Electrostatic Spray Research Articles

Core-Shell Microspheres Prepared Using Coaxial Electrostatic Spray for Local Chemotherapy of Solid Tumors.

Local chemotherapy is an alternative therapeutic strategy that involves direct delivery of drugs to the tumor site. This approach avoids adverse reactions caused by the systemic distribution of drugs and enhances the tumor-suppressing effect by concentrating the drugs at the tumor site. Drug-loaded microspheres are injectable sustained-release drug carriers that are highly suitable for local chemotherapy. However, a complex preparation process is one of the main technical difficulties limiting the development of microsphere formulations. In this study, core-shell structured microspheres loaded with paclitaxel (PTX; with a core-shell structure, calcium alginate outer layer, and a poly (lactic acid-co-glycolic acid) copolymer inner layer, denoted as PTX-CA/PLGA-MS) were prepared using coaxial electrostatic spray technology and evaluated in vitro and in vivo. PTX-CA/PLGA-MS exhibited a two-stage drug release profile and enhanced anti-tumor effect in animal tumor models. Importantly, the preparation method reported in this study is simple and reduces the amount of organic solvent(s) used substantially.

Transparent-to-Brown-Black Patterned Electrochromic Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) exhibit promising electrochromic (EC) performance owing to their porous structure, regular channel, and tunable component characteristics. However, few reports focus on MOF materials with the EC performance of a transparent to brown-black (neutral colored state) change that is more suitable for smart windows. In this work, we proposed a strategy for synthesizing MOF (named Ni-BPY) EC materials and corresponding films fabricated via a low-cost electrostatic spray deposition technique. The obtained film exhibits excellent EC performance with a neutral color change from transparent to brown-black, a large optical modulation of 70% at 430 nm, and a fast response within 10 s. Benefiting from good electrical and chemical stability, the Ni-BPY film can be cycled over 500 times. Notably, the Ni-BPY MOF film also delivers a stepwise-controlled process during the bleached state due to its porous characteristics. In addition, the unique color variation of the Ni-BPY film derives from the redox reaction of the Ni metal node between Ni2+ and Ni3+, which is verified by the in situ potential-dependent Raman and X-ray photoelectron spectroscopy (XPS) measurement. As a proof of application, the patterned Ni-BPY EC films and devices are additionally constructed to demonstrate their potential application in electronic tags and logo displays.

Preparation of block copolymer PS-b-PFPE and its application on cotton fabric electrostatic microsphere spraying

Preparation of block copolymer PS-b-PFPE and its application on cotton fabric electrostatic microsphere spraying

Electrostatic Spray Deposition of Al-Doped ZnO Thin Films for Acetone Gas Detection

In this study, pure ZnO and Al-doped ZnO(AZO) thin films were coated onto a SiO2 wafer using the electrostatic spray deposition (ESD) process for acetone gas detection under laboratory conditions. Voltage levels were varied to determine the optimal conditions for producing thin films with the highest uniformity. The results indicate that the optimal coating voltage for achieving the highest uniformity of the coated films is 2.9 kV for ZnO and 2.6 kV for AZO. The thin films were produced under these optimal ESD conditions by adjusting the coating time, and gas sensors were fabricated by printing electrodes using a reverse offset process on top of the thin films. Analysis of the sensing response revealed that the AZO-coated gas sensor with a 200 s deposition exhibited the best acetone-sensing ability at 300 °C, with a maximum response of 13.41 at 10 ppm. Furthermore, the fabricated gas sensors effectively detected acetone gas even at a low concentration of 2 ppm, demonstrating high selectivity in comparison to other gases.

Enhanced separation performance of composite nanofiltration membranes via electrostatic air spray PSS/PEI interlayer

Thin-film composite (TFC) membranes with an interlayer were prepared extensively for desalination, but the hydrophilicity and permeability were not well improved. In this work, a smooth and hydrophilic interlayer was constructed by electrostatic air spray deposition (EASD) of poly (sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) on the polyethersulfone substrate and an ultra-thin separation layer was prepared using interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) to acquire high-performance composite nanofiltration (NF) membranes. The polymer solution was atomized into tiny particles under a high-pressure electrostatic air spray effect, facilitating the deposition of PSS/PEI with good homogeneity and enabling a denser and smoother interlayer surface. The introduction of PSS/PEI enhanced the hydrophilicity of TFC membranes and increased the repulsion of divalent cations to improve the salt rejection. The impacts of PEI concentration and EASD time on the separation performance of NF membrane were explored. The optimized TFC-3 NF membrane had a permeate flux of 74.5 ± 1.6 L·m−2·h−1 under 0.5 MPa, which was 2.5 times higher than the water flux of conventional TFC-0 membrane, while retaining up to 99.2 ± 0.5 % of Na2SO4. This work provides a prospective strategy to develop high-performance TFC membranes with great extensive progress for seawater purification.

