THE PREPARATION AND CHARACTERIZATION OF SBR/PS CORE-SHELL PARTICLES BY GAMMA IRRADIATION

A kind of core(SBR)-shell(PS)particles was synthesized by using SBR latex and grafting with St under gammairradiation.The influences of absorbed dose and dose rate on the grafting yield of PS on SBR seed latex have beeninvestigated.Results show there was a transition layer which contained the SBR/PS graft copolymer between the SBR coreand PS shell.Dynamic laser scattering(DLS)and differential scanning calorimetry(DSC)results confirm the existence ofgrafted polystyrene,and transmission electron microscope(TEM)observation verifies the core-shell structure of SBR-g-PSlatex.Such SBR/PS core-shell latex could be processed easily to ultrafine rubber powders by using spray drying andexpected to be used as an impact modifier for PS.

TOUGHENING OF POLYCARBONATE WITH PBA-PMMA CORE-SHELL PARTICLES

The miscibility,mechanical properties,morphology and toughening mechanism of PC/PBA-PMMA blends wereinvestigated.The dynamic mechanical results show that PC/PBA-PMMA blend has good miscibility and strong interfacialadhesion.The Izod impact strength of blend PC/PBA-PMMA with 4%(volume fraction)PBA-PMMA core-shell modifier is16 times higher than that of pure PC.The core-shell volume fraction and thickness of the PMMA shell have effect on thetoughness of PC/PBA-PMMA blends.As PMMA volume fraction increases,the toughness of PC/PBA-PMMA blendincreases,and reaches a maximum value at 30% volume fraction of PMMA or so.The tensile properties of PC/PBA-PMMAblend with a minimum amount of PBA-PMMA modifier show that brittle-tough transition has no significant variance incomparison with that of pure PC.The scanning electron microscopic(SEM)observation indicates that the tougheningmechanism of the blend with the pseudo-ductile matrix modified by small core-shell latex polymer particles is the synergeticeffect of cavitation and shear yielding of the matrix.

Optimized high performance liquid chromatography–ultraviolet detection method using core-shell particles for the therapeutic monitoring of methotrexate

Methotrexate （MTX） is an antineoplastic drug, and due to its high toxicity, the therapeutic drug mon- itoring is strictly conducted in the clinical practice. The chemometric optimization and validation of a high performance liquid chromatography （HPLC） method using core-shell particles is presented for the determination of MTX in plasma during therapeutic monitoring. Experimental design and response surface methodology （RSM） were applied for the optimization of the chromatographic system and the analyte extraction step. A Poroshel1120 EC-C18 （3.0 mm × 75 mm, 2.7 μm） column was used to obtain a fast and efficient separation in a complete run time of 4 min. The optimum conditions for the chroma- tographic system resulted in a mobile phase consisting of acetic acid/sodium acetate buffer solution （85.0 mM, pH =4.00） and 11.2% of acetonitrile at a flow rate of 0.4 mL/min. Selectivity, linearity, accuracy and precision were demonstrated in a range of 0.10-6.0 μM of MTX. The application of the optimized method required only 150μL of patient plasma and a low consumption of solvent to provide rapid re- sults.

Controlling Shell Thickness of PS/SiO_2 Core-Shell Particles and Their Crystallization into 3-D Ordered Thin Film

PS/SiO2 particles with core-shell structure were synthesized by coating silica on surface of polystyrene(PS) colloidal particles.The reaction parameters,such as initial tetraethyl orthosilicate(TEOS) concentration,water concentration and reaction temperature,have been investigated to control the thickness of silica shells.The shell thickness was prepositional to the square root of the initial concentration of TEOS and first increased with increasing water concentration,reached a maximum at about 2.0 mol/L and then started decreasing beyond that concentration.It was also found that the shell thickness decreased firstly with the reaction temperature added,then tended to a constant.The so-synthesized PS/SiO2 core-shell particles were directly crystallized into 3-D ordered thin film,then sintered at 570℃ into the ordered macroporous thin film.Compared with the conditional method,the present approach avoids repeatedly filling the precursor in the templetes and save time more.

Core-shell particles of C-doped CdS and graphene: A noble metal-free approach for efficient photocatalytic H_(2) generation

To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H_(2) generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H_(2) under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H_(2) generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(N_(D))in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate)from narrow disperse polymer particles by surface-initiated atom transferradical polymerization(ATRP)was investigated.Polydivinylbenzene(PDVB)particles were prepared by dispersionpolymerization with poly(N-vinyl pyrrolidone)(PVP)as the stabilizer.Chloromethylated PDVB was used as initiating coresites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system.It was found that poly(methylmethacrylate)was grafted not only from the particle surfaces but also from within a thin shell layer,leading to particles sizeincreases from 2.38-3.00 μm with a core-shell structure particles.The grafted core-shell particles were characterized withFTIR,SEM,DSC.

