Journal of the Korean Ceramic Society
·
2023
·Vol. 60
·期 5
·830-839
·
IF 2.5
Li Xiaohong,Luo Xiaoyu,Li Jing,Li Jinxia,Yang Jiahao,Ahmad Zahoor,Bao Zhihao,Zhang Xiao,Chen Jianjun
An appropriate infusible method plays a vital role as one of the key processes of the fabrication of polymer-derived ceramic fibers. In this work, ozone curing, a novel room temperature controllable curing strategy was used to prepare SiCN ceramic fibers. Some circular pores were observed on the surface of the obtained SiCN ceramic fibers. The tensile strength of the fibers was also investigated. To reveal the ozone-curing mechanisms of the PSZ fibers and the formation process of the circular pores, the FT-IR, SEM, OM, XRD and TG were characterized. The results showed that the Si–H bonds and Si-CH 3 groups in the PSZ molecule were oxidized gradually to form oxygen-containing groups such as Si–OH, Si–O-Si and C = O in the ozone curing process, which contributed to the curing and weight gain of the PSZ fibers. Moreover, a hydrolysis reaction between Si-NH-Si and H 2 O might further accelerate the curing of the PSZ fibers. An unexpected result of the hydrolysis reaction is the formation of some circular pores on the surface layer of the PSZ fibers. This strategy provides a method to design, adjust and control the microstructure and composition of silicon-based ceramic fibers, and the obtained SiCN fibers may be used as catalyst support, bacterial culture and other fields.
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Wei Wang,Le Pang,Ming Jiang,Yaping Zhu,Fan Wang,Jingwen Sun,Huimin Qi
In this study, we investigated the tunable porous structure of SiCN(O)-derived ceramic aerogels by changing the molecular structure of the polysilazanes from linear to branched. We also studied the effect of molecular structure on the thermal insulation properties of ceramic aerogels. As the percentage of branched molecular structure in the polysilazane precursor increased, the internal microscopic pore structure of the aerogels changed from macroporous to mesoporous. The specific surface areas and pore volumes of the ceramic aerogels prepared with different precursors increased after pyrolysis at 1000 °C, ranging from 3.7 to 255.9 m 2 /g and 0.01–0.36 cm 3 /g, respectively. The corresponding thermal conductivities increased slightly as the aerogels contracted after pyrolysis. The low thermal conductivity (0.046 W/(m·K) at minimum) can be attributed to the decrease in pore size caused by adjusting the precursor structure, which limits the thermal conduction of gas in the porous aerogel materials.
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2023
·
IF 8.8
Jingna Cui,Yimu Wei,Jiangong Jiang,Shouchun Xiao,Xueke Liu,Zhiqiang Zhou,Donghui Liu,Peng Wang
The bioaccumulation, metabolism, tissue-specific distribution and toxicity of the widely used organophosphorous pesticide malathion to zebrafish were investigated on an enantiomeric level for evaluating the environmental risks. The metabolites were also monitored and evaluated. Malathion was metabolized by zebrafish very fast with the half-life of 0.12 d and showed a middle accumulation capacity in zebrafish with bioaccumulation factor (BCF) of 12.9 after a 15-d exposure. Brain could enrich higher concentration of malathion than other tissues. The metabolites malaoxon, malathion/malaoxon monocarboxylic acid (DMA), malathion/malaoxon dicarboxylic acid (DCA), dimethylthiophosphate (DMTP) and dimethyldithiophosphate (DMDTP) were found, in which DMTP and DCA were in higher level, indicating the metabolism was mainly induced by carboxylesterase degradation. The accumulation of malathion and malaoxon was stereoselective in zebrafish tissues, exhibiting S-enantiomer preferentially enriched. The acute toxicity test showed rac-malathion was low toxic to zebrafish, which was 1.2 and 1.6 folds more toxic than S-malathion and R-malathion respectively. Malaoxon was highly toxic to zebrafish and approximately 32 times more toxic than malathion. The toxicity of other metabolites was lower than malathion. Malathion could cause an apparent developmental toxicity to zebrafish embryo, including bradycardia, hatchability reduction and deformity, and abnormal movement patterns in zebrafish larva. Chronic toxicity indicated that malathion and malaoxon induced oxidative damage and neurotoxicity in the liver, brain and gill of zebrafish, and malaoxon exhibited a relatively high injury to the zebrafish brain. The results can provide information for the comprehensive assessment of the potential risk of malathion to aquatic organisms and highlight the necessity of consideration of stereoselectivity and metabolites when systemically evaluating pesticides.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 12