Electrostatic Spraying Microspheres of Nano Boron and Its Constant-Volume Combustion with Potassium Nitrate

ABSTRACT The nanometer boron (nB) powders have become the most promising high-energy additive in the field of fuel-rich solid propellants due to their extremely high gravimetric and volumetric calorific value. However, further applications are limited by its disadvantages such as easy agglomeration, easy oxidation, high ignition temperature, and incomplete energy release. Herein, nB powders were pre-agglomerated into microspheres by electrostatic spray method using fluoropolymer (F2602) as binders. The morphology and structure of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET). Results showed that the pre-agglomerated nB microspheres had good dispersion, high sphericity, and no surface oxide. The thermal performance and combustion performance of the samples were characterized by a synchronous thermal analyzer and combustion pressure test device. Results showed that the nB microspheres had the highest oxidation weight gain within 1000°C and lowest activation energy compared to the same scale micron boron. In addition, the microspheres significantly shorten the combustion time and improve the combustion efficiency.The pressurization rate of nB microspheres is 4.12 times that of micron boron powders and 2.85 times that of nB powders. These excellent properties may be related to its unique spherical porous structure. Therefore, the preparation of nB microspheres with controllable structure by electrostatic spraying has a good application prospect.

Statistical investigations into automated spray‐applied stripe coats to complex geometries of floating offshore wind foundations

AbstractThe automation of coating processes allows consistent, economical, and ecological applications. In this study, the effects of various surface geometries—steel plates, plates with weld seams, plates with bolts, and plates with welded fillets—on the uniformity of dry film thickness (DFT) after robotic stripe coating applications with an electrostatic spray device are investigated and analyzed with statistical methods. Robot traverse rate, pump pressure, and voltage. Based on analysis of variance studies, the robot traverse rate was identified to be the most influential factor. For plates with weld seams, an optimization study was conducted, resulting in a multiresponse prediction model. The model achieved a DFT within the target range across all measuring points within a 95% confidence interval. At an optimized factor combination (117 mm/s, 0.3 MPa, 61.4 kV), the DFT values ranged between 100 and 142 µm. The findings of this study provide fundamentals for achieving uniform coating distributions on complex geometries and for optimizing process parameters.

Enhancing mechanical properties of selectively laser sintered SiC/Si composites printed using electrostatic spraying microspheres with fine particles

The SiC/Si composites were prepared via selective laser sintering (SLS) combined with reactive melt infiltration (RMI) of liquid Si, using fine SiC particles with original particle sizes of 0.05, 0.8 and 5 μm. A novel electrostatic spraying combined with phase inversion (ES-PI) method was developed to assemble SiC particles into spherical powders (40–60 μm in diameter) before SLS, enabling SiC with excellent flowability. Commercial coarse SiC microparticles (∼40 μm) were also adopted to prepare the SiC/Si reference composite for comparison. Then the effects of the fine original particle sizes of SiC on the microstructures, as well as mechanical performance of composites were studied. Compared to commercial SiC microparticles, the ES-PI SiC microspheres show superior sphericity and fluidity but a relatively high porosity. However, the pores in ES-PI SiC microspheres, which are potentially detrimental to mechanical properties of composites, will be totally filled and eliminated in the SiC/Si composites after RMI. The mechanical performance of the SiC/Si composites printed using the fine nano (0.05 μm) and submicron (0.8 μm) original particles was effectively improved than the reference composite. When printed using the ES-PI SiC microspheres with 0.05 μm original particles, the flexural strength of the SiC/Si composite was enhanced by 25 %. This is attributed to the cracks deflection as well as the fracture mode transition from transgranular to intergranular rupture by the use of nano- or submicro-sized original SiC particles. This work provides an effective solution for preparing high strength SiC/Si composites with fine nano- or submirco particle sizes for space-based lightweight optical mirror using SLS.