Fe-N_(x) sites coupled with core-shell FeS@C nanoparticles to boost the oxygen catalysis for rechargeable Zn-air batteries

The development of efficient single-atom catalysts(SACs) for the oxygen reduction reaction(ORR)remains a formidable challenge,primarily due to the symmetric charge distribution of metal singleatom sites(M-N_(4)).To address such issue,herein,Fe-N_(x) sites coupled synergistic catalysts fabrication strategy is presented to break the uniform electronic distribution,thus enhancing the intrinsic catalytic activity.Precisely,atomically dispersed Fe-N_(x) sites supported on N/S-doped mesoporous carbon(NSC)coupled with FeS@C core-shell nanoparticles(FAS-NSC@950) is synthesized by a facile hydrothermal reaction and subsequent pyrolysis.Due to the presence of an in situ-grown conductive graphitic layer(shell),the FeS nanoparticles(core) effectively adjust the electronic structure of single-atom Fe sites and facilitate the ORR kinetics via short/long-range coupling interactions.Consequently,FAS-NSC@950displays a more positive half-wave potential(E_(1/2)) of 0.871 V with a significantly boosted ORR kinetics(Tafel slope=52.2 mV dec^(-1)),outpacing the commercial Pt/C(E_(1/2)=0.84 V and Tafel slope=54.6 mV dec^(-1)).As a bifunctional electrocatalyst,it displays a smaller bifunctional activity parameter(ΔE) of 0.673 V,surpassing the Pt/C-RuO_(2) combination(ΔE=0.724 V).Besides,the FAS-NSC@950-based zincair battery(ZAB) displays superior power density,specific capacity,and long-term cycling performance to the Pt/C-Ir/C-based ZAB.This work significantly contributes to the field by offering a promising strategy to enhance the catalytic activity of SACs for ORR,with potential implications for energy conversion and storage technologies.

Magnetic core-shell microparticles for oil removing with thermal driving regeneration property

Here, we report the construction of magnetic core-shell microparticles for oil removal with thermal driving regeneration property. Water-in-oil-in water (W/O/W) emulsions from microfluidics are used as templates to prepare core-shell microparticles with magnetic holed poly (ethoxylated trimethylolpropane triacrylate) (PETPTA) shells each containing a thermal-sensitive poly (N-Isopropylacrylamide) (PNIPAM) core. The microparticles could adsorb oil from water due to the special structure and be collected with a magnetic field. Then, the oil-filled microparticles would be regenerated by thermal stimulus, in which the inner PNIPAM microgels work as thermal-sensitive pistons to force out the adsorbed oil. At the same time, the adsorbed oil would be recycled by distillation. Furthermore, the adsorption capacity of the microparticles for oil keeps very stable after 1st cycle. The adsorption and regeneration performances of the microparticles are greatly affected by the size of the holes on the outer PETPTA shells, which could be precisely controlled by regulating the interfacial forces in W/O/W emulsion templates. The optimized core-shell microparticles show excellent oil adsorption and thermal driving regeneration performances nearly without secondary pollution, and would be a reliable green adsorption material for kinds of oil.

Polybutylacrylate/poly (methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part Ⅱ Toughness on DGEBA/DDM system

Mechanlcal properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hundred parts of epoxy resin by weight). The impact strength of modified systems increased apparently with the decrease of core sizes. However, the shearing strength changed gently with the particle sizes. CSEP with lightly crosslinked rubbery core showed more effectiveness on toughness than others. With solution blending, CSEP could be dispersed in epoxy matrix well, and the morphologies of dispersed rubber domains were controlled perfectly by CSEP whose structure was predesigned. A cavitation-shearing band toughness mechanism was observed from the SEM micrographs of fracture surface. It also was found that the deforming temperature (DT) of modified epoxy did not decline apparently.

Templating core-shell particles using metal ion-chelating biosurfactants

Designer biosurfactants can be used to stabilise and functionalise interfaces.One particularly promising use is the stabilisation of oil-in-water emulsions,enabling fine tuning physical,chemical and biological surface properties.The ability of emulsion systems to carry high payloads makes them attractive for applications in medicine,food and fragrances,and cosmetics.However,they have limited long-term stability.Here we sought to use the metal ion-chelating ability of the biosurfactant peptide,AM1,to precipitate the formation of a gold metal shell on AM1-stabilised emulsions by electroless plating.We found that replacing the commonly used zinc(Ⅱ)with palladium(Ⅱ)for coordination by histidine residues of adjacent AM1 peptides produced interfacial films that maintained elasticity at acidic pH.Proton NMR suggested a coordination mechanism independent of the imidazole ring of the histidines.Nevertheless.stabilisation of emulsions at low pH enabled the deposition of a gold shell,albeit by an unexpected mechanism.We propose that gold nanoparticles forming in bulk are adsorbed onto the peptide-stabilised interface,accumulating into a particulate coating.The resulting one-step method for nanoparticle precipitation and shell formation will be useful for the creation of biocompatible core-shell particles for applications where large payloads of hydrophobic active compounds require stability over long time periods.

