JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2019
·Vol. 91
·期 1
·44-53
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IF 1.986
Cai Huafei,Jiang Yonggang,Li Liangjun,Feng Junzong,Feng Jian
Abstract Monodispersed silica sol with a small particle size, narrow size distribution, and high conversion was prepared via a modified Stöber method, and an orthogonal test method was used to investigate the influence of TEOS concentration, R (H 2 O/TEOS), ammonia concentration, and reaction temperature on the particle size, size distribution, and conversion of silica sol. It was found that the remarkable factors affecting the particle size from a large to a small order were ammonia concentration, reaction, temperature, and R (H 2 O/TEOS) value; similarly, the remarkable factors affecting the silica sol conversion from a large to a small order were the R (H 2 O/TEOS) value and reaction temperature in decreasing order of influence. None of the factors investigated in this study exhibited a significant effect on the particle size distribution. The optimal synthesis conditions for the preparation of monodispersed silica sol with small particle size and high conversion were as follows: TEOS concentration = 0.4 mol/L; R (H 2 O/TEOS) = 60; ammonia concentration = 0.10 mol/L; reaction temperature = 75 °C. The average particle size of monodispersed silica sol under optimum conditions was 5.25 ± 0.77 nm, and the conversion was 94.05%. Besides, this study also provides a systematic experimental and theoretical basis for the preparation of different particle sizes monodispersed silica sol with high conversion.
Monodispersed silica sol with small particle size, narrow size distribution and high conversion was prepared via a modified Stöber method, and orthogonal test method was used to investigate the influence of TEOS concentration, R (H 2 O/TEOS), ammonia concentration and reaction temperature on the particle size, size distribution and conversion of silica sol. Under the optimum conditions, the monodispersed silica sol with 5.27 ± 0.82 nm average particle size and 94.05% conversion rate was obtained.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Journal of Energy Storage
·
2025
·
IF 9.8
Huichao Liu,Liping Feng,Sheng Zhu,Yunzhen Chang,Yanping Li,Wenjing Hou,Yun Zhao,Liangti Qu,Gaoyi Han
Engineering porous carbon with small mesopores and narrow pore distribution is an effective strategy to trade-off the capacitive performances and pore structure of carbon materials. Here, mesoporous carbon with small pore size and bimodal distribution is successfully constructed from the mixture of coal tar pitch and agar via one-pot pyrolysis method in molten salt (KCl/KHCO 3 ). The formation process of bimodal pore structure is unveiled. During pyrolysis process, the agar with rich oxygen-containing groups generates abundant free radicals, which can not only accelerate the cross-linking reaction rate of pitch molecules to construct the carbon sketch, but also introduce oxygen-containing functional groups between carbon layers to effectively prevent the stacking effect of carbon. Therefore, the diffusion of molten KCl/K 2 CO 3 into the interior of the carbon layer is facilitated to achieve homogeneous activation to form bimodal pore structure. In three-electrode testing system, the optimized carbon shows superior rate capability with a specific capacitance of 220.0 F g −1 at 200.0 A g −1 in 6.0 mol L −1 KOH electrolyte. In two-electrode system, the capacitors in 1.0 mol L −1 TEABF 4 /acetonitrile achieves maximal energy density of 44.6 Wh kg −1 and power density of 34,000 W kg −1 . This work supplies a facile strategy to prepare small-sized mesoporous carbon material with high capacitive performances.