Preparation of drug-loaded microspheres with a core-shell structure using silk fibroin and poly lactic-co-glycolic acid and theirapplication.

Advances in bone tissue engineering offer novel options for the regeneration of bone tissue. In the current clinical treatment, the method of accelerating bone tissue regeneration rate by promoting early angiogenesis has been widely accepted. This study aimed to develop a long-acting slow-release system using the pro-angiogenic drug tetramethylpyrazine (TMPZ) and pro-osteogenic drug icariin (ICA), which can be administered locally to achieve the sequential release of TMPZ and ICA for better clinically efficiency in the treatment of bone defects. This study aimed to prepare microspheres with a core-shell structure using two polymers, poly lactic-co-glycolic acid and silk fibroin, by coaxial electrostatic spraying. Based on the therapeutic model for bone defects, the pro-angiogenic drug TMPZ and pro-osteogenic drug ICA were encapsulated in the shell and core layers of the microspheres, respectively. Subsequently, TMPZ and ICA were released sequentially to promote early angiogenesis and late osteogenesis, respectively, at the site of the bone defect. The optimal preparation parameters for preparing the drug-loaded microspheres were identified using the univariate controlled variable method. Additionally, microsphere morphology and core-shell structure, such as physical properties, drug-loading properties, invitro degradation and drug release patterns, were characterised using scanning electron microscope and laser scanning confocal microscopy. The microspheres prepared in this study were well-defined and had a core-shell structure. The hydrophilicity of the drug-loaded microspheres changed compared to the no-load microspheres. Furthermore, invitro results indicated that the drug-loaded microspheres with high encapsulation and loading efficiencies exhibited good biodegradability and cytocompatibility, slowly releasing the drug for up to three months. The development of the drug delivery system with a dual-step release mechanism has potential clinical applications and implications in the treatment of bone defects.

Cellulose acetate superhydrophobic coatings for efficient oil–water separation using a combination of electrostatic spraying and chemical vapor deposition

AbstractThe efficient and simple separation of oil–water mixtures has been a global challenge due to the growing problem of oily wastewater. To address this issue, various materials with special wetting properties and functionality have been developed in the past decades for oil–water separation. In this study, a superhydrophobic cellulose acetate (CA) functional coating was prepared by electrostatic spraying of CA and chemical vapor deposition of methyltrichlorosilane (MTCS) on a stainless steel mesh (SSM). Water contact angle in air (WCA) of the resulting coating is154° or more, and oil under water contact angle (UWOCA) is 0°. Simultaneously, the separation flux of the resulting coating for oil–water mixtures is as high as 23977.77 L·m−2·h−1, with separation efficiencies exceeding 99%. Due to its excellent water repellency, the CA functional coating can effectively separate oil and water, and can be easily dried for continuous use. Furthermore, the CA functional coating exhibits good stability in salt solutions and acidic environments, making it an ideal material for addressing oily wastewater challenges.Highlights The coating obtained by electrostatic spraying and CVD was superhydrophobic. The separation flux and separation efficiencies of coatings is 23977.77 L·m−2·h−1 and 99%. Coatings remain stable under polar environment conditions (pH = 2–12 and NaCl = 1–3 mol/L).

Preparation of wettability-controlled surface by electrostatic spray deposition to improve performance uniformity of small molecule/polymer blend organic field-effect transistors

Preparation of wettability-controlled surface by electrostatic spray deposition to improve performance uniformity of small molecule/polymer blend organic field-effect transistors

Dielectric polyimide composites with enhanced thermal conductivity and excellent electrical insulation properties by constructing 3D oriented heat transfer network

With the continuous development of electronic technology, polymer-based thermal management materials (TMMs) with insulation, high thermal conductivity (TC), and low dielectric performance are urgently needed for electronic devices. Nevertheless, balancing above expected properties is still a daunting challenge because of phonon scattering and interfacial polarization. Here we put forward a simple and useful method for preparing polyimide (PI) composites. First, the alignment of modified boron nitride nanosheet (MBN) along the fiber was controlled by electrospinning, while silver nanowire (AgNW) was utilized for electrostatic spraying to overlap the AgNW with MBN. Finally, a hybrid network oriented along the horizontal direction was formed by hot-pressing. The in-plane TC of the PI composites was up to 8.38 W/mK due to the formation of thermal conduction pathways along the hybrid network. The PI composites also had a series of merits, such as electrical insulation of over 2.40 × 1014 Ω cm, low dielectric constant (3.84), low dielectric loss (<0.01) at 106 Hz, excellent thermal stability (THRI = 299.3 °C), and heat dissipation capability. These PI composites with satisfactory comprehensive properties have great application potential in electronic devices, particularly in flexible electronic devices or circuits that demand electrical insulation and high TC.