·2094
·
IF 5.719
Hongming Liu,Qin Zhou,Yongfu Lian
Individual single–walled carbon nanotubes (SWNTs) with distinct electronic types are crucial for the fabrication of SWNTs–based electronic and magnetic devices. Herein, the water–soluble polymethyl(1–butyric acidyl)silane (BA–PMS) was synthesized via the hydrosilylation reaction between 3–butenoic acid and polymethylsilane catalyzed by 2,2′–azodibutyronitrile. As a new dispersant, BA–PMS displayed a quite good dispersing capacity to arc–discharged SWNTs and moderate selectivity for metallic species. The application of sucrose–DGU, the density gradient ultracentrifugation with sucrose as the gradient medium, to the co–surfactants (BA–PMS and sodium dodecyl sulfonate) individually dispersed SWNTs yielded metallic SWNTs of 85.6% purity and semiconducting SWNTs of 99% purity, respectively. This work paves a path to the DGU separation of the SWNTs dispersed by polymer–based dispersants with hydrophobic alkyl chains.Keywords:polymethyl(1–butyric acidyl)silane;dispersion;density gradient ultracentrifugation
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 137
·期 44
·49376
·
IF 2.52
Zhaoqi Niu,Dan Tian,Long Yan,Xiaoyan Ma,Chengshuang Zhang,Xiao Hou
3,13-Diglycidyloxypropyloctaphenyl double-decker silsesquioxane (EP-DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction of methyldichlorosilane, followed by hydrosilylation with allyl glycidyl ether, and the resultant structure was confirmed by fourier transform infrared spectrometer (FTIR) and nuclear magnetic resonance (NMR), respectively. The thermosetting phenol-formaldehyde (PF) resin was then modified by EP-DDSQ, and the reactivity of PF resin with EP-DDSQ and thermal pyrolysis of modified cured resin were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface morphologies of modified resins at high temperature were characterized with field emission scanning electron microscope (FESEM), and chemical structure of modified resins was analyzed through X-ray photoelectron spectrometer (XPS). The results showed that the appropriate addition of EP-DDSQ did not affect the curing temperature of the PF resin itself, but could improve the heat resistance of the system. When the amount of EP-DDSQ added was 10%, the initial degradation temperature of PF resin was increased by 49.31°C, and when the amount of EP-DDSQ added was 16%, the char yield of which was reached up to 61.39%, compared with that of pure PF resin (TGA 1,000°C of 57.62%) at Ar atmosphere. More importantly, the modified resin formed a regular and dense layer of SiC and SiO x ceramic on the surface after ablation in the muffle furnace at 800°C air atmosphere, which is very important for ablative resistant materials.
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2019
·Vol. 16
·期 6
·2173-2180
·
IF 1.074
Ming-Ye Yang,Bin-Bin Dong,Fei-Hong Wang,Xin Xu,Simeon Agathopoulos
This paper reports on the successful fabrication of α -Si 3 N 4 -nanowire/Y 2 Si 2 O 7 composite membranes with superhydrophobic properties, aiming to achieve a high performance in membrane distillation. The starting powder mixture of 87 wt% γ -Y 2 Si 2 O 7 , 5 wt% Si, 3 wt% LiYO 2 , and 5 wt% ferrocene catalyst was dispersed in a stable suspension, and after being tape-casted, it was sintered at 1300°C for 4 hours in order to obtain the composite membrane. α -Si 3 N 4 nanowires with a diameter of about 50 nm were formed, distributed uniformly on the surface and in the pores of the membrane and their presence greatly favored superhydrophobicity. After surface modification with a robust hydrophobic layer of SiNCO nanoparticles, strongly adhered to the surface of the produced membrane, a water contact angle of 153 o , was measured. Water desalination experiments, using a sweeping gas membrane distillation (SGMD) device, were conducted. High water flux of 11.91 L/m 2 /h was achieved for a 4 wt% NaCl feeding solution at 90°C. Stable water flux and rejection rates were recorded in long-term experiments (>500 hours) using the produced superhydrophobic composite membrane.
