching second harmonic generation responses (0.4-0.6 × AGS). Structure-properties analyses illustrate that the Ca-S bonds show non-ignorable covalent feature, and [PS4] together with [CaSn] units play dominant roles to determine the bandgap and SHG response. This work indicates that Li-, Na- and K- analogs may be promising infrared nonlinear optical material candidates, and this is the first successful case of "prediction to synthesis" involving infrared (IR) nonlinear optical (NLO) crystals in the thiophosphate system and may provide a new avenue to the design and oriented synthesis of high-performance function materials in the future.

Effect of fluid properties on intensification of heat transfer process in oil-water droplet flow in a T-shaped microchannel

Droplet-based microfluidics refers to the production and utilization of micrometer-sized droplets. This technology has found widespread applications in drug delivery, biotechnology, disease prevention, chemical analysis, cell research, and functional material synthesis. Cooling of high heat flux electronic systems and hot spots is another application of the droplet flow which is focused by the current work. In this paper, formation and hydrothermal performance of oil droplets in water flow in a T-junction microchannel is studied by a 3D numerical simulation. Effects of different parameters such as surface tension, wettability and heat flux on the droplet size, heat transfer rate and pressure drop are investigated. It is observed that the shear between the discrete and continuous phases results in recirculating zones in both phases which contribute to improved mixing and heat transfer rates. Liquid film thickness adjacent to the heated surface and the droplet velocity are two other factors that positively affect the heat transfer. Decreasing the surface tension is shown to enhance the heat transfer rate. Moreover, an optimum value is found for the contact angle as 135° at which a 23 % heat transfer enhancement is achieved. Results also indicate that droplet size decreases with increase of contact angle while it slightly increases with increase of the surface tension and negligibly varies with the applied heat flux.

Liquid Metal-Polymer Conductor-Based Conformal Cyborg Devices.

Gallium-based liquid metal (LM) exhibits exceptional properties such as high conductivity and biocompatibility, rendering it highly valuable for the development of conformal bioelectronics. When combined with polymers, liquid metal-polymer conductors (MPC) offer a versatile platform for fabricating conformal cyborg devices, enabling functions such as sensing, restoration, and augmentation within the human body. This review focuses on the synthesis, fabrication, and application of MPC-based cyborg devices. The synthesis of functional materials based on LM and the fabrication techniques for MPC-based devices are elucidated. The review provides a comprehensive overview of MPC-based cyborg devices, encompassing their applications in sensing diverse signals, therapeutic interventions, and augmentation. The objective of this review is to serve as a valuable resource that bridges the gap between the fabrication of MPC-based conformal devices and their potential biomedical applications.

Deep eutectic solvents as an emerging green platform for the synthesis of functional materials

Deep eutectic solvents (DESs) enable many processes to be environmentally friendly. This Tutorial Review aims to showcase the roles of DESs in the synthesis of functional materials from a green chemistry perspective.

Morphological Control of Functional TiO2 Films on Magnetic Nanoparticle’s Surface by Utilizing the Boric Acid-Containing Solutions

In recent years, various functional materials are used for electronic devices such as the smartphones and conductive materials. For the further expansion of these material’s usability and usage range, it is important to achieve the highly functionalized material’s manufacturing processes compatible with “green” processes. From this point of view, the development of a sustainable functional material synthesis method that achieves both high performance and reduced the environmental load has been required.As one of such functional materials, Kishimoto1)et al. reported the synthesis and application of colored magnetic toners powders by using the buffer solution of pH 7-12 as a reaction field. In their methods, metallic iron particles coated with a homogeneous nanometer ranged TiO2 films are synthesized, and their color can be freely controlled by controlling the thickness of their films because of the interference effect.However, it is also known that not only the homogeneous core-shell materials but also the plate-like or island-like structures can be sometimes formed on the core surface. Needless to say, contamination of these lowering the property of the functional materials. Conversely, if we can elucidate the formation mechanism of these films and can achieve the selectively formation of various structured films, new functional materials can be synthesized.Therefore, in this study, TiO2 film-coated particles with various morphologies such as plate-like and dot island-like films are tried to synthesized, through the elucidation of the interaction between the surface condition and reaction solution.Carbonyl iron powder (BASF EM grade, median diameter: 4-5 μm), and Clark& Lubs buffer solution (H3BO3-KCl-NaOHaq, pH 9, 0.4 M) were used. Tetra-isopropoxy titanium (C14H28O4Ti), hydrogen peroxide water, and ammonia water were used as the titanium oxide film raw materials in the subsequent film coating step. The temperature was optimized and film coating was performed so that the peroxotitanium bonds to the substrate surface.Boric acid buffer solution after suspended the carbonyl iron particles were analyzed by XPS (XPS K-Alpha, Thermo Fisher Scientific, USA), and it showed a tendency to be significantly oxidized as compared to the particles before suspension. Waveform separation of the XPS spectrum of the O1s peak indicated that these peaks consisted by the oxygen atoms in the OH- and Fe2O3 species. ESI-TOF-MS (Bruker Dltonics; microTOFII) analysis results of the solution obtained after contacting the buffer solution and metallic iron particles shows that borate ions tended to decrease after the reaction. Thus, by controlling the relationship between the iron surface, boric acid, and the buffer solution in the solution, surface oxidation condition of the iron substance particles affected the formation of the subsequent TiO2 coating reaction. Details of other results will be present in our presentation.1) WO/2003/031683, POWDER COATED WITH TITANIA FILM AND METHOD FOR PRODUCTION THEREOF.2）G. Bhargava et.al, Characterization of the “native”surface thin film on pure polycrystalline iron: A high resolution XPS and TEM study,” Applied Surface Science2007; 253, 4322-4329.

