Monodisperse microspheres (mean diameter 200-300 nm) with polystyrene cores and poly(acrylamide-co-butyl methacrylate) shells were prepared by using a free radical polymerization method. Moreover, the effect of mi...Monodisperse microspheres (mean diameter 200-300 nm) with polystyrene cores and poly(acrylamide-co-butyl methacrylate) shells were prepared by using a free radical polymerization method. Moreover, the effect of mixed solvent on the preparation, morphology and monodispersity was investigated. The experimental results showed that solubility parameter of butyl methacrylate and solvent affected mainly the molding of monodisperse core-shell microspheres. When the microspheres were fabricated in a sequential synthesis process, addition of hydrophilic and organic solvent including butyl methacrylate led to spherical degree of the particles becoming worse, and the mean diameter of the microspheres decreased and the monodispersity became better with increasing the crosslinker methylenebisacrylamide dosage.展开更多
CoFe2O4 nanoparticles (NPs) were synthesized by coprecipitation method using FeCl3·6H2O and CoCl2·6H2O as precursors.The synthesized conditions were optimized,such as added means of precipitator,quantity o...CoFe2O4 nanoparticles (NPs) were synthesized by coprecipitation method using FeCl3·6H2O and CoCl2·6H2O as precursors.The synthesized conditions were optimized,such as added means of precipitator,quantity of precipitator,the mol ratio of Fe 3+ to Co2+,reaction temperature and pH value.The synthesized material was characterized by XRD,TEM,FTIR,EDS,Raman and its magnetic properties were studied by VSM.The experimental results confirm that the sample is cubic spinel structure CoFe2O4 with a narrow size distribution and a good dispersion feature.CoFe2O4 NPs with well-controlled shape and size was obtained at 70℃.The magnetic properties indicate superparamagnetic behavior and good saturated magnetization.展开更多
The preparation process of electrically conductive filler for anisotropic conductive adhesive was performed and discussed.The spherical filler contains tri-layer structures: resin core,Ni-P intermediate coating layer,...The preparation process of electrically conductive filler for anisotropic conductive adhesive was performed and discussed.The spherical filler contains tri-layer structures: resin core,Ni-P intermediate coating layer,Au outer coating layer.The 4 μm resin spherical cores were synthesized by monodispersion polymerization method.Then they were contributed to electrical conductivity by electrolessly plating Ni-P layer and gold layer.These particles have good corrosion resistance,high stability,and enough mechanical strength.When mixed with thermosetting epoxy resin to produce anisotropic conductive adhesive(ACA),it can realize a good conductive bonding between bumps on dies and pads on substrates.This environmentally friendly conductive material offers numerous advantages over conventional solder technology and is an ideal substitute for the lead-contained solder in electronics packaging.展开更多
Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat...Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat acetonitrile.The polymer particles had clean surfaces due to the absence of any added stabilizer.The size of the particlesranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014.The effects of monomer feed incopolymerization on the microsphere formation were described.The polymer microspheres were characterized by SEM andchlorinity elemental analysis.展开更多
Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized...Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized by means of Fourier transform infrared spectrum (FT-IR), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that the as-prepared products are titania glycolate submicrospheres with diameters of 230-330 nm. The average particle diameter is estimated to be about 280 nm. Ultrasonic treatment has an important influence on the morphology of the produced titania glycolates. After calcination at 450°C for 2 h, these titania glycolates were completely converted into anatase TiO2. The morphology of TiO2 particles was well reserved during the calcination process except for a reduction of 18% in the average particle size.展开更多
Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, res...Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.展开更多
Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized mo...Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized monodisperse poly(methacrylic monomer-divinylbenzene)microspheres containing epoxy,lauyl,carboxyl and hydroxyl functions can be fabricated by solvothermal precipitation copolymerization at 20%(mass)monomer loading with over 94%microsphere yield.The morphology and porosity of the obtained particles can be readily tuned by cosolvent-acetonitrile binary solvents.Addition of a small amount of cosolvent that has similar solubility parameter to that of the functional monomer can significantly improve the monodispersity of the obtained microspheres.When tetrahydrofuran was used as the co-solvent,the surface area of the highly porous microspheres achieved higher than 400 m^(2)·g^(-1).Solvothermal precipitation co-polymerization can be expected in scale-up fabrication of various monodisperse functional microspheres free of any surfactant and additive.展开更多
Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslin...Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslinker with 2,2'- azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.展开更多
Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray ...Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectrometer(XPS), Fourier transformation infrared spectroscopy (FTIR), and thermogravimetric analysis(TGA) were adopted to characterize and investigate the size, structure, composition, and the binding manners between organic capping agent TOPO and inorganic ZrO2 nanocores of the as-prepared nanoparticles. In addition, the nanoparticles were also studied to determine their solubility and relative stability. The experimental results show that the prepared nanoparticles contain about 25% organic capping shell TOPO, 75% inorganic ZrO2 nanocores, and can be easily dissolved and be stably disersed in non-polar organic solvents.展开更多
Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacanc...Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.展开更多
Monodisperse crosslinked polystyrene (CPS) particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene (DVB) into the reaction system after polystyrene (PS) pa...Monodisperse crosslinked polystyrene (CPS) particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene (DVB) into the reaction system after polystyrene (PS) particles grew to -80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature (Tg) of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.展开更多
Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reve...Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reverse (w/o) microemulsion method. The powder X-ray diffraction (XRD) pattern indicated that the obtained silver nanoparticles were of face-centered cubic structure. The results of the transmission electron microscopy (TEM) show that the final silver nanoparticles are of spherical structure with an average diameter of 15.2 nm and of a Gaussian distribution. The internal high-ordered structure of silver nanoparticles was characterized by the field-emission high-resolution transmission electron microscopy (FEHRTEM), indicating that the silver is monocrystalline and it has only one nucleation site during the formation process of a nanoparticle. The time-resolved UV-visible absorption spectra was used to monitor the process of the reaction in situ. The results show that the concentration of silver nanoparticles increases but the size changes little and the morphology transforms from obvious ellipsoidal shape to nearly spherical shape during the process. The experimental results indicate that the droplets’ dynamic exchange which is closely related to the nature of surfactant film is the control factor of the kinetics. The dynamic exchange mechanism of silver nanoparticle formation is proposed to involve continual encounter of two separate droplets forming transient fused dimer in which the chemical reaction occurs followed by re-separation without combination. Attributed to the dual role of surfactant in the nanoparticle formation, tailored nanoparticles can be successfully synthesized in control in the premise of a certain stability of reverse microemulsion.展开更多
Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle eff...Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.展开更多
The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide (NMA), methyl methacrylate (MMA) and styrene (St) was successfully carried out under microwave irradiation, and monodisperse polymeric mi...The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide (NMA), methyl methacrylate (MMA) and styrene (St) was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating.展开更多
Magnetite (Fe3O4) nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the g...Magnetite (Fe3O4) nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.展开更多
In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysi...In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysis reveals that the monodisperse rigid sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400.Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-moleculel LDHs nanocomposites.展开更多
Spherical, monodispersed europium hydroxycarbonate particles wereobtained by homogeneous precipitation with urea in aqueous solution of Eu.(NO3)3at elevated temperature.The particles were readily converted to the unif...Spherical, monodispersed europium hydroxycarbonate particles wereobtained by homogeneous precipitation with urea in aqueous solution of Eu.(NO3)3at elevated temperature.The particles were readily converted to the uniformEu2O3 with average particle size of 50nm after calcined at 750℃.展开更多
The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-...The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.展开更多
In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS:Mn^2+ microspheres by using hydrothermal method and taking P123 surfactant as a ...In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS:Mn^2+ microspheres by using hydrothermal method and taking P123 surfactant as a template. The products were characterized by XRD, STEM, FT-IR and N2 adsorption-desorption. And the results show that the diameter of this microsphere is 1.0 μm or so, which is larger than that of ZnS microsphere without Mn^2+ doping, and it has monodispersion, smooth surface and uniform size, The doping of Mn^2+ does not obviously change the structure of monodispersed ZnS microsphere. The photoluminescence peak lies in a wide band ranging from 450 to 650 nm, and the microspheres emit orange light; with the increase of Mn^2+ concentration, fluorescence intensity of ZnS:Mn^2+ microsphere changes, and when the mole ratio of Mn^2+:Zn^2+ is 0.3:1, the fluorescence intensity is the strongest.展开更多
基金Funded by the National Natural Science Foundation of China (No. 20976202)
文摘Monodisperse microspheres (mean diameter 200-300 nm) with polystyrene cores and poly(acrylamide-co-butyl methacrylate) shells were prepared by using a free radical polymerization method. Moreover, the effect of mixed solvent on the preparation, morphology and monodispersity was investigated. The experimental results showed that solubility parameter of butyl methacrylate and solvent affected mainly the molding of monodisperse core-shell microspheres. When the microspheres were fabricated in a sequential synthesis process, addition of hydrophilic and organic solvent including butyl methacrylate led to spherical degree of the particles becoming worse, and the mean diameter of the microspheres decreased and the monodispersity became better with increasing the crosslinker methylenebisacrylamide dosage.