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Yongzhao Hou,Bo Xiao,Zhiyuan Sun,Wen Yang,Songsong Wu,Shuai Qi,Guangwu Wen,Xiaoxiao Huang
With the rapid development of high power electromagnetic (EM) equipment and high-speed aircraft, the powerful and high oxidation-resistance absorbers are fundamentally desirable for the EM field. Herein, a novel high temperature anti-oxidative SiC/Fe 3 Si/CNTs composite is synthesized by a facile polymer derived ceramic (PDC) route from a Fe-containing polysilyacetylene (PSA). The microstructure of as-prepared SiC/Fe 3 Si/CNTs composite absorber is featured by micro-sized SiC ceramic grains with spherical Fe 3 Si nanoparticles and carbon nanotubes (CNTs) attached to. The vector network analyzer tests show a tunable wave-absorbing performance by adjusting the thickness of layer, and the effective bandwidth (the reflection loss < −10 dB) is 3.3–16.8 GHz for the sample S-1400 (heat treatment at 1400 °C in nitrogen flow). The minimal RL value is −41.2 dB at 10.5 GHz at a thickness of 2 mm and an effective bandwidth is nearly 4 GHz (12.9–16.9 GHz) at the thickness of only 1.5 mm. Moreover, after the oxidation treatment at 800 °C in the air, this absorber maintains the main structure and shows a good high temperature oxidation resistance . This absorber still remains excellent wave absorption property, in view of a minimal RL value of −40 dB at the thickness of 3 mm and a bandwidth of 4.8 GHz (10.4–15.2 GHz) at the thickness of 2.5 mm. The mechanism of high EM wave absorption performance is studied and attributed to the impendence matching, polarization, and the magnetic properties . Thus, the SiC/Fe 3 Si/CNTs composite is a promising EM absorber for high-temperature EM wave-absorbing applications.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2018
·
IF 3.794
Ming-Ye Yang,Jun-Wei Wang,Lin Li,Bin-Bin Dong,Xu Xin,Simeon Agathopoulos
This paper reports on the successful fabrication of γ-Y 2 Si 2 O 7 membranes with low thermal conductivity , which is an important membrane property for achieving high performance in membrane distillation process. Single-phase γ-Y 2 Si 2 O 7 powder was first synthesized by calcination of SiO 2 and Y 2 O 3 powders, with 3 wt% LiYO 2 as a sintering aid. The membrane was produced by tape-casting of a suspension of this powder. After sintering at 1300 °C for 4 h, a flat membrane was obtained, which had a thickness of 0.5 mm, 49% porosity, 0.9 μm pore diameter, and low thermal conductivity of 0.497 W/m⋅K at 32 °C, and 0.528 W/m⋅K at 100 °C. The obtained membrane presented hydrophobic features (water contact angle was 132°) after surface modification, which resulted in formation of a strongly adhered robust hydrophobic SiNCO nanoparticle layer on its surface. The resultant hydrophobic membrane was tested in water desalination experiments using a sweeping gas membrane distillation (SGMD) device. High water flux of 10.07 L⋅ m −2 ⋅ h −1 was achieved for a 20 wt% NaCl feeding solution and a temperature at the feed of 90 °C. Stable water flux and rejection rates were recorded in long-term experiments (>400 h).
✓ 已验证
产品关联
DOI
高影响因子
FIRE AND MATERIALS
·
2019
·Vol. 43
·期 6
·685-693
·
IF 1.173
Wenpeng Song,Wang Zhang,Yonggang Li,Huijuan Ma,Tao Lin,Cuifen Lu,Junqi Nie,Guichun Yang,Zuxing Chen
Summary Two kinds of novel silicon-phosphorus linear polymers were synthesized by the hydrosilylation reaction of double-decker-shaped silsesquioxane (DDSQ) and 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) derivatives and characterized using 1 H NMR, 31 P NMR, and 29 Si NMR. Flame-retardant polycarbonate/acrylonitric-butadiene-styrene (PC/ABS) blends were prepared with different contents of silicon-phosphorus linear polymers. The flame-retardant properties of silicon-phosphorus linear polymers as well as the morphology were investigated in detail by using thermogravimetric analysis (TGA), limiting oxygen index (LOI), (Underwriters Laboratory) UL-94, microscale combustion calorimetry (MCC), and scanning electron microscopy (SEM), respectively. The silicon-phosphorus linear polymers containing DDSQ and DOPO units can synergistically improve the flame retardancy and thermal stability of PC/ABS blends. Flame-retardant polymers with different linkers between DDSQ and phosphate units show comparable effect on the flame retardancy of PC/ABS.
