RSC Advances
·
2013
·Vol. 4
·期 1
·510-515
·
IF 2.562
Huan Wang,Baoqing Shentu,Zhixue Weng
A one-pot synthetic approach for the preparation of poly(2,6-dimethyl-1,4-phenylene oxide)/polystyrene (PPO/PS) alloy in aqueous medium was developed. The method was based on the combination of the oxidative coupling polymerization of 2,6-dimethylphenol (DMP) to form PPO in the presence of a reactive swelling agent, styrene (St), and in situ reverse atom transfer radical polymerization (RATRP) of St initiated by 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIBI) in alkaline aqueous solution. The complex of CuCl2 and 4-dimethylaminopyridine (DMAP) was utilized as the catalyst to catalyze the two types of polymerization mentioned above. Oxygen was employed as the sole oxidant to synthesize PPO. The introduction of St during the oxidative polymerization of DMP could increase the molecular weight of PPO. Finally thermodynamically compatible PPO/PS alloy was successfully prepared.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
POLYMER
·
2024
·
IF 4.1
Hongjing Pei,Yanmei Han,Yong Liu,Xu Han
Although copper-aliphatic amines have been extensively used as catalysts for the polymerization of 2,6-dimethylphenol (DMP) to poly (2,6-dimethyl-1,4-phenylene oxide) (PPO), the high polydispersity index (PDI) of PPO and high content of 3,3′,5,5′-tetramethyl-4,4'diphenoquinone (DPQ) in PPO significantly affect the physical properties of PPO . In this study, different CuBr-aromatic amines have been used as catalysts for synthesizing PPO. CuBr– N -methylbenzylamine shows a high yield of PPO (94.4 %) with the low DPQ yield (0.46 %) and PDI (1.33) in the presence of 0.1 % H 2 O, which facilitates the formation of dinuclear Cu(Ⅱ) species. In addition, the low dielectric constants (2.43 and 2.25) and low dielectric loss factors (1.07 × 10 −3 and 1.29 × 10 −3 ) of the PPO synthesized by CuBr– N -methylbenzylamine and CuBr-4-aminopyridine again indicate that aromatic amines are more appropriate for the synthesis of PPO with superior dielectric properties . Meanwhile, the high-molecular-weight PPO can be successfully redistributed to low-molecular-weight PPO by adding DMP in the presence of CuBr– N -methylbenzylamine, and the decreased T g values from 212.5 to 187.8 °C with decreasing M n values from 2.7 × 10 4 to 5.5 × 10 3 indicate the improved processability of the low-molecular-weight PPO. This study provides new insights on important roles of aromatic amines in the synthesis of PPO.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2014
·Vol. 2
·期 43
·18562-18573
·
IF 0
Lijia Yang,Beibei Tang,Peiyi Wu
In this work, graphene oxide (GO) was first functionalized with branched polyethyleneimine (PEI). The obtained PEI–GO was incorporated into a brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) matrix by a covalent bond interaction to form a cross-linking network. Then, a novel ultrafiltration (UF) membrane was prepared via casting and phase-inversion methods. The PEI–GO/BPPO membrane showed highly improved water flux, which was almost 6 times higher than that of the pristine BPPO membrane and 2.5 times higher than that of the GO/BPPO membrane, whereas the rejection of PEI–GO/BPPO membrane was still maintained at a high level. The improvement of membrane performance could be attributed to the special property of PEI–GO and the interactions between PEI–GO and the BPPO matrix. First, a cross-linking network of PEI–GO/BPPO membrane was formed because of the reaction between PEI–GO and the BPPO matrix to provide passageways for water rapidly passing through. Second, the high hydrophilicity of PEI–GO could accelerate the exchange rate between solvent and non-solvent, resulting in a rougher and more hydrophilic surface, higher porosity and a more porous structure. Third, the good dispersion and compatibility of PEI–GO promoted the formation of a uniform structure with fewer defects. Proper molecular weight of PEI was very important for the modification of GO, subsequently resulting in an overall enhancement in membrane performance. Anti-fouling experiments and stability tests of the membranes were also conducted. All of these results were confirmed by various characterizations, such as SEM, TEM, AFM and, etc.
