CHEMISTRY OF MATERIALS
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2017
·
IF 9.466
Changwang Zhang,Yong Xia,Zhiming Zhang,Zhen Huang,Linyuan Lian,Xiangshui Miao,Daoli Zhang,Matthew C. Beard,Jianbing Zhang
A new strategy for narrowing the size distribution of colloidal quantum dots (QDs) was developed by combining cation exchange and quantized Ostwald ripening. Medium-sized reactant CdS(e) QDs were subjected to cation exchange to form the target PbS(e) QDs, and then small reactant CdS(e) QDs were added which were converted to small PbS(e) dots via cation exchange. The small-sized ensemble of PbS(e) QDs dissolved completely rapidly and released a large amount of monomers, promoting the growth and size-focusing of the medium-sized ensemble of PbS(e) QDs. The addition of small reactant QDs can be repeated to continuously reduce the size distribution. The new method was applied to synthesize PbSe and PbS QDs with extremely narrow size distributions and as a bonus they have hybrid surface passivation. The size distribution of prepared PbSe and PbS QDs are as low as 3.6% and 4.3%, respectively, leading to hexagonal close packing in monolayer and highly ordered three-dimensional superlattice.
研究领域:
材料科学
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2016
·Vol. 8
·期 2
·55
·
IF 2.944
Baijun Liu,Yajun Wang,Mingyao Zhang,Huixuan Zhang
Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time) of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.Keywords:emulsion polymerization;particle size distribution;coagulation;initiator
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
AQUATIC TOXICOLOGY
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2025
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IF 4.3
Yao Li,Xiangrui Wang,Dingyuan Liang,Xiaoli Zhao,Zhaomin Dong,Yingchen Bai,Wen-Xiong Wang,Willie J.G.M. Peijnenburg,Ying Wang,Wenhong Fan
To assess the bioaccumulation and toxicity of nanoparticles (NPs), analyzing and modelling the relationship between the size distribution of NPs in organisms and the exposure particle size distribution represents an important challenge. Previous studies mostly focused on the NPs with single size. However, the size distribution of NPs is wide and variable in the natural environment. There is a lack of research on the NPs with mixed sizes. This study investigated the size distribution of three gold (Au) NPs with different sizes and their mixtures within a ciliate Tetrahymena thermophila under the same number concentration of particles. Results revealed that smaller particles tended to aggregate and bioaccumulate more in cells. Using expectation–maximization algorithm, a particle size distribution model of NPs in cells was established. This model effectively simulated the size distribution of NPs with mixed sizes in cells, demonstrating high accuracy with a mean absolute error of < 0.001, a root mean squared error of < 0.001, and a correlation coefficient exceeding 0.98. Experimental results further verified that the model reliably predicted the size distribution of NPs with mixed sizes in cells, and smaller particles accounted for a larger proportion of the size distribution and bioaccumulation. These results demonstrated the importance of particle size and size distribution of NPs in their environmental effects. Models developed here can provide guidance for future evaluation of the environmental risks of NPs mixtures.
研究领域:
环境科学
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毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS LETTERS
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2015
·
IF 2.489
Ming Li,Yangbowen Yang,Xiaoqing Yuan,Yongping Liu,Lingzhi Zhang
A new liquid–liquid system, employing dimethyl sulfoxide and the mixture of oleyl amine and oleic acid as separate solvents, inorganic lead salt as lead source, and sulfide as sulfur source has been developed to synthesize PbS nanoparticles with a narrow size distribution. The process can be conducted under mild conditions. The obtained PbS nanoparticles exhibit high crystallinity and uniformity. The initial Pb/S molar ratio of precursor has great effect on the particle size and optical properties of product. Larger proportion of sulfur precursor, which results in the larger particle size, is more likely to restraint crystal nucleation, rather than promote crystal growth.