✓ 已验证
产品关联
DOI
高影响因子
POLYMER INTERNATIONAL
·
2014
·Vol. 63
·期 10
·1875-1880
·
IF 2.247
Chunfang Li,Zhupeng Zhang,Jinrong Wu,Dongxiang Li,Wanguo Hou
Dendritic amphiphiles as novel building blocks are very important for self-assembling in the supramolecular chemistry area. In this work, a carbosilane dendrimer with hexamethylene as the branching unit (G1) was first synthesized as a hydrophobic core and then linked with poly(ethylene glycol) (PEG) units as the periphery by a hydrosilylation reaction to prepare an amphiphilic dendrimer (G1-PEG) with a yield of 27%. The aggregation behavior of G1-PEG in water was studied with surface tension, dynamic light scattering and transmission electron microscopy methods. The surface tension data showed that the critical aggregation concentration of such dendrimers in water is approximately 0.75 g L −1 . The results of dynamic light scattering and transmission electron microscopy indicated that the aggregate size of G1-PEG dendrimers in water is related to the concentration. Small micelles of about 10 nm were found at high concentration, large vesicles of about 100 nm were observed at low concentration, and a mixture of micelles and vesicles was found at middle concentrations. The encapsulation of G1-PEG to a fluorescence probe verified the existence of a hydrophobic microenvironment in the aggregates at high concentrations of the amphiphilic dendrimer. © 2014 Society of Chemical Industry
✓ 已验证
产品关联
DOI
高影响因子
FIBERS AND POLYMERS
·
2015
·Vol. 16
·期 10
·2094-2105
·
IF 0.881
Cai Lu,Li Zhanxiong
Three novel fluoroalkylsilyl polymethacrylates, namely mono(fluoroalkyl)silyl polymethacrylate (PMFSA), bis(fluoroalkyl)silyl polymethacrylate (PBFSA) and tris(fluoroalkyl)silyl polymethacrylate (PTFSA), were synthesized via emulsion polymerization in this study. Subsequently, those fluoroalkylsilyl polymethacrylates were applied onto the surface of cotton fabric to make the fabric water-repellent. Particle size, zeta potential and transmission electron microscopy (TEM) were employed to analyze the emulsion stability and particle morphology. The surface properties of the coated cotton fabrics were confirmed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Thermal properties of fluoroalkylsilyl polymethacrylates and coated cotton fabrics were evaluated by thermal gravity analysis (TGA). Contact angle measurement (CA) demonstrated that the incorporation of more fluorinated segments into the fluoroalkylsilyl methacrylate comonomer molecule and increasing fluorine content can improve the water repellency of treated cotton fabrics. In addition, the fabric’s washing durability was found to be prominent. Even after 15 household machine washes, the water contact angles could be maintained as 132.7 °, 133.9 ° and 128.9 °, respectively.
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Jiuduo Xu,Weihai Zhang,Qiyang Jiang,Jianxin Mu,Zhenhua Jiang
A series of novel copoly(aryl ether sulfone)s with polydimethyl (PDMS) and double-decker-shaped silsesquioxane (DDSQ) in the main chain were synthesized by nucleophilic substitution polymerization approach. Dihydroxy terminated eugenosiloxanes (2OH-PDMS-n) and 3,13-di(2-methoxy-4-propylphenol)octaphenyl DDSQ (2OH-DDSQ) were synthesized. These two difunctional oligomers were used to copolymerize with 4-fluorophenyl sulfone to obtain poly(aryl ether sulfone) containing cage and linear organosiloxane (Si-PES) through one-step high-temperature solution method. Si-PES with multiple PDMS and DDSQ contents in the main chains were obtained by adjusting the molecular weight of 2OH-PDMS-n and controlling the molar ratio of 2OH-DDSQ to 2OH-PDMS-n. The dielectric constants sharply decreased as organosiloxane was introduced compared with traditional PES which the lowest value was achieved at 5% DDSQSi–PES (2.36 at 1 MHz). In addition, enhanced hydrophobic capacity peaks were obtained at 50% DDSQSi-PES surface hydrophobicity (113°) as the synergies of both linear organosiloxane and DDSQ. Furthermore, thermal and crystallization behaviors , as well as surface properties, were investigated.
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）