研究领域:
材料科学
·
环境工程
✓ 已验证
DOI
POLYMER
·
2025
·
IF 4.5
Ya-Qi Wang,Qing He,Zhi-Yang Zhang,Lei Zhang,Na-Juan Yuan,Yong Liu,Hai-Tao Ren,Xu Han
Although the low molecular weight poly(2,6-dimethyl-1,4-phenyl oxide) (LMW-PPO) has been extensively applied in the field of 5G communication, the complicated procedures involved in the synthesis of LMW-PPO and efficient recovery of the homogeneous catalysts are still challenging nowadays. In this study, five ionic liquids (ILs) have been successfully synthesized, and LWM-PPO is directly synthesized using different Cu(OAc) 2 -ILs complexes as catalysts. Among them, Cu(OAc) 2 - IL(a) not only exhibits the high yield of LWM-PPO (83.68%, M n =3.6✕10 3 ) with the low 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ) yield (0.12%) and polydispersity index (PDI, 1.39) in methanol, but also maintains high stability after being recycled for 5 times. In addition, with increasing H 2 O contents in the system from 1.0% to 5.0%, the M n values of PPO decrease from 2.9✕10 3 to 2.4✕10 3 with the narrow PDI values in the range of 1.22-1.45, indicating that trace H 2 O effectively promotes the formation of binuclear Cu(II) complex between Cu(OAc) 2 ·H 2 O and ILs, which then polymerizes 2,6-dimethylphenol (DMP) to LMW-PPO. The synthesized LMW-PPO exhibits high thermostability ( T d5% =427.07-430.52°C), low glass transition temperature ( T g =167.6-180.3°C), and low dielectric constant ( D k =2.14-2.64, 1 GHz) and dielectric loss ( D f =2.83✕10 -3 -4.91✕10 -3 , 1 GHZ), indicating that it is more appropriate to be used in the field of 5G communication. This study provides new insight on the importance of ILs in direct synthesis of LMW-PPO with high performances.
研究领域:
材料科学
·
化学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Huimin Ruan,Shangshang Gao,Yeyang Li,Shuaijun Yu,Junbin Liao,Edison Huixiang Ang,Yanqing Xu,Jiangnan Shen
Proton blocking anion exchange membranes (AEMs), which are employed in electrodialysis technology, show promise in acid recovery from industrial waste. A series of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) membranes were prepared using (3-aminopropyl)trimethoxysilane (APTMS) and weakly functionalized bases including N-butylimidazole (N-BuIm). Were networked to create AEMs with low leak rates. It was discovered that the appropriate concentration of siloxane crosslinker raised the membrane matrix's density and lowered the AEM matrix's hydrophilicity. Thermogravimetric measurements and water absorption have confirmed this, and the membranes in this series even swell up to 8.61 %. The maximum H + concentration concentrated by the cross-linked AEM (BPPO/5Si) during the ED with a current density of 10 mA ∙ cm −2 was 2.35 M, which was higher than the concentration concentrated by the uncross-linked AEM (BPPO/OSi), which was 1.90 M (beginning concentration: 1.00 M). The current efficiency was 44.8 % and the energy consumption was only 1.81 kW ∙h∙kg − 1 . A balance between proton blocking and SO 4 2− ions transport was achieved by the optimized AEM, which exhibited increased hydrophobicity and smaller ion clusters. The improved AEM was found to have fewer ionic clusters and greater hydrophobicity. For cross-linked AEMs, a trade-off between SO 4 2− ions transport and proton blocking was thus accomplished. This work is thought to offer direction for developing sophisticated proton blocking AEMs.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2019
·
IF 2.298
Daixiang Wei,Lingqi Kong,Xinshun Tan,Shiqing Zheng