基金Funded by the National Natural Science Foundation of China(No.60877048)
文摘CoFe2O4 nanoparticles (NPs) were synthesized by coprecipitation method using FeCl3·6H2O and CoCl2·6H2O as precursors.The synthesized conditions were optimized,such as added means of precipitator,quantity of precipitator,the mol ratio of Fe 3+ to Co2+,reaction temperature and pH value.The synthesized material was characterized by XRD,TEM,FTIR,EDS,Raman and its magnetic properties were studied by VSM.The experimental results confirm that the sample is cubic spinel structure CoFe2O4 with a narrow size distribution and a good dispersion feature.CoFe2O4 NPs with well-controlled shape and size was obtained at 70℃.The magnetic properties indicate superparamagnetic behavior and good saturated magnetization.
基金The National Natural Science Foundation of China(No.10474024)NSFC-RGC Joint Research Scheme(No.60318002)+1 种基金Youth Chenguang Project of Science and Technology of Wuhan City of China(No.20065004116-10)StateKey Lab.of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology,No.WUT2004 M08)
文摘The preparation process of electrically conductive filler for anisotropic conductive adhesive was performed and discussed.The spherical filler contains tri-layer structures: resin core,Ni-P intermediate coating layer,Au outer coating layer.The 4 μm resin spherical cores were synthesized by monodispersion polymerization method.Then they were contributed to electrical conductivity by electrolessly plating Ni-P layer and gold layer.These particles have good corrosion resistance,high stability,and enough mechanical strength.When mixed with thermosetting epoxy resin to produce anisotropic conductive adhesive(ACA),it can realize a good conductive bonding between bumps on dies and pads on substrates.This environmentally friendly conductive material offers numerous advantages over conventional solder technology and is an ideal substitute for the lead-contained solder in electronics packaging.
基金This work was funded by the financial support of the National Natural Science Foundation of China(Project No.20274018)Nankai University.
文摘Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene)(poly(CMSt-co-DVB))microsphereswere prepared by distillation-precipitation copolymerization of chloromethylstyrene(CMSt)and divinylbenzene(DVB)inneat acetonitrile.The polymer particles had clean surfaces due to the absence of any added stabilizer.The size of the particlesranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014.The effects of monomer feed incopolymerization on the microsphere formation were described.The polymer microspheres were characterized by SEM andchlorinity elemental analysis.
文摘Monodisperse titania glycolate submicrospheres were synthesized by a modified sol-gel route, in which ultrasonic treatment was introduced to improve the reaction efficiency. The as-prepared products were characterized by means of Fourier transform infrared spectrum (FT-IR), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that the as-prepared products are titania glycolate submicrospheres with diameters of 230-330 nm. The average particle diameter is estimated to be about 280 nm. Ultrasonic treatment has an important influence on the morphology of the produced titania glycolates. After calcination at 450°C for 2 h, these titania glycolates were completely converted into anatase TiO2. The morphology of TiO2 particles was well reserved during the calcination process except for a reduction of 18% in the average particle size.
基金supported by the National Natural Science Foundation of China(No.30870679 and 30970787)National Basic Research Program of China(No.2006CB933206 and 2006CB705606)
文摘Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.