Paint Film Formation Characteristics on Conical Surfaces for Electrostatic Air Spray Painting

When a curved target surface is coated in an electrostatic spray-painting process, the paint film pattern on curved targets will deform, and the thickness will change compared with the planar target due to the curvature characteristics of the target, the inhomogeneous electric field, and the flow field. Therefore, directly using the planar deposition distribution for painting the trajectory planning of curved surfaces causes large errors and low paint transfer efficiency. A study investigating the curved surface paint film thickness distribution characteristics is presented in this research to understand the relations among the target surface curvature, the electrostatic field, and the flow field distribution. Spray-painting process simulations were performed for conical surfaces of different curvatures. Moreover, the paint particle’ trajectories, electric potential, and film deposition distribution were computed using ANSYS Fluent. The paint transfer efficiencies of these targets were computed. The results show that when the generatrix curvature of the conical surface increases gradually, the electric field intensity near the wall increases, which enhances the deposition of charged droplets on the wall. Moreover, the airflow field velocity increases as the curvature increases, which leads to a large diffusions of the spray flow field, so the paint thickness decreases, and the transfer efficiency is low.

An Experimental Investigation on the Effects of the Base Fluid of External Fluid and Voltage on the Milling Performance of Nanofluid Composite Electrostatic Spraying

An Experimental Investigation on the Effects of the Base Fluid of External Fluid and Voltage on the Milling Performance of Nanofluid Composite Electrostatic Spraying

Quality evaluation of tomatoes coated by an advanced electrostatic spray coating system

SummaryA critical assessment was carried out to investigate the impact of electrostatic spray coatings as compared to dip coatings on tomatoes which were conducted at 30 ± 2 °C and 60% RH for a period of 30 days. In this paper, the impact of developed polysaccharide‐based coatings (alginate and cellulose coatings with clove oil) and commercially available wax‐based coatings (VMW50+) was compared to that of uncoated tomatoes. The application of alginate‐ and cellulose‐based electrostatically charged sprays was found to significantly (P &lt; 0.05) reduce the weight loss, firmness, colour and bioactive compound degradation and overall flavour loss as compared to uncoated and dip‐based coating during the storage period of 30 days. Moreover, alginate‐ and cellulose‐based electrostatically charged spray coating were more efficient in delaying the spoilage of tomatoes by 20 days as compared to the uncoated one. A significant level of charge‐to‐mass ratio has been achieved, which confirmed the chargeability of coating materials. These findings confirmed the capability of electrostatically charged sprays to extend the shelf life and preserve the overall quality of tomatoes during storage.

Anticorrosion mechanism of ethylene-chlorotrifluoroeethylene coatings reinforced with hydroxylated carbon nanotubes: An experimental and molecular dynamics simulation study

Carbon nanotubes/ethylene-chlorotrifluoroeethylene (CNT/ECTFE) composite coatings were prepared on the surface of carbon steel via electrostatic spraying and low temperature heat treatment. The influence of hydroxylated carbon nanotubes on the anticorrosive properties of ECTFE coatings during water penetration stage was investigated through characterization tests of the coating micromorphology, phase structure, hydrophilicity/hydrophobicity, microhardness and electrochemical corrosion performance. Additionally, simulation analysis of the coating internal structure and water molecular infiltration law by molecular dynamics was conducted. The results indicate that the addition of CNT can augment the efficacy of ECTFE coating against water penetration, thereby improving the corrosion protection performance. This is primarily attributed to the ability of CNT to reinforce structural stability by impeding the free movement of ECTFE molecular segments and obstructing water molecules from infiltrating. Meanwhile, the hydroxyl groups on the surface of CNT can capture a large number of water clusters through hydrogen bonding and restrict the infiltration of water molecules by occupying osmotic channels. In addition, CNT can prolong the penetration path of water through the labyrinth effect.