Full-components utilization: Study on simultaneous preparation of sodalite and separation of yttrium from coal gangue by chlorination roasting process

Kaolinite-type coal gangue is a solid waste from coal mining that contains valuable rare earth elements (REE) and kaolinite. The simultaneous recovery of REE and synthesis of functional materials utilizing kaolinite from coal gangue presents an opportunity for full utilization. This study introduces synchronous chlorination volatilization of REE and preparation of sodalite from coal gangue. Thermodynamic analysis revealed xenotime reacts directly with NaCl to produce YCl3 for volatilization with the presence of O2. The effects of various factors on yttrium recovery and sodalite synthesis, including temperature, time, additives, and NaCl dosage, were investigated. Optimal conditions were identified as roasting coal gangue with 13.3 wt% NaCl and 41.7 wt% Na2CO3 at 1000 ℃, resulting in 93.4% yttrium volatilization and a 100% conversion efficiency of sodalite. The addition of Na2CO3 was found to accelerate the transition from aluminosilicate minerals to sodalite, thus achieving an outstanding sodalite conversion efficiency. This approach offers a theoretical and practical foundation for the efficient utilization of solid waste.

Flexible Block Copolymer Metamaterials Featuring Hollow Ordered Nanonetworks with Ultra-High Porosity and Surface-To-Volume Ratio.

By utilizing bicontinuous and nanoporous ordered nanonetworks, such as double gyroid (DG) and double diamond (DD), metamaterials with exceptional optical and mechanical properties can be fabricated through the templating synthesis of functional materials. However, the volume fraction range of DG in block copolymers is significantly narrow, making it unable to vary its porosity and surface-to-volume ratio. Here, the theoretically limited structural volume of the DG phase in coil-coil copolymers is overcome by enlarging the conformational asymmetry through the association of mesogens, providing fast access to achieving flexible structured materials of ultra-high porosities. The new materials design, dual-extractable nanocomposite, is created by incorporating a photodegradable block with a solvent-extractable mesogen (m) into an accepting block, resulting in a new hollow gyroid (HG) with the largely increased surface-to-volume ratio and porosity of 77 vol%. The lightweight HG exhibits a low refractive index of 1.11 and a very high specific reduced modulus, almost two times that of the typical negative gyroid (porosity≈53%) and three times that of the positive gyroid (porosity≈24%). This novel concept can significantly extend the DG phase window of block copolymers and the corresponding surface-to-volume ratio, being applicable for nanotemplate-synthesized nanomaterials with a great gain of mechanical, catalytic, and optoelectronic properties.

Nitrogen-doped porous carbon TiO2 produced by thermolysis of MIL-125-NH2 under an inert atmosphere for enhanced visible light photocatalytic activity