基金National Natural Science Foundation of China(51873079)for financial support。
文摘Simultaneous achievement in high solid content and high microsphere yield is deemed a challenge in the fabrication of monodisperse microspheres by precipitation polymerization.We herein demonstrate that micro-sized monodisperse poly(methacrylic monomer-divinylbenzene)microspheres containing epoxy,lauyl,carboxyl and hydroxyl functions can be fabricated by solvothermal precipitation copolymerization at 20%(mass)monomer loading with over 94%microsphere yield.The morphology and porosity of the obtained particles can be readily tuned by cosolvent-acetonitrile binary solvents.Addition of a small amount of cosolvent that has similar solubility parameter to that of the functional monomer can significantly improve the monodispersity of the obtained microspheres.When tetrahydrofuran was used as the co-solvent,the surface area of the highly porous microspheres achieved higher than 400 m^(2)·g^(-1).Solvothermal precipitation co-polymerization can be expected in scale-up fabrication of various monodisperse functional microspheres free of any surfactant and additive.
基金This work was supported in part by the National Science Foundation of China (No. 20504015)the starting project for young teachers from the Ministry of Education, China.
文摘Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslinker with 2,2'- azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.
基金Funded by the Natural Science Foundation of Shannxi Province of China(No.2010JM2016)the Foundation of Shannxi Educational Committee(No.2010JK469)
文摘Monodisperse ZrO2 nanoparticles capped by trioctylphosphine oxide (TOPO) were prepared in non-aqueous solvent using in-situ synthesis method. Transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectrometer(XPS), Fourier transformation infrared spectroscopy (FTIR), and thermogravimetric analysis(TGA) were adopted to characterize and investigate the size, structure, composition, and the binding manners between organic capping agent TOPO and inorganic ZrO2 nanocores of the as-prepared nanoparticles. In addition, the nanoparticles were also studied to determine their solubility and relative stability. The experimental results show that the prepared nanoparticles contain about 25% organic capping shell TOPO, 75% inorganic ZrO2 nanocores, and can be easily dissolved and be stably disersed in non-polar organic solvents.
基金financially supported by the National Key Research and Development Program of China(2017YFA0206500)NSFC(Grant Nos.21673198,91934303,21621091)。
文摘Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.
基金National Basic Research Program of China(Grant No:2006CB932601)the Scientific Research Foundation for Returned Overseas Chinese Scholar,Ministry of Education
文摘Monodisperse crosslinked polystyrene (CPS) particles were prepared through the normal emulsion polymerization method by adding crosslinker--divinylbenzene (DVB) into the reaction system after polystyrene (PS) particles grew to -80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature (Tg) of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.
文摘Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reverse (w/o) microemulsion method. The powder X-ray diffraction (XRD) pattern indicated that the obtained silver nanoparticles were of face-centered cubic structure. The results of the transmission electron microscopy (TEM) show that the final silver nanoparticles are of spherical structure with an average diameter of 15.2 nm and of a Gaussian distribution. The internal high-ordered structure of silver nanoparticles was characterized by the field-emission high-resolution transmission electron microscopy (FEHRTEM), indicating that the silver is monocrystalline and it has only one nucleation site during the formation process of a nanoparticle. The time-resolved UV-visible absorption spectra was used to monitor the process of the reaction in situ. The results show that the concentration of silver nanoparticles increases but the size changes little and the morphology transforms from obvious ellipsoidal shape to nearly spherical shape during the process. The experimental results indicate that the droplets’ dynamic exchange which is closely related to the nature of surfactant film is the control factor of the kinetics. The dynamic exchange mechanism of silver nanoparticle formation is proposed to involve continual encounter of two separate droplets forming transient fused dimer in which the chemical reaction occurs followed by re-separation without combination. Attributed to the dual role of surfactant in the nanoparticle formation, tailored nanoparticles can be successfully synthesized in control in the premise of a certain stability of reverse microemulsion.