Poly(methyl methacrylate)/Poly(N-isopropylacrylamide) Core-Shell Particles Prepared by Seeded Precipitation Polymerization: Unusual Morphology and Thermo-sensitivity of Zeta Potential

Poly（methyl methacrylate）/poly（N-isopropylacrylamide） （PMMA/PNIPAM） core-shell particles were synthesized by seeded precipitation polymerization of N-isopropylacrylamide （NIPAM） in the presence of PMMA seed particles. The anionic potassium persulfate was used as initiator, and acrylic acid as functional comonomer. It was shown that the weight ratio of the PNIPAM shell to the PMMA core can be greatly increased through continuous addition of NIPAM monomer at a relatively slow rate. PMMA/PNIPAM particles with different shell thickness were obtained by varying the amount of charged NIPAM monomers. These particles exhibited unique nonspherical core-shell morphology. PMMA core was partially coated by dense hair-like or antler-like PNIPAM shell depending on the shell thickness. The measurement of these particles＇ zeta potential at different temperatures showed that the absolute value of zeta potential unusually decreased as the particle size decreased with temperature.

Synthesis of Core-shell ZSM-5@ Ordered Mesoporous Silica by Tetradecylamine Surfactant

A core-shell composite consisting of ZSM-5 zeolite as the core and ordered mesoporous silica as the shell was prepared by a surfactant-controlled sol-gel process and using tetradecylamine(TDA) as the template and Tetraethylorthosilicate(TEOS) as the silica precursor.The pores of the silica shell were found to be ordered and perpendicular to the crystal faces of the zeolite core.The thickness of the shell in the coreshell structured composite can be adjusted in the range of 20-90 nm,while the surface morphology and the pore size distribution were modified by changing the mass ratio of TEOS to zeolite.The composite molecular sieves have higher surface area for capturing molecules than ZSM-5,and with the increase of mesoporous shell layer,the ZSM-5@SiO_(2)-x composites show stronger adsorption capacity of butyraldehyde.However,when the shell thickness exceeds 90 nm,the adsorption capacity of butyraldehyde decreases instead.The composites have a huge potential for environmental applications.

Review:Progress in Core-shell Rubber Particles for Efficiently Toughening Resins

Core-shell toughening particles are structured composite particles consisting of generally two different components, one at the center as a rubbery elastic core and surrounding by the second as a glassy inelastic shell. The design, preparation, and application of core-shell polymer particles have been briefly reviewed. Morphological characteristics of the core-shell particles by transmission electron microscopy(TEM) and scanning electron microscopy(SEM) are focused. The vital factors that are useful to control core-shell morphology and toughening properties including core-shell monomer species, polymerization conditions, cross-linking reagents, synthetic method, and post-processing techniques are analyzed. Distinguished properties are mainly considered as the most desirable features that endow core-shell polymer particles with various applicabilities, particularly as effectively toughening components in brittle epoxy resin and polylactide that are substrate of copper clad laminate widely used in the modern electronic world and environmentally friendly materials that are useful as packaging films, disposable tableware, biomedical equipment, and new energy vehicles.

Computer vision-aided DEM study on the compaction characteristics of graded subgrade filler considering realistic coarse particle shapes

The compaction quality of subgrade filler strongly affects subgrade settlement.The main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse particles.First,an improved Viola-Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade filler.Shape indexes of 2D subgrade filler are then computed and statistically analyzed.Finally,numerical simulations are performed to quantitatively investigate the effects of the aspect ratio(AR)and interparticle friction coefficient(μ)on the macro-and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method(DEM).The results show that with the increasing AR,the coarse particles are narrower,leading to the increasing movement of fine particles during compaction,which indicates that it is difficult for slender coarse particles to inhibit the migration of fine particles.Moreover,the average displacement of particles is strongly influenced by the AR,indicating that their occlusion under power relies on particle shapes.The dis-placement and velocity of fine particles are much greater than those of the coarse particles,which shows that compaction is primarily a migration of fine particles.Under the cyclic load,the interparticle friction coefficientμhas little effect on the internal structure of the sample;under the quasi-static loads,however,the increase inμwill lead to a significant increase in the porosity of the sample.This study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.

Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes.This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble column.Particle image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared.The results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening methods.Compared with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.

