Water-soluble Core Research Articles

Interfacial Polymerization Depth Mediated by the Shuttle Effect Regulating the Application Performance of Pesticide-Loaded Microcapsules.

The highly water-soluble nematicide fosthiazate is anticipated to undergo microencapsulation in order to enhance its retention around plant roots and mitigate leaching into groundwater. However, the underlying mechanism governing the influence of hydrophilicity of the microcapsule (MC) core on the evolution of the microcapsule shell remains unclear, posing challenges for encapsulating water-soluble core materials. This study elucidates the microlevel formation mechanism of microcapsules by investigating the impact of interfacial mass transfer on shell formation and proposes a method for regulating the structure of shells. The study reveals that enhancing the hydrophilicity of the core enhances the shuttle effect between the oil and aqueous phase, expands the region of polymerization reactions, and forms a loose and thick shell. The thickness of the microcapsule shell prepared using solvent oil 150# (MCs-SOL) measures only 264 nm, while that of the microcapsules prepared using propylene glycol diacetate and solvent oil 150# at a ratio of 2:1 (MCs-P2S1) is 5.2 times greater. The enhanced compactness of the shell reduced the release rate of microcapsules and the leaching distance of fosthiazate in soil, thereby mitigating the risk of leaching loss and facilitating the distribution of active ingredients within crop roots. The MCs-SOL had a limited leaching distance measurement of 8 cm and exhibited a satisfactory efficacy of 87.3% in controlling root galling nematodes. The thickness and compactness of the MCs shell can be regulated by manipulating the interfacial shuttle effect, providing a promising approach to enhancing utilization efficiency while mitigating potential environmental risks.

Dopamine-mimetic-coated polyamidoamine-functionalized Fe3O4 nanoparticles for safe and efficient gene delivery

Fe3O4 nanoparticles (NPs) are widely used in the construction of drug and gene delivery vectors because of their particular physicochemical properties. Surface modification can not only reduce the cytotoxicity of Fe3O4, but also further improve the biocompatibility and delivery efficiency. In this work, firstly, polydopamine (PDA)-coated Fe3O4 NPs (named Fe3O4@PDA) were prepared by using the self-polymerization characteristics of dopamine in alkaline environment. Then, polyamidoamine (PAMAM) was modified by the Michael addition reaction to prepare water-soluble core—shell magnetic NPs of Fe3O4@PDA@PAMAM, and its potential as gene vector was further evaluated. The results revealed that Fe3O4@PDA@PAMAM had the ability to condense and protect DNA, and showed lower cytotoxicity, higher cell uptake and transfection efficiency than those of PAMAM. It has the potential to become a magnetic targeted gene vector for further study.

A Water-Soluble Core for Manufacturing Hollow Injection-Molded Products.

To manufacture a complicated hollow product without any assembly process, for example, the plastic intake manifold, is difficult by the traditional injection molding method. The fusible-core technique, which uses a low-melting-point alloy as a sacrificial core, was developed to solve this problem; however, the limited selection of resin type and the huge capital investment have caused this technique to spread slowly. In this work, a novel method is established that can produce similar products without the limitation of resin type, as well as a lower-energy-consumption process. The concept of the enveloped core defined by a water-soluble core assembled with a shell is proposed herein; it provides both rigidity and toughness to resist the pressure during the injection molding process. The shape of the enveloped core equals the internal contour of the designated product. An insert molding process was introduced to cover the enveloped core with a skin layer. Cut out the end of the enveloped core and immerse it into a water bath. When the water-soluble core inside the shell is dissolved, the product with a special internal contour is accomplished. A tee-joint is presented to demonstrate how the proposed method can be utilized. The optimal ingredient of the core and processing parameters are determined by the Taguchi method. The result shows that the proposed product is molded successfully when the compressive strength of the core is larger than 2 MPa. In addition, the eccentricity measurement of internal contour of the optimal sample exhibits a 56% improvement, and the required time for the core removal is less than 154 s.

Microencapsulated soil conditioner with a water-soluble core: improving soil nutrition of crop root

Traditional level of fertilisers was used by most farmers in China with the risks about resources wasting, environmental pollution together with soil structure deterioration. It is practicable to tackle the challenges about over-fertilisation and low efficiency with microencapsulated soil conditioner (MSC), which clads the water soluble core with natural polymer. Fulvic acid (FA) can be used as core material, because it possesses the characteristics of water-soluble, fertiliser maintenance and expedient monitoring. The morphology, structure, and properties of MSC were studied and compared. The particle size of MSC was ranged from 1.58 to 2.14 mm with a similar shape which was obtained by conventional measuring method due to their soft features. This was mainly attributed to the concentration of liquid paraffin and the interaction between shell materials and calcium chloride. FTIR spectra showed that a peak appeared at 1372 cm−1, and this was ascribed to the microcapsules crosslinked and solidified by calcium ions. Sustained release experiment revealed that the microcapsules owned better fertiliser-retaining and water-retaining performances, and FA may be released as long as 750 h. Biodegradation experiments revealed that an obvious pore structure was found on the surface of microspheres after 30 d of degradation, and this was consistent with the sustained release experiment. Pot experiment illustrated that the plants cured with the microcapsules showed significant growth trend and grew up to 9.2 cm with a maximum rate, and this revealed that MSC owned better performance of promoting the growth of crop root.

