氨水改性氧化石墨烯高效催化 Knoevenagel缩合反应

通过浸渍法制备了氨水改性氧化石墨烯,考察了其在苯甲醛和丙二腈的Knoevenagel缩合反应中的催化性能。通过X射线粉末衍射(XRD)、拉曼光谱(Raman)、傅里叶变换红外光谱(FTIR)、NH3程序升温脱附(NH3-TPD)、元素分析等对催化剂进行了表征,考察了工艺条件对其催化剂性能的影响。结果表明:氨水改性氧化石墨烯可以有效地将NH4+固载于氧化石墨烯表面;氧化石墨烯经氨水改性后在苯甲醛和丙二腈的Knoevenagel缩合反应中表现出良好的催化性能,随着改性实验中氨水质量分数的增加,催化剂的活性不断增加。以质量分数5%的氨水为改性剂制备的催化剂(AW-GO-5%)在60℃、4 h下催化苯甲醛和丙二腈的Knoevenagel缩合反应,苯甲醛的转化率高达93.6%,产物苄亚基丙二腈的选择性为94.8%,该催化剂重复使用4次后催化活性仍较高。     

In Situ Synthesis of Ultrahigh Molecular Weight Polyethylene/Graphene Oxide Nanocomposite Using the Immobilized Single-site Catalyst

We address the immobilization of single-site catalyst on the graphite oxide (GO) surface using methylaluminoxane. Ethylene polymerization was performed using the immobilized catalyst and the nanocomposite of ultrahigh molecular weight polyethylene (UHMWPE)/GO with less entanglement density was obtained. It was observed that the drawability, mechanical and thermal properties of the produced polymer significantly are affected by the anchoring of polymer chains to the GO nanosheets. The orientation and location of crystalline lamellae and nanosheets were verified by microscopic techniques. Besides, X-ray analysis demonstrated the dispersion of GO within the UHMWPE phase and crystallinity of UHMWPE/GO nanocomposites enhanced during drawing process.     

In Situ Processing of Graphene/Leucite Nanocomposite Through Graphene Oxide/Geopolymer

Graphene/leucite nanocomposites (rGO/leucite) were prepared through in situ reduction of graphene oxide/geopolymer (rGO/KGP) composites. The effects of rGO on the microstructure and mechanical properties with respect to the geopolymer matrix after the high‐temperature treatment were investigated systematically. The results show that GO is first partially reduced in the geopolymeric solution and then completely under the post high‐temperature treatment. The rGO sheets undergo no interfacial reactions with the matrix even after thermal treatment. The rGO/geopolymer composites fully transform to rGO/leucite composites after being treated at 1000°C for 30 min in an argon atmosphere. Significant improvements in mechanical properties were achieved through rGO reinforcement giving flexural strength, elastic modulus, and fracture toughness of 91.1 MPa, 60.5 GPa, and 2.04 MPa·m^1/2, increased by 120%, 8%, and 1.5%, respectively, compared with the leucite matrix alone.     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.     

Synthesis of Graphene Oxide/Iron Oxide/Au Nanocomposite for Quercetin Delivery

This study focused on developing a superparamagnetic graphene oxide-based nanocomposite consisting of iron oxide (IO) and gold nanoparticles for quercetin delivery. For this purpose, the structure and morphology of the designed nanocomposite (GO/IO/Au) were investigated by several characterization methods such as fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, vibrating-sample magnetometer (VSM) analysis, field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). Then, the biocompatibility of the synthesized nanocomposite was studied by Brine shrimp Artemia lethality assay, red blood cell hemolysis assay, and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Moreover, the GO/IO/Au nanocomposite efficiency as an anticancer drug delivery system was evaluated in vitro conditions. The results showed that the designed nanocomposite is highly biocompatible and possesses a favorable magnetization (M_s?=?29.2 emu.g^?1) making it a good candidate for biomedical applications. Also, it was confirmed that GO/IO/Au nanocomposite is a potent drug carrier that can effectively deliver quercetin to cancer cells.

     

氧化石墨烯/炭黑/乳聚丁苯橡胶纳米复合材料的性能研究

利用乳液插层复合法制备氧化石墨烯/乳聚丁苯橡胶（ESBR）复合胶,研究其在工程机械轮胎胎面胶中的应用。结果表明：在胎面胶中加入氧化石墨烯,氧化石墨烯/炭黑/ESBR纳米复合材料的t₉₀延长;剪切储能模量和储能模量增大,玻璃化温度变化不大,损耗因子峰值减小;主要物理性能和耐磨性能提高。     

One-Step Fabrication of Magnetic Carbon Nanocomposite as Adsorbent for Removal of Methylene Blue

Magnetic Fe₃O₄@C nanocomposites with well-defined core@shell structure were synthesized via a facile one-step solvothermal process using ferrocene as both iron and carbon resource in the presence of hydrogen peroxide (H₂O₂). The as-prepared Fe₃O₄@C nanocomposites were employed as adsorbent materials for removal of methylene blue (MB) from aqueous solution. Several experimental parameters, including contact time, acidity of the solution, and initial MB concentration were investigated. The result showed that the equilibrium uptake of MB was related to the MB initial concentration as well as acidity of the solution. The adsorption kinetics of MB was dominated by the pseudo-second order reaction model. Significantly, the synthesized Fe₃O₄@C nanocomposites could be easily isolated from the adsorption system after adsorbing MB and showed prominent reusability. All results indicated that the prepared Fe₃O₄@C composites had the potential to be used as adsorbents for the removal of dye pollutant from wastewater.     

Zinc Oxide/Graphene Oxide as a Robust Active Catalyst for Direct Oxidative Synthesis of Nitriles from Alcohols in Water

Catalysis Letters - In this work, without using any linker or chemical modification of graphene oxide, a zinc oxide immobilized graphene oxide-based catalyst was used for the direct aerobic...     

SnO2@C/还原氧化石墨烯的制备及其作为锂离子电池负极材料的性能

SnO2作为锂离子电池负极材料,因其储量丰富、放电电位低(小于1.5 V)、理论容量高等优点而被广泛研究.然而,SnO2的电导率差,且在锂离子脱嵌过程中会产生巨大的体积膨胀(300％),导致其倍率性能和循环稳定性差,限制了其实际应用.以SnCl2、L-抗坏血酸和氧化石墨烯(GO)作为反应物,采用一步水热法制备了SnO2...     

Green Catalytic Process for Click Synthesis Promoted by Copper Oxide Nanocomposite Supported on Graphene Oxide

The catalytic activity of graphene oxide supported copper oxide (CuO–GO) has been investigated in Click synthesis of 1,2,3‐triazole derivatives under green reaction conditions. In the context of green approach, water is used as solvent under ligand free and aerobic conditions at room temperature, with low catalyst loading (0.2 mol %) while ensuring the recovery and reusability of the catalyst. The catalyst affords excellent selectivity in formation of the desired products in good to excellent yields. Further, the work‐up procedure adopted here is clean and simple, while recycling the organic solvents that one used for work‐up procedure. It is proposed that the functional groups present on the GO surface are effective for preventing the aggregation of the catalytically active copper oxide species during the reaction. Moreover, the excellent performance of CuO–GO nanocomposite is ascribed to the excellent dispersity of the catalyst in water, hydrophilic nature of the GO for the accumulation of organic substrates in water and the “Breslow effect.”

     

Selective Aerobic Oxidation of Alcohols by Using Manganese Oxide Nanoparticles as an Efficient