Metal-organic frameworks have gained significant attention as precursors for the synthesis of functional materials with tailored properties. In this study, we present the synthesis and characterization of nitrogen-doped porous carbon TiO2 (N-C/TiO2) by thermolysis of MIL-125-NH2. The effect of calcination temperature (ranging from 300 to 900°C) and atmospheric conditions on the phase transition, elemental composition and morphological structure is thoroughly investigated. Through X-ray diffraction (XRD) analysis, we identified the formation of the rutile phase in the N-C/TiO2 nanoporous structure, which leads to the creation of oxygen vacancies and metal defects. Interestingly, the orthorhombic shape of MIL-125-NH2 is retained in the final N-C/TiO2 product, indicating the robustness of the conversion process. The UV-Vis diffuse reflectance (UV-Vis) and photoluminescence (PL) analysis demonstrated that the phase transition results in a narrowed band gap energy and reduced recombination of photogenerated electron-hole pairs. The photocatalytic activity of the synthesized N-C/TiO2 is evaluated by the degradation of methylene blue (MB) dye under visible light irradiation. Our results revealed that superoxide radicals are the primary species responsible for the photocatalytic reaction. Furthermore, the N-C/TiO2 photocatalyst exhibits excellent stability and recyclability for five consecutive photocatalytic cycles. Overall, this study provides novel insights into the synthesis, characterization and photocatalytic activity of N-C/TiO2 material derived from MIL-125-NH2, emphasizing the significance of calcination temperature and atmospheric conditions. The developed N-C/TiO2 poses great potential for various environmental and energy applications where enhanced visible light photocatalytic activity is desired.

4,4′-([2,2′-Bithiophene]-5,5′-diylbis(ethyne-2,1-diyl))bis(1-methylpyridin-1-ium) Iodide

Viologens are a highly advantageous class of compounds for the synthesis of functional materials. Owing to their versatile structure, they can embed additional conjugated moieties, thus representing a convenient platform, for example for organic semiconductors and other energy-related uses. A straightforward synthesis of an extended viologen containing a bithiophene is described here, together with its UV-visible absorption and fluorescence spectroscopy, showing multiple absorption and emission bands. Thanks to its ease of synthesis and optical properties, this organic salt appears to be of potential interest for various optoelectronic applications.

Highly sensitively detection of amine vapors released during shrimp spoilage by fluorescent molecules locked in covalent organic frameworks.

The fluorescent sensors allow sensitive detection of amine vapors for assessing the safety and quality of seafood products. However, high diffusion resistance and insufficient recognition sites usually limit the sensitivity of the sensors. Here, we employed an emulsion-confined assembly strategy to uniform encapsulate fluorescent molecules perylene diimide (PDI) molecules into covalent organic frameworks (COFs) to achieve ultrasensitive detection of amine vapors. The detection mechanism is based on the photoinduced electron transfer from amine to the excited PDI. This method exhibits a broad linear detection range from 8ppb to 800ppm and the limit of detection reaches as low as 1.2ppb. The real-time detection of the amine vapors produced during shrimp spoilage is successfully achieved with excellent performance. This provides a versatile method for the on-demand synthesis of functional materials with high fluorescence properties for the development of chemical sensors via encapsulating different fluorescent molecules into COFs.

Cooperativity at the Solution/Solid Interface: Formation and Reactivity of Self-Assembled Monolayers

Cooperativity is a molecular phenomenon, in which multiple interactions participate synchronously to significantly affect the activity and/or selectivity of the interacting components by accelerating (or impeding) their chemical or physical processes. Cooperative effects are prevalent in biology and can be observed in chemistry and materials science. Synthesis of functional materials frequently requires surfaces and interfaces where cooperative interactions can propagate with substrate assistance. In this context, of great interest is the characterization and control of ligands binding to metal centers, given their rich chemistry and prevalence in functional materials. In addition, self-assembly of compounds on surfaces can be steered by cooperative effects, and supramolecular polymerization can also proceed in a cooperative manner. Essential for these kinds of chemistries is the availability of highly resolving analysis methods to investigate reaction and adsorption outcomes directly at the surface. Scanning tunneling microscopy (STM) is particularly well suited to the study of such processes on surfaces and interfaces by offering both molecular resolution and real time and space information regarding changes in the electronic structure of materials upon adsorption and/or reaction.In this contribution, we present quantitative STM experimental results and supporting theoretical calculations of the binding dynamics of neutral ligands (heteroaromatics, O2) to metal porphyrins adsorbed on solid substrates as well as self-assembly of polyaromatics on metallic supports. Single molecule level STM imaging was accomplished in-situ under ambient solution conditions. We measured binding affinities and uncovered surface modulated cooperativity both in coordination reactions and in molecular self-assembly -- results essential for understanding adsorbate-surface interactions. Computations corroborate our experimental findings. The high-resolution, quantitative knowledge gained at the molecular level combined with theoretical studies offer not only insights into chelation, adsorption, and cooperativity but also into control parameters for surface-driven synthesis, tunable surface functionalization, and catalysis selectivity control.