A novel Ag/ZnO core-shell structure for efficient sterilization synergizing antibiotics and subsequently removing residuals

The massive use of antibiotics has led to the aggravation of bacterial resistance and also brought environmental pollution problems.This poses a great threat to human health.If the dosage of antibiotics is reduced by increasing its bactericidal performance,the emergence of drug resistance is certainly delayed,so that there's not enough time for developing drug resistance during treatment.Therefore,we selected typical representative materials of metal Ag and semiconductor ZnO nano-bactericides to design and synthesize Ag/ZnO hollow core-shell structures(AZ for short).Antibiotics are grafted on the surface of AZ through rational modification to form a composite sterilization system.The research results show that the antibacterial efficiency of the composite system is significantly increased,from the sum(34.7%+22.8%-57.5%)of the antibacterial efficiency of AZ and gentamicin to 80.2%,net synergizes 22.7%,which fully reflects the effect of 1+1>2.Therefore,the dosage of antibiotics can be drastically reduced in this way,which makes both the possibility of bacterial resistance and medical expenses remarkably decrease.Subsequently,residual antibiotics can be degraded under simple illumination using AZ-self as a photocatalyst,which cuts off the path of environmental pollution.In short,such an innovative route has guiding significance for drug resistance.

Exploring the Core-shell Structure of BaTiO3-based Dielectric Ceramics Using Machine Learning Models and Interpretability Analysis

A machine learning(ML)-based random forest(RF)classification model algorithm was employed to investigate the main factors affecting the formation of the core-shell structure of BaTiO_(3)-based ceramics and their interpretability was analyzed by using Shapley additive explanations(SHAP).An F1-score changed from 0.8795 to 0.9310,accuracy from 0.8450 to 0.9070,precision from 0.8714 to 0.9000,recall from 0.8929 to 0.9643,and ROC/AUC value of 0.97±0.03 was achieved by the RF classification with the optimal set of features containing only 5 features,demonstrating the high accuracy of our model and its high robustness.During the interpretability analysis of the model,it was found that the electronegativity,melting point,and sintering temperature of the dopant contribute highly to the formation of the core-shell structure,and based on these characteristics,specific ranges were delineated and twelve elements were finally obtained that met all the requirements,namely Si,Sc,Mn,Fe,Co,Ni,Pd,Er,Tm,Lu,Pa,and Cm.In the process of exploring the structure of the core-shell,the doping elements can be effectively localized to be selected by choosing the range of features.

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

Significance of including lid thickness and particle shape factor in numerical modeling for prediction of particle trap efficiency of invert trap

Sediment accumulation on the bed of open sewers and drains reduces hydraulic efficiency and can cause localized flooding.Slotted invert traps installed underneath the bed of open sewers and drains can eliminate sediment build-up by catching sediment load.Previous three-dimensional(3D)computational studies have examined the particle trapping performance of invert traps of different shapes and depths under varied sediment and flow conditions,considering particles as spheres.For two-dimensional and 3D numerical modeling,researchers assumed the lid geometry to be a thin line and a plane,respectively.In this 3D numerical study,the particle trapping efficiency of a slotted irregular hexagonal invert trap fitted at the flume bottom was examined by incorporating the particle shape factor of non-spherical sewage solid particles and the thicknesses of upstream and downstream lids over the trap in the discrete phase model of the ANSYS Fluent 2020 R1 software.The volume of fluid(VOF)and the realizable k-turbulence models were used to predict the velocity field.The two-dimensional particle image velocimetry(PIV)was used to measure the velocity field inside the invert trap.The results showed that the thicknesses of upstream and downstream lids affected the velocity field and turbulent kinetic energy at all flow depths.The joint impact of the particle shape factor and lid thickness on the trap efficiency was significant.When both the lid thickness and particle shape factor were considered in the numerical modeling,trap efficiencies were underestimated,with relative errors of-8.66%to-0.65%in comparison to the experimental values of Mohsin and Kaushal(2017).They were also lower than the values predicted by Mohsin and Kaushal(2017),which showed an overall overestimation with errors of-2.3%to 17.4%.

Core-shell mesoporous carbon hollow spheres as Se hosts for advanced Al-Se batteries

Incorporating a selenium(Se)positive electrode into aluminum(Al)-ion batteries is an effective strategy for improving the overall battery performance.However,the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products.In this work,we aim to harness the advantages of Se while reducing its limitations by preparing a core-shell mesoporous carbon hollow sphere with a titanium nitride(C@TiN)host to load 63.9wt%Se as the positive electrode material for Al-Se batteries.Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN,the obtained core-shell mesoporous carbon hollow spheres coated with Se(Se@C@TiN)display superior utilization of the active material and remarkable cycling stability.As a result,Al-Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g^(-1)at a current density of 1000 mA·g^(-1)while maintaining a discharge specific capacity of 86.0 mAh·g^(-1)over 200 cycles.This improved cycling performance is ascribed to the high electrical conductivity of the core-shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.