研究领域:
材料科学
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化学
✓ 已验证
DOI
高影响因子
Science of Advanced Materials
·
2016
·Vol. 8
·期 6
·1200-1207
·
IF 1.812
Zhao Lili,Guo Daidong,Kang Xueliang,Liang Longyue,Yang Zhiyuan,Sang Yuanhua,Liu Hong
Barium titanate (BaTiO3) nanopowders with various morphologies and crystallinities were successfully prepared by three methods. For each of them, the sintering kinetics of the BaTiO3 ceramics tuned by morphology were correlated to exposed crystal facets, crystallinity,
interface curvature and particle size distribution. A highly crystalline particle with flat interface results in a low sintering driving force, and the grain growth proceeds along predetermined growth direction. By contrast, spherical particles with small curvature radius and low crystallinity
possess a high sintering driving force, and growth occurs rapidly in all directions. In this latter case, the resulting ceramic presents a large shrinkage and the highest rate of densification. Small particle size with homogeneous size distribution contributes to the ceramic sintering as well.
The understanding of the morphology tuned sintering kinetic of BaTiO3 ceramics provides a basis for the fabrication of BaTiO3 transparent ferroelectric ceramics in the future.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
POLYMER
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2018
·
IF 3.483
Mei Chen,Xiao Liang,Wei Hu,Lanying Zhang,Le Zhou,Cuihong Zhang,Junming Wang,Chuizhou Meng,Jingang Fang,Huai Yang
In this paper, uniform epoxy resin polymer microspheres (EMs) with controllable diameters and a narrow size distribution were prepared by precipitation polymerization using liquid crystals (LCs) as the solvent. The effects of the LC solvents on the morphologies of the resultant epoxy resin were thoroughly investigated. It was found that the formation of uniform EMs is sensitive to the properties of the LCs solvents. Uniform EMs can be obtained when the solubility parameters ( δ ) of the used solvent range from 20.59 to 21.29 (cal/cm 3 ) 1/2 and its dispersion terms ( δ d ) are in the range of 19.87–20.89 (cal/cm 3 ) 1/2 . Apart from the effects of solvents, the size of the as-made EMs can be further regulated from 2.6 μm to 10.1 μm by controlling the reactivity of epoxy monomers and the functionality of thiol hardeners. Moreover, we demonstrated that carbonizing the EMs can directly produce uniform carbon microspheres (CMs) with smooth surface. This work enlightens a new way for the preparation of EMs through precipitation polymerization in LCs solvent.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2015
·
IF 8.354
Mingxia Jiao,Jianfeng Zeng,Lihong Jing,Chunyan Liu,Mingyuan Gao
PEGylated Fe3O4 nanoparticles were prepared through flow synthesis upon the pyrolysis of ferric acetylacetonate (Fe(acac)3) in anisole at 250 °C under pressure of 33 bar, in the presence of α,ω-dicarboxyl-terminated polyethylene glycol (HOOC–PEG–COOH) and oleylamine. In combination with theoretical analysis, the effects of linear velocity, residence time, and reactor dimension on particle size distribution were systematically investigated. In addition, the impact of Ostwald ripening on particle size distribution was also revealed. In particular, the impacts of monomer concentration distributions along both axial and radial directions of the tube reactor on the particle size distribution were carefully investigated. Under optimized conditions, PEGylated Fe3O4 nanoparticles with the relative standard deviation of particle size down to 10.6% were thus obtained. The resulting 4.6 nm particles exhibited excellent colloidal stability and high longitudinal relaxivity (r1) up to 11.1 mM–1·s–1, which manifested the reliability of flow synthesis in preparing PEGylated Fe3O4 nanoparticles as contrast agents for magnetic resonance imaging applications.