Effects of Composition on the Physical Properties of Water-Soluble Salt Cores

The demand for producing essential cast parts and the design requirements for superior engineering performance have increased in recent years. Sand cores used in conventional aluminum cast parts are harmful to the environment, which limits their application. Utilizing water-soluble cores in the aluminum casting industry is expected to be an environmentally friendly approach due to recyclability of the salt cores. In this study, water-soluble salt cores were made from chloride- and/or carbonate-containing salts in various amounts. The salts were melted and cast into steel molds to obtain salt cores. The salt cores were subjected to three-point bending tests to determine their mechanical strength, the melting points were determined with thermal analyses, and the water solubility was measured at room temperature and 50 °C. A maximum bending strength of 17.19 MPa, a maximum melting point of 776 °C and a maximum water solubility of 89 g salt/100 ml water were obtained for the samples with compositions of 75% KCl–25% K2CO3 and 25% Na2CO3–75% K2CO3, respectively. Fractographs of the samples used in bending tests were taken by a still camera in macro mode, and from these fractured surfaces, scanning electron microscopy studies were performed. The X-ray diffraction pattern of the sample exhibiting optimal properties (28.3% Na2CO3 and 71.7% K2CO3) also showed that K2CO3, NaKCO3 and KNaCO3 phases were present in the structure, as expected. An actual casting process with aluminum die casting of an automotive part was also performed. The diecast aluminum part was subjected to a leak-proof test, and X-ray images were used to check for porosity in the part.

Novel method for microencapsulation of oxalic acid with ethyl cellulose shell for sustained-release performance

In this study, a novel method was employed for the coacervation of ethyl cellulose (EC) that was induced by polydimethylsiloxane to achieve the encapsulation of oxalic acid (OA). The prepared OA microcapsules were used to delay an in-situ exothermic reaction between ammonium chloride (NH4Cl) and sodium nitrite (NaNO2) during hydraulic gel fracturing for oil extraction. The chemical compositions and crystalline structures of the microcapsules were investigated by Fourier-transform infrared spectroscopy and X-ray powder diffraction analysis, respectively. Scanning electron microscopy and optical microscopy measurements showed that the microcapsules exhibited perfect core-shell structures. The layer-by-layer mode of coating coacervated EC on the OA was also indicated by optical microscopy. The sustained-release performance of the microcapsules could be regulated by adjusting the core/shell ratio. The sustained-release time required to attain the concentration peak of OA microcapsules prepared at a core/shell ratio of 1:2 was 185 min, as analyzed by UV–vis spectroscopy at room temperature. Further, the catalytic performances of OA microcapsules for a model system of in-situ exothermic hydraulic gel fracturing were investigated. Thus, a novel method to microencapsulate water-soluble core materials within EC shells was explored. It was shown that the prepared OA@EC microcapsules possessed suitable sustained-release properties.

One Pot, Rapid and Green Photo-Chemical Synthesis of Ag2S and Ag2S-ZnS Core–Shells

Water soluble Ag2S and Ag2S-ZnS core–shells were prepared using a photochemical approach by means of 12 W UV lamp with 250–400 nm wavelengths. Energy dispersive x-ray spectrometry and elemental mapping confirmed the uniform formation of quantum dots (QDs). X-ray Diffraction and Transmission Electron Microscope characterizations were employed to confirm the formation of Ag2S and Ag2S-ZnS core-shells with sizes about 3 nm and 10 nm, respectively. Fourier transform infrared spectroscopy indicated that UV illumination results in good attachment of 3-mercaptopropionic acid (MPA) to the surface of Ag2S QDs. Photoluminescence measurements showed a strong emission around 870 nm with photoluminescence quantum yields of about 3.8% and 4.6% for Ag2S and Ag2S-ZnS core-shells, respectively. This green method of synthesis using MPA together with their rather high emission yield is promising for the application for in vivo bio-imaging.

A copper-free click reaction for the synthesis of redox-responsive water-soluble core cross-linked nanoparticles for drug delivery in cancer therapy

Copper-free click reaction for synthesis of redox-responsive water-soluble polymer based core cross-linked nanoparticles for cancer therapy.