A potential nonlinear optical material for crown-porphyrin complexes: Alkali metal doping and transition metal introducing

Crown ethers have inspired the rapid growth of research interest in the design and synthesis of functional materials due to their exceptional affinity for metal. In this work, a fascinating crown-porphyrin (Cr-Pr) complexes were studied with doping alkali metal (potassium, K atom) on the crown ether face and introducing transition metal (zinc, Zn atom) on the porphyrin face. The research reveals that the Cr-Pr complex with doped K and Zn atoms results in significant variations in nonlinear optical (NLO) properties. Interestingly, the crown ether ring with the K atom in the K@Cr-Pr complex leads to a remarkable first hyperpolarizability (βtot). On the contrary, when introducing the Zn atom in porphyrins, the Cr-Pr@Zn complex exhibits no significant change in NLO response. Further, the combination of the K and Zn atoms in crown-porphyrin complex (K@Cr-Pr@Zn) can result in significant enhancement of their NLO characteristics, which is much greater than that of the K@Cr-Pr and the Cr-Pr@Zn complexes. The natural population analysis (NPA) and the molecular electrostatic potential maps (ESP) show that the doping of the K atom regulates effectively charge distribution in the complexes. Moreover, the great βtot value can be further illustrated by their low transition energies and an obvious charge transfer (CT) transition in the main excited states. Therefore, the current work achieves that the NLO properties of crown ether derivatives can be regulated by doping alkali metals in the crown ether ring and provides a theoretical guide for developing high-performance NLO devices.

Ultrasonics and sonochemistry: Editors’ perspective

Ultrasonic waves can induce physical and chemical changes in liquid media via acoustic cavitation. Various applications have benefitted from utilizing these effects, including but not limited to the synthesis of functional materials, emulsification, cleaning, and processing. Several books and review articles in the public domain cover both fundamental and applied aspects of ultrasonics and sonochemistry. The Editors of the Ultrasonics Sonochemistry journal possess diverse expertise in this field, from theoretical and experimental aspects of acoustic cavitation to materials synthesis, environmental remediation, and sonoprocessing. This article provides Editors’ perspectives on various aspects of ultrasonics and sonochemistry that may benefit students and early career researchers.

Development of a novel wear-resistant WC-reinforced coating based on the case-hardening steel Bainidur AM for the substitution of carburizing heat treatments

Laser-based directed energy deposition of metals (DED-LB/M) supports the synthesis of functional materials with tailored properties and performance through in-situ modification of the alloying composition within the processing zone. In this investigation, a low-alloyed steel was modified stepwise to analyse the influence of carbon and tungsten carbide (WC) addition on the resulting material properties. A moderate carbon concentration of 0.4 wt.-% improved the average hardness (520 HV0.5). WC particles on the other hand were dissolved within the matrix and resulted in a fine microstructure with high hardness (780 HV0.5). A combined addition of carbon and WC led to the highest material hardness (840 HV0.5). Scratch tests showed that the wear resistance rises with increasing hardness but is improved the most by the addition of hard particles. Furthermore, these tests revealed an anisotropic abrasive wear resistance which correlates with the direction of the weld tracks. Loading the material parallel to the weld track direction led to a homogeneous wear. When the material is scratched perpendicularly to the weld tracks, an inhomogeneous wear with periodic characteristics occurred. The periodicity can be explained by the different microstructural characteristics and hardness at the transition zone between adjacent weld tracks deposited in DED-LB/M. For all materials, the transition between two weld tracks was characterized by a columnar microstructure with low microhardness while the adjacent weld tracks possessed a finer microstructure and higher microhardness. These microstructural differences were mirrored in scratch testing since wear peaks can be observed at the transition zone between two weld tracks.

Unusual Increasing Viscoelasticity of Wormlike Micelles Composed of Imidazolium Gemini Surfactants with Temperature

The viscoelasticity of wormlike micelles composed of ionic surfactants typically shows an exponential decrease with increasing temperature, which limits their application in relatively high-temperature (>90.0 °C) oilfields and the synthesis of functional materials as supramolecular templates at high temperatures. In this work, a series of imidazolium gemini surfactants, 1,9-(ethane-1,2-diyl)bis(3-alkyl-1H-imidazol-3-ium) bromide ([Cn-2-Cnim]Br2, n = 12, 14, 16, 18, 20), were synthesized. Their surface activities and aggregation behaviors in water were studied by electrical conductivity, rheology, polarization optical microscopy, small-angle X-ray scattering, ζ potential, and hydrogen nuclear magnetic resonance measurements. [C12-2-C12im]Br2 and [C14-2-C14im]Br2 mainly precipitate in water. [Cn-2-Cnim]Br2 (n = 16, 18, 20) forms lamellar liquid crystals over a large range of concentrations at low temperatures. With the increase of temperature, the lamellar liquid crystals transit to wormlike micelles. Interestingly, the viscoelasticity of the three wormlike micelles first increases to the maximum and then decreases with increasing temperature. These wormlike micelles without additives retain high viscoelasticity up to 90.0 °C or above. With the increase of the alkyl chain length of the surfactants, the transition temperature of lamellar liquid crystal to wormlike micelles and the disintegration temperature of wormlike micelles increase. The unusual increase of the viscoelasticity of wormlike micelles was due to the desorption of weakly bound counterions and the extension of the long hydrophobic chains of surfactants at high temperatures.