Preparation of pH Sensor Based on Extended-Gate Field-Effect Transistor with Spinel ZnCo2O4 Thin Films by Electrostatic Spray Deposition

Preparation of pH Sensor Based on Extended-Gate Field-Effect Transistor with Spinel ZnCo2O4 Thin Films by Electrostatic Spray Deposition

Drug Release and Biocompatibility of a Paclitaxel-Coated Balloon Prepared Using the Electrostatic Spray Method

Paclitaxel-coated balloons (PCBs) have become effective treatment options for vascular disease, but long-term drug release and biocompatibility are influenced by the drug patterns. In this work, paclitaxel coatings were prepared via electrostatic spraying, and the effect of D-tartaric acid additives was investigated. Microstructures and surface morphology were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Drug release was measured in vitro, and biocompatibility was evaluated using the haemolysis rate, platelet adhesion and activation, protein adsorption, cell adhesion, and cell proliferation. Our results showed that a uniform crystalline paclitaxel drug coating was obtained, and that the pattern and release of paclitaxel was influenced by the content of D-tartrate. The contact angle of all coatings was less than that of nylon 12. The drug coatings prepared at a mass ratio of paclitaxel to D-tartaric acid of 2:1 had the highest drug release in a brief period of time. The haemolysis rate of the drug coating was less than 5%. Compared with the control samples, platelet adhesion and activation were significantly reduced, albumin adsorption was increased, and the adsorption of fibrinogen was reduced on the surface of the drug coating. Endothelial cells demonstrated good proliferation after three days of cell culture. Therefore, PCBs with specific patterns have good biocompatibility and drug release, with potential clinical applications in vascular disease.

Effect of pole piece structure on magnetic lens electrospinning system: Experimental and simulation study

Magnetic lenses can effectively reduce the fiber diameter and whipping-circle width to control the random behavior of electrospinning. Although the axisymmetric magnetic lens for electrostatic spinning have several potential applications, the effect of its pole-piece structure on the electrostatic spinning process has not been adequately discussed. In this study, we explored the influence of changing the pole piece structure of the magnetic lens on the electrospinning process using experimental and numerical simulation methods. The results showed that for a 12 wt% polyacrylonitrile (PAN) solution, when the applied voltage was 15 kV, the feed rate was 1 mL/h, and current of the magnetic lens was 1 A, the gap width of the magnetic lens had a notable effect on the fiber deposition efficiency of the electrostatic spinning range of the magnetic lens. Appropriately reducing the gap width in the range of 1–10 mm can effectively reduce the deposition range of the fibers and improve fiber film thickness. Furthermore, when the angle of α is 45°, it exerts the most significant effect on the electrostatic spinning spray range and deposition efficiency, and the fiber film thickness and average fiber diameter attain their highest values. When the angle of α increases or decreases from 45°, the fiber film thickness and fiber diameter both show a decreasing trend. A change in the magnetic lens structure can effectively change the ejection range and fiber diameter during electrostatic spinning, which shows great potential in the field of nanofiber production.

3D heterostructure constructed by few-layer 1T MoS2 and MXene under high electrostatic fields for high-performance supercapacitors

Electrostatic spray deposition (ESD) is a promising technique for preparing high-quality heterostructure materials to achieve high electrochemical performance. Moreover, the materials obtained by ESD possesses well-dispersed, bonder-free and easy-control advantages. Herein, we firstly report that 1T MoS2/Ti3C2Tx heterostructure material is successfully constructed by few-layer 1T MoS2 and Ti3C2Tx MXene through ESD. The construction of heterostructure by high electrostatic fields is able to solve problem of agglomeration of layered materials, improve conductivity and stabilize 1T MoS2 to realize outstanding electrochemical performance of supercapacitor. As expected, the binder-free 1T MoS2/Ti3C2Tx heterostructure displays an excellent specific capacitance (1198 mF cm−2 at 3 mA cm−2), a high rate performance (45% as current density from 3 to 20 mA cm−2) and long-cycle life (73.8% capacity retention after 7000 cycles at 20 mA cm−2). More interestingly, a simple and efficient route to prepare 2D/2D heterostructure electrode for storing energy can be extended to other materials.