研究领域:
材料科学
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医学影像
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
·
IF 4.326
Soojin Kwon,Richard Lakerveld
Emulsion solution crystallization can achieve a narrow and predictable crystal size distribution (CSD) when the emulsion droplets are uniform. The crystallization kinetics of emulsion solution crystallization are generally different from those of conventional bulk crystallization. This work characterizes the impact of temperature profile on emulsion solution cooling crystallization. The temperature is controlled by a tubular heat exchanger, and a membrane is used to create an emulsion with controllable droplet size distribution. The crystallization performance is characterized by the dynamic development of the crystal number density and the CSD, which are compared with those of bulk cooling crystallization. The crystal number density is highly sensitive to the cooling profile, and the process behavior is consistent with a system dominated by primary nucleation. Regardless of the cooling profile, secondary nucleation is suppressed in the emulsion with confined crystallization inside the droplets, which results in a narrow CSD. In contrast, secondary nucleation is dominant in bulk crystallization, leading to a broader CSD with a higher crystal number density. The mean crystal length decreases as the batch time increases with emulsion crystallization, which is different from bulk crystallization. A more predictable and narrower CSD can be obtained from emulsion crystallization, but a higher supersaturation or longer batch time is needed in emulsion crystallization to achieve a similar yield when compared to that in conventional bulk cooling crystallization.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CATALYSIS COMMUNICATIONS
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2018
·
IF 3.463
Wenhui Feng,Yuanyuan Ma,Libo Niu,Huiling Zhang,Guoyi Bai
How to control the size distribution and morphology of amorphous alloy is of vital importance in improving their catalytic performance. In this work, uniform and ultrafine NiB amorphous alloy catalysts were prepared by using a hydrogelator, 2,4-(3,4-dichlorobenzylidene)- d -sorbitol, as growth controller as well as PEG800 and tannin for co-additives, which exhibit excellent performance toward the selective hydrogenation of cinnamic acid into hydrocinnamic acid. TEM images indicated the addition of PEG800 and tannin affected the self-assembly of gelator from large aggregates into small assemblies and then affected the morphology of NiB catalysts, leading to enhancement of catalytic activity and stability.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Rui Zhao,Yuan Zong,Guang Li,Ling Zhao,Gance Dai
As emerging green solvents, ionic liquids (ILs) have promising applications in many fields. However, its long reaction time and high price restrict its industrial application. The main reason for this is due to the generation of droplets during the synthesis reaction. Aiming at the process intensification of the 1-methylimidazole (MIM)-based ILs, this paper has studied the evolution behavior of the droplets during its synthesis according to droplet breakage theory. The results show that the droplet size distribution (DSD) and its number density are closely related to the reaction progress. By comparing the Kolmogoroff microscale and droplet size, the synthesis process can be divided into Reaction stage I, when the conversion of MIM is below 60%, and Reaction stage II, when the conversion of MIM is beyond 60%. High stirring speed and temperature increase have been put forward for each stage. The reaction time can be effectively reduced by 43.93%, which is instructive in improving the production efficiency of [BMIM]Br.
研究领域:
化学工程
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Nanoscience
·
2013
·
IF 0
CHAO LIU,YANG JIANG,JIAN HUANG,HONGYAN DUAN
Lead sulfide ( PbS ) quantum dots (QDs) capped with oleic acid and oleic amine were synthesized by using safe and innocuous sulfur powder as S source instead of the bis (trimethylsilyl) sulfide ((TMS) 2 S). QDs with size distribution from 20 nm to 3 nm were gained by controlling the experiment parameters such as heating temperature, capping agents and the growth time. The morphology and crystal structure of the as-prepared PbS QDs were characterized by (high-resolution) transmission electron microscopy (HR-TEM) images and powder X-ray diffraction (XRD). This method may offer a new route to synthesize PbS QDs for photovoltaic devices.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Lu Qi,Xianghai Meng,Rui Zhang,Haiyan Liu,Chunming Xu,Zhichang Liu,Peter A.A. Klusener
Droplet size distribution (DSD) and mean droplet size of chloroaluminate ionic liquid (IL)–heptane dispersion in a stirred vessel were investigated as a model system for the composite ionic liquid/hydrocarbon system applied in the commercial isobutane alkylation process. Focused beam reflectance measurement was used to identify the phase inversion, and particle video microscope (PVM) was employed to measure the DSD of IL-continuous dispersions. The effects of agitation speed and dispersed phase holdup on the DSD and mean droplet size were investigated. Phase inversion was found at a heptane hold-up of just above 0.5. The observed DSDs could be described well by logarithmic normal distributions in spite of variable operating conditions. The DSDs appeared to be more or less independent of the dispersed phase holdup ( ϕ heptane ⩾ 0.3) at the same agitation speed. A semi-empirical correlation based on Shinnar theory was proposed to predict the droplet mean size in the impeller region for the IL-continuous dispersion, and the predicted value agreed well with the experimental data. This work will be a good basis to predict the dispersion behavior under process conditions.
研究领域:
化学工程
·
流体力学
·
多相系统
·
过程工程
·
胶体与界面科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）