Microparticles for sustained release of water-soluble drug based on a containment, dry coating technology.

Controlled release microparticles in a sub-gram-scale batch were fabricated using a ball mill, dry coating technique, to coat the water-soluble core material. This process also guaranteed the maintenance of the containment's integrity during the dry coating process. Quinine (average diameter, ca. 10 μm) and carnauba wax were used as the core and coating material, respectively. We evaluated the influence of process time, milling speed, and quinine-to-carnauba wax ratio on the particle size of the coated particles and their in vitro drug release profiles. Scanning electron microscopic observations suggested that the small wax particles attached to the core (quinine) particles resulted in a smooth film during the dry coating process. The size distribution of the coated particles agreed with the theoretically estimated size distribution. The in vitro release test demonstrated that the coated particles released quinine over 2 h in a biphasic mode. These results suggest that dry coating of microparticles less than 50 µm (D99) is feasible on a several-grams-batch scale. This new ball mill-coating technique also enables a guaranteed containment, a prerequisite for the manufacturing of highly bioactive or biohazard substances.

A water-soluble core material for manufacturing hollow composite sections

This paper presents the development of a low-cost water-soluble core material, which is suitable for producing hollow composite structures via high pressure moulding processes, such as compression moulding and resin transfer moulding. The bulk material of the core is sodium chloride (NaCl), which is held together by a water-soluble trehalose binder. The composition of the core has been optimised to provide acceptable dissolution rates and mechanical properties for high volume structural composite applications.The compressive strength of the NaCl core was 57MPa at ambient temperature, which reduced to 20MPa when tested at 120°C. The compressive strength at elevated temperature was approximately 4times higher than for a water-soluble commercial benchmark and 33times higher than a conventional structural closed-cell foam. The specific dissolution rate of the NaCl core was between 0.14 and 1.23kg/(min·m2), depending on processing parameters and the coefficient of thermal expansion was approximately 43×10−6/K. A practical example has been presented to demonstrate how the removable core can be used to produce a representative hollow section of an integrally stiffened panel.

Effect of kaolin on tensile strength and humidity resistance of a water-soluble potassium carbonate sand core

Water soluble cores (WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559% (after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.

Combining Additive Manufacturing with Advanced Composites for Highly Integrated Robotic Structures

The combination of additive manufacturing with advanced composites offers potentials in the development of highly integrated lightweight structures. This paper investigates a novel manufacturing process route where binder jetting is used to produce a water soluble sand core for hand layup of autoclave prepreg composites. The novel approach is applied to a hollow high performance robotic part demonstrating the following two design potentials: First, binder jetting of water soluble sand material is a suitable technology for the production of very complex composite parts at low tooling costs. Second, tailored load introduction elements made of selective laser melting enable lightweight designs. Weight savings of 54.3% compared to a state-of-the-art aluminum robotic part indicate that the approach is competitive for complex low volume parts.

Water-Soluble Multimodal Core/ Shell NaGdF4:Yb,Er@NaGdF4 Upconverting Nanoparticles for Cancer Diagnostics

Water-Soluble Multimodal Core/ Shell NaGdF4:Yb,Er@NaGdF4 Upconverting Nanoparticles for Cancer Diagnostics Upconverting nanoparticles (UCNPs) are promising new generation of imaging probes capable of working as theranostic agents. Upconversion is a nonlinear optical process that converts two or more photons to a higher-energy out-put photon. UCNPs are guesthost systems where trivalent lanthanide ions are dispersed as a guest in an appropriate dielectric host lattice with a dimension less than 30nm. Generally, upconversion emission arises from 4f-4f orbital electronic transitions.

Redox Photocatalysis with Water-Soluble Core–Shell CdSe-ZnS Quantum Dots

The use of CdSe-ZnS type I quantum dots as redox photocatalysts with visible light in water is investigated by monitoring the oxidation reaction of 8-oxo-2′-deoxyguanosine and the reduction of nitrophenylalanine derivatives. The detection of reaction intermediates and the identification and quantitation of reaction products establish that both reactions are photocatalyzed simultaneously by CdSe-ZnS type I quantum dots. The photocatalyzed reactions are observed without the need for sacrificial reactants and with high turnover numbers (>400). These results demonstrate that CdSe-ZnS type I quantum dots can work efficiently as redox photocatalysts in water solution.