基金supported by the National Natural Science Foundation of China(51974209)the Outstanding Doctoral Award Fund in Shanxi Province(20202017)。
文摘Lithium sulfur battery(LSB)is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid,while its wide commercialization is severely inhibited by the"shuttle effect"of polysulfides,low utilization of sulfur cathode,and safety of lithium anode.To overcome these issues,herein,monodisperse polar NiCo_(2)O_(4)nanoparticles decorated porous graphene aerogel composite(NCO-GA)is proposed.The aerogel composite demonstrates high conductivity,hierarchical porous structure,high chemisorption capacity and excellent electrocatalytic ability,which effectively inhibits the"shuttle effect",promotes the ion/electron transport and increases the reaction kinetics.The NCO-GA/S cathode exhibits high discharge specific capacity(1214.1 mAh g^(-1)at 0.1 C),outstanding rate capability(435.7 mAh g^(-1)at 5 C)and remarkable cycle stability(decay of 0.031%/cycle over 1000 cycles).Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate,while the chemical adsorption provided by polar NiCo_(2)O_(4)contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling.This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.
基金Funded by the Natural Science Foundation of Hubei Province (2010CDB04603)the Educational Commission of Hubei Province (Q200610004)
文摘The emulsifier-free emulsion polymerization of N-hydroxymethyl acrylamide (NMA), methyl methacrylate (MMA) and styrene (St) was successfully carried out under microwave irradiation, and monodisperse polymeric microspheres were prepared. The experimental results show that the emulsifier-free emulsion polymerization under microwave irradiation has more rapid reaction rate, higher conversion and shorter induction time than the copolymerization with conventional heating. The apparent activation energies are 61.04 and 83.75 kJ/mol, respectively; the microspheres have spherical morphology, and the microspheres prepared by emulsifier-free emulsion polymerization under microwave irradiation are smaller, more uniform than those obtained with conventional heating.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51571135,11274214 and 61434002the Special Funds of Shanxi Scholars Program under Grant No IRT1156+1 种基金Collaborative Innovation Center for Shanxi Advanced Permanent Materials and Technologythe Special Funds of the Ministry of Education of China under Grant No 20121404130001
文摘Magnetite (Fe3O4) nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.
文摘In order to obtain the bio-moleculel LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method.TEM analysis reveals that the monodisperse rigid sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400.Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-moleculel LDHs nanocomposites.
文摘Spherical, monodispersed europium hydroxycarbonate particles wereobtained by homogeneous precipitation with urea in aqueous solution of Eu.(NO3)3at elevated temperature.The particles were readily converted to the uniformEu2O3 with average particle size of 50nm after calcined at 750℃.
文摘The formation mechanism of monodisperse polymer latex particles in the emulsifier-free emulsion polymerizationof methyl methacrylate and butyl acrylate with potassium persulfate as initiator was investigated. A multi-step formationmechanism for the monodisperse polymer particles was proposed. The nucleation mechanism is considered to be thecoagulation of the precursor particles by homogeneous nucleation when the primary particles reach a critical size with highsurface charge density and sufficient stability. It had been proved by a special experiment that the early latex particles formedby the coagulation were stable. The primary particles grow by absorbing monomers and radicals in the polymerization systemand then become colloidally unstable again due to the understandable decrease of particle surface charge density, which leadsto the aggregation of the growing particles and the formation of larger latex pedicles therefrom. Aner the nucleation period,the preferential aggregation of the smaller particles in the propagation process leads to the change of the particles towards auniform size and narrower particle size distribution. The coexistence and competition of homogeneous nucleation,coagulation, propagation and aggregation result in the increase of the polydispersity index (U = D_(43)/D_(10)) in the first Stage,then its decrease in the later stage because of the competition of propagation and aggregation, and the gradual formation ofthe monodisperse particles.
基金the Fujian Hi-tech Project Foundation (No. 2004H008)
文摘In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS:Mn^2+ microspheres by using hydrothermal method and taking P123 surfactant as a template. The products were characterized by XRD, STEM, FT-IR and N2 adsorption-desorption. And the results show that the diameter of this microsphere is 1.0 μm or so, which is larger than that of ZnS microsphere without Mn^2+ doping, and it has monodispersion, smooth surface and uniform size, The doping of Mn^2+ does not obviously change the structure of monodispersed ZnS microsphere. The photoluminescence peak lies in a wide band ranging from 450 to 650 nm, and the microspheres emit orange light; with the increase of Mn^2+ concentration, fluorescence intensity of ZnS:Mn^2+ microsphere changes, and when the mole ratio of Mn^2+:Zn^2+ is 0.3:1, the fluorescence intensity is the strongest.