The binary vapor–liquid equilibrium (VLE) data at the pressure of 101.3 kPa, which are 3,3-dimethyloxetane + methyl cyclohexane and 3-chloro-2,2-dimethyl-1-propanol + methyl cyclohexane, have been measured using a modified Rose vapor-recirculating equilibrium still. The reliability of VLE data was verified by thermodynamic consistency of area test of Herington and point test of Van Ness. The experimental data were regressed with activity coefficient models of Wilson, nonrandom two-liquid, and UNIQUAC, respectively, and the corresponding binary interaction parameters were obtained using the maximum likelihood method. The root-mean square deviations between calculated and experimental data for the vapor phase molar fraction and equilibrium temperature were less than 0.0119 and 0.58 K, which indicated that the fitted results for the three models were within acceptable limits.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 70
·66215-66223
·
IF 3.289
Fa-Shuo Shan,Jia-Ping Lai,Hui Sun,Ping Zhang,Chong Luo,Yan-Hui He,Huan-Ran Feng
A fast responsive and highly selective mercury(II) sensor was developed using the fluorescence quenching mechanism of 2,9-dimethyl-1,10-phenanthroline (2,9-DMP) towards mercury(II). Furthermore, two kinds of metal–organic frameworks (MOFs) of 2,9-DMP–Hg(II) have been synthesized and characterized by X-ray diffraction. The probe 2,9-DMP exhibited a fast and highly selective response to mercury(II) ions in aqueous solution, showing a good linear relationship over the concentration range of 0.050–2.0 μM for Hg(II) with R2 = 0.9994. The established procedure was used to monitor the concentration of mercury(II) in drinking water and Zhujiang River water samples with satisfactory recoveries of 85.42–101.5% and 81.72–96.09%, respectively. Furthermore, the fluorescence quenching mechanism of 2,9-DMP by mercury(II) was investigated and clarified by the data of single crystal X-ray diffraction of MOFs and the Job's plot analyses of 2,9-DMP towards Hg(II).
研究领域:
分析化学
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2024
·
IF 6.1
Lu Yan,Yue Shen,Zidan Zou,Xiao Zhang,Zhixin Yu,Guozhong Wang,Chun Chen
Hydrogenation of aromatic rings can be used not only for synthesis fine chemicals, but also for hydrogen storage and transportation using organic hydride. In this paper, yolk-shell structural SiO2@Ru@NC catalyst, which was successfully synthesized by a strategy of combining modified Stöber and vacuum-assisted impregnation, revealed excellent catalytic activity in dimethyl terephthalate (DMT) hydrogenation to dimethyl 1,4-cyclohexanedicarboxylate (DMCD), which is a green chemical reagent and precursor for high-value chemicals. Characterization results showed that highly dispersed Ru NPs with subnanometer size distribution were encapsulated in yolk-shell nanoarchitecture and the mesoporous shell could ensure unhindered diffusion of reactant molecules. Moreover, yolk-shell structure-induced interaction of Ru and carbon shell allowed for tuning electronic structure of Ru species, which in turn could regulate catalytic properties. The yolk-shell nanoarchitecture catalyst offers advantages of low active metal loading, excellent activity and stability, thus can expand application of ultra-low loaded precious metal catalysts in catalytic conversion of aromatic compounds.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Russian Journal of Physical Chemistry A
·
2025
·Vol. 98
·期 13
·3009-3016
·
IF 0.8
Zhe Wang,Li Junzhi,Zhao Wei,Li Xiao Liang
The isobaric vapor-liquid equilibrium data for the four systems consisting of 1-octene + 2-methyl-thiophene, cyclohexene + 2-methylthiophene, 2,3-dimethyl-1-butene + 2-methylthiophene, and 2,3-dimethyl-2-butene + 2-methylthiophene were determined by using a modified Rose-Williams equilibrium still at 90.00 kPa. All the vapor-liquid equilibrium data measurements passed the thermodynamic consistent test by employing the Herington method. The azeotropic behavior was observed in the 1-octene + 2-methyl-thiophene system. Additionally, the experimental data were correlated by the Wilson model, and they were also compared with the original UNIFAC and UNIFAC Dortmund predictive models. All the results indicated that the measured data were in good agreement with the calculated values obtained from the Wilson. Meanwhile, the UNIFAC Dortmund model can provide better prediction result than the original UNIFAC model.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2018