Water-Soluble Core–Shell Hyperbranched Polymers for Enhanced Oil Recovery

Novel water-soluble core–shell hyperbranched polymers (HBPAMs), consisting of nano-SiO2 as the core, hyperbranched polyamidoamide (PAMAM) as the subshell, and linear hydrophilic chains as the outermost layer, were synthesized through an in situ free-radical polymerization strategy. The PAMAM hybrid nano-SiO2, which is preferentially modified by 3-aminopropyltriethoxysilane, was prepared by successively repeating the Michael addition of methyl acrylate and amidation reaction of ethylenediamine. By varying the numbers of functionalized branch-cell units, the numbers of outmost linear hydrophilic chains can be tuned with the mean diameter being 462 nm for HBPAM-1 and 573 nm for HBPAM-2. Rheological measurements demonstrated that HBPAMs were classical power law fluids, and the critical shear rate shifts toward the higher region as the number of linear hydrophilic chains of the outermost shell increase. The intersection modulus and relaxation time were elaborately calculated. Static experiments convincingly pr...

PH-degradable and thermoresponsive water-soluble core cross-linked polymeric nanoparticles as potential drug delivery vehicle for doxorubicin

Doxorubicin release at preferred lysosomal pH of the cancer cells due to pH-induced de-crosslinking of polymer nanoparticle core.

A novel method to prepare water-soluble core microcapsules with controlled burst release

The controlled burst release of water-soluble materials from microcapsules is very important in many practical applications. A novel method is described to synthesize microcapsules containing water-soluble materials, ammonium persulfate or sodium nitrite, as the core and a hydrophobic copolymer (P(St–MMA)) as the shell through an evaporation–dispersion–polymerization process. The microcapsules had an average size of 8–16 μm. The release behavior was examined at different temperatures, pH values and salinities. The release pattern of the cores from the microcapsules was burst release. After a given time period in the 10–45 h region, all of the cores could be completely released within 1 h from the microcapsules. The structures, dispersion and morphologies of the microcapsules were characterized before and after they were stored for 5 months at room temperature. This method further enhances the potential of microcapsules with burst release properties for practical applications.

Coaxial electrospinning for encapsulation and controlled release of fragile water-soluble bioactive agents.

Coaxial electrospinning is a robust technique for one-step encapsulation of fragile, water-soluble bioactive agents, including growth factors, DNA and even living organisms, into core-shell nanofibers. The coaxial electrospinning process eliminates the damaging effects due to direct contact of the agents with organic solvents or harsh conditions during emulsification. The shell layer serves as a barrier to prevent the premature release of the water-soluble core contents. By varying the structure and composition of the nanofibers, it is possible to precisely modulate the release of the encapsulated agents. Promising work has been done with coaxially electrospun non-woven mats integrated with bioactive agents for use in tissue engineering, in local delivery and in wound healing, etc. This paper reviews the origins of the coaxial electrospinning method, its updated status and potential future developments for controlled release of the class of fragile, water-soluble bioactive agents.

Influence of chemical composition, form and morphology of surface of NaCl grains on mechanical properties of water soluble cores

With development of a number of branches (automobile industry) the demand of increasingly more complex and more exacting castings that are mechanically cleanable with difficulties only is growing. Application of the technology of disposable water soluble cores from inorganic salts is one of solutions of troublesome problems of removing the cores from places hardly accessible for cleaning. Solubility in water enables reversal crystallization of the salt from the water solution what is a precondition for forming a closed ecological cycle of the core manufacture. Application of salt cores can be met in processes of low-pressure casting, gravity casting in dies, and in connection with just running research project in pressure castings from Al-alloys. The article brings results of checking the cores made from cooking salts (NaCl) predominantly available on the Czech market. It is aimed at two main technologies (shooting and high-pressure squeezing) of their manufacture and it investigates the influence of chemical composition, form and morphology of the grain surface on mechanical properties (bending strength) of water soluble salt cores for their application for high-pressure die casting of Al-alloys.

Preparation of Temperature and Water Responsive Microcapsules Containing Hydroquinone with Spray Drying Method

It was tried to prepare temperature and water responsive microcapsules containing hydroquinone as a water soluble core material with the spray drying method. Microcapsules were composed of ethyl cellulose (EC), methyl cellulose (MC) and P-N-isopropylacrylamid (PNIPAM). P-N-isopropylacrylamid and methyl cellulose were used as a temperature responsive polymer and as a water responsive polymer, respectively. Ethyl cellulose was the main shell material of microcapsule. At the microencapsulation process, the core and shell materials were dissolved in ethyl alcohol dissolving water (20 wt%) and then, spray-dried to prepare microcapsules. In the fundamental operation, the concentration and molecular weight of methyl cellulose were mainly changed. The releasing rate of hydroquinone was repressed at 40°C and increased at 20°C due to temperature responsive PNIPAM. Furthermore, responsibility to water was increased with the concentration of methyl cellulose.