研究领域:
材料科学
·
电化学
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产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Qiang Zhang,Xu Li,Jinxiang Dong
Despite significant breakthroughs that have been made in the application performance of traditionally distributed Guerbet alcohol ethoxylates (GAEO), research on the characteristics of their narrow distribution products remains relatively limited. Herein, a series of hydrophilic and hydrophobic nonionic surfactants have been synthesized via the ethoxylation of 2-butyl-octanol with ethylene oxide. Ca(OAc) 2 was employed as a narrow distribution (NRD) catalyst, while KOH served as a broad distribution (BRD) catalyst. The synthesized products were characterized using Fourier-transform infrared (FT-IR), 1 H and 13 C nuclear magnetic resonance ( 1 H, 13 C NMR) spectroscopy. In addition, a comprehensive assessment of the physicochemical and surface properties of the NRD GAEO surfactants was conducted through systematic investigations. The results were then compared to conventionally distributed GAEO surfactants. The study has demonstrated that NRD GAEO surfactants exhibited lower critical micelle concentration (CMC) values, which have the higher efficiency of the surfactant application. In addition, the NRD products have superior wettability performance, reduced foaming capacity in foam properties, and improved rapid defoaming capacities. In regarding their other properties, they closely mirrored the performance of BRD products. These findings will contribute to a comprehensive understanding of the properties of NRD ethoxylates and have substantial practical implications in optimizing personal care and household cleaning products.
研究领域:
化学
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材料科学
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表面活性剂技术
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产品关联
DOI
高影响因子
Journal of Materials Chemistry B
·
2012
·Vol. 1
·期 2
·204-212
·
IF 0
Youshen Wu,Yan Li,Lei Qin,Feilong Yang,Daocheng Wu
A two-step organic sol–gel process for the preparation of monodispersed or narrow-dispersed melamine–formaldehyde (MF) resin polymer colloidal spheres in water was developed. A modified Stöber process was used to coat the MF colloidal spheres with silica shells, which rendered the surfaces of these colloidal spheres easily modifiable. The prepared MF@silica core–shell composite colloidal spheres were then bioconjugated with bovine serum albumin to demonstrate the feasibility of using these colloidal particles as supporting materials in bioassays. The particle formation mechanism of this organic sol–gel process was investigated by time-resolved microscopic analysis. The prepared MF nano-/microscale resin polymer spheres were monodispersed or narrow-dispersed with a controllable average size ranging from 30 nm to 250 nm and from 0.8 μm to 4.5 μm. The spheres were stable in aqueous or organic solvents and after heat treatment above 300 °C. A “controlled aggregation” model was proposed to explain the influences of the key factors in this process.
研究领域:
材料科学
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化学
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纳米技术
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生物化学
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产品关联
DOI
PubMed
MACROMOLECULES
·
2018
·
IF 5.914
Congguang Zheng,Yan Zhou,Yanpeng Jiao,Huiqi Zhang
Controlled preparation of narrow or monodisperse, physically cross-linked, and “living” spherical polymer particles by one-stage reversible addition–fragmentation chain transfer (RAFT) precipitation polymerization (RAFTPP) is described for the first time. The introduction of RAFT polymerization mechanism into precipitation polymerization system, together with the use of methacrylic acid (MAA) (capable of forming hydrogen bonding) as the monomer, allows ready generation of uniform spherical poly(MAA) (PMAA) particles with surface-bound “living” dithioester groups, easily tunable sizes, and low molecular weights in the absence of any cross-linking monomer. The polymerization parameters (i.e., monomer loading, molar ratio of the RAFT agent to free radical initiator, and polymerization temperature) showed much influence on the morphologies and yields of PMAA particles, and their simple adjustment allows fine-tuning of “living” PMAA particle sizes. The presence of dithioester groups on such PMAA particles was confirmed not only by their light pink color and characteristic UV–vis absorbance peak of dithioester units but also by their capability of directly grafting cross-linked apolar polymer shells. Some uniform “living” PMAA-based functional copolymer microspheres were also prepared in a one-stage process by simply incorporating glycidyl methacrylate, 2-hydroxyethyl methacrylate, or a fluorescent monomer into the RAFTPP of MAA, demonstrating the high versatility and general applicability of the RAFTPP system. The polymerization of MAA in RAFTPP proved to occur both in the continuous phase and on PMAA particle surfaces instead of inside particles, and a combined “grafting from” and “grafting to” particle growth mechanism is proposed for RAFTPP.
研究领域:
高分子化学
·
材料科学
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大分子化学
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胶体与界面科学
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化学合成
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）