Alkynone β-trifluoroborates: A new class of amine-specific biocompatible click reagents.

Amine-targeting reactions that work under biocompatible conditions or in water are green processes that are extremely useful for the synthesis of functional materials and biotherapeutics. Unfortunately, despite the usefulness of this reaction, there are very few good amine-specific click methods reported thus far. Here, we report an amine-specific click reagent using alkynone β-trifluoroborates as the electrophiles. These boron-containing alkynyl reagents exhibit extremely high chemoselectivity toward amines even in the presence of thiols. The resulting oxaboracycle products are bench-stable, displaying the reactivities of both organoborates and enaminones. Intrinsic advantages of this methodology include benign reaction conditions, operational simplicity, remarkable product stability, and excellent chemoselectivity, which satisfy the criteria of click chemistry and demonstrate the high potential in bioconjugation. Hence, this water-based chemical approach is also applicable to the modification of native amino acids, peptides, and proteins. Ultimately, the essential role of water during the reaction was elucidated.

A novel template processing method for preparing spinel oxides with various morphologies to assemble high-performance supercapacitors

With the increasing complexity of the application scenarios of nanomaterials, transition metal oxides (TMOs) have shown excellent development potential. However, the synthesis of TMOs with customized morphologies for different application environments is still challenging. Herein, an acid-alcohol treatment based on the different intensities of the redox reactions between nitric acid and ethanol was developed to prepare different carbon templates. Through impregnation and annealing of the templates, NiCo2O4 (NCO) materials with hollow spherical (NCO-HS), multi-shell spherical (NCO-MS), and lamellar (NCO-L) morphologies were obtained. The characterization was performed through different analytical methods, which revealed various structures, morphologies, and surface chemistry of the materials. NCO-HS, NCO-MS, and NCO-L were tested for supercapacitor applications and exhibited a high specific capacitance of 402.6, 1037.1, and 531.4 F g−1, respectively. Overall, the proposed method can be used to customize the synthesis of functional materials with various morphologies for future advanced applications.

One‐step fabrication of moon‐shaped microrobots through in situ solidification of magnetic Janus droplets in microchannels

AbstractSpecial‐shaped microscale structures have shed light on new possibilities in key fields of chemistry, medicine, and energy. Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions, drug delivery, and functional material synthesis. Microfluidic‐based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control. Specifically, Janus droplets are generated in microfluidic chips featuring a flow‐focusing configuration. Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions, where the portion containing magnetic nanoparticles is solidified through the UV‐initiated polymerization process right after the formation while the Janus structure is left intact. We succeed in controlling the morphology of the Janus droplet along with the moon‐shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields, which are characterized and quantified by three‐dimensional profile measurement and high‐speed microparticle velocimetry measurement. Our proposed on‐chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale, which could shed light on new possibilities in key fields of controlled chemistry reaction, medicine synthesis, and energy generation.

Microcurrent behavior of core-shell droplet deposition in coaxial electrohydrodynamic printing

The core–shell droplets have the characteristics of stable micro-environment, small volume, large specific surface, which means wider application prospects in micro reactors, functional material synthesis and other fields. However, how to realize the controllable preparation of high flux, high resolution and small size for core–shell droplets is still the key point to be broken through. In this paper, the coaxial electrohydrodynamic printing (EHD) technology is used to combine the real-time microcurrent signal with the behavior characteristics of core–shell droplets, both achieve the interface behavior characteristics of the nozzle droplets to be analyzed and clarify the microcurrent behavior when the core–shell droplets are generated. At the same time, the influence of the inner and outer solution supply rate on the core–shell droplet was investigated. When the supply rate of inner solution changes from 10 μl/h increases to 90 μl/h, the average current increased from 0.0153 μA to 0.0652 μA, but also the droplet generation frequency raised by 14 times, moreover, the average diameter of droplets could be reduced by half. In contrast, the change of outer shell supply rate has less influence on the average current, generation frequency and diameter of droplets. This research provides a possibility for controllable high resolution of core–shell droplet EHD printing, which can be helpful significantly to improve the functional characteristics of the macroscopic and microstructure of the core–shell droplet.