·Vol. 165
·期 5
·F350
·
IF 3.662
Yunfei Yang,Yixin Xu,Niya Ye,Dengji Zhang,Jingshuai Yang,Ronghuan He
Quaternization of poly(2,6-dimethyl-1,4-phenylene oxide)s (PPOs) with a series of saturated heterocyclic compounds was carried out via the Mannich reaction to fabricate anion exchange membranes (AEMs) with high alkaline chemical stability and ion conductivity. The heterocyclic quaternary ammonium cations include 1-methylpyrrolidinium (MPy), 1-ethylpyrrolidinium (EPy), 1-butylpyrrolidinium (BPy), 1-methylpiperidinium (MPrD), 1-ethylpiperidinium (EPrD) and N-methylmorpholinium (NMM). For comparison, trimethylammonium (TMA) and 1-methylimidazolium (MeIm) functionalized PPO membranes were fabricated as well. The physicochemical properties of the prepared membranes were investigated in terms of water uptake, swelling, ion exchange capacity, mechanical properties, conductivity and tolerance to alkalies. The AEMs having saturated heterocyclic quaternary ammonium groups exhibited better resistance to nucleopholic attack of hydroxide ions than PPO-TMA and PPO-MeIm membranes, especially the PPO-MPy membrane, which retained its initial conductivity of 87.5% after immersed in 1M KOH at 80°C for 508 h.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2013
·
IF 2.206
Yijian Wu,Lei Gui,Huan Wang,Baoqing Shentu,Zhixue Weng
A novel and convenient synthetic method for the preparation of α,ω-bis(2,6-dimethylphenol)-poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-2OH) oligomer in water is presented. It is based on the oxidative copolymerization of 2,6-dimethylphenol (DMP) and aromatic diols in the presence of Cu-ethylene diamine tetraacetic acid catalyst in water. It was found that the mole fraction of PPO-2OH in the product was affected by species of aromatic diols and mole ratio of DMP to aromatic diols. Species and concentration of surfactants were demonstrated to be significant factors that would influence molecular weight (Mn) and yield of PPO-2OH. The synthesized PPO-2OH was end-group modified with methacryloylchloride (MAC) to obtain dimethacryloyl chloride telechelic PPO (PPO-2MAC). The relationship between glass transition temperature (Tg) and Mn of PPO-2OH is in good agreement with the Flory–Fox equation. Thermal polymerized low-molecular-weight PPO-2MAC has a constant Tg at about 208 °C.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2025
·
IF 4.9
Qian Li,Liang Gao,Hao Zou,Yibin Luo,Xingtian Shu,Hao Wang
The dehydration-Prins condensation of tert‑butanol (TBA) and paraformaldehyde to produce 4,4-dimethyl-1,3-dioxane (DMD) was investigated using Hβ zeolites with a controlled Si/Al ratio. The acidic properties, including type, strength, and density, were systematically characterized, revealing that both total acid density and weak Brønsted acid density critically govern DMD selectivity. Specifically, reducing the weak Brønsted acid density from 204.91 to 92.94 μmol/g resulted in an 18 % decrease in DMD selectivity. Reaction pathway analysis identified the dehydration of TBA to isobutene as the key initial step. Furthermore, the introduction of extra-framework aluminum species enhanced the Lewis acid density and the Brønsted-to-Lewis (B/L) acid ratio. TBA dehydration experiments confirmed that Lewis acids originating from extra-framework aluminum significantly promote this critical step. Under the optimized conditions of 125 °C, 3.0 MPa, 0.417 mol of paraformaldehyde, 0.208 mol of TBA, 20 wt % H 2 O, and 1.7 wt % Hβ22, the conversion of TBA reached 59.1 %, the selectivity for DMD was 57.3 %, and the main by-product was identified as an over-condensation product with a 1,3-dioxane structure.
研究领域:
催化化学
·
有机化学
·
物理化学
·
材料科学
·
化学反应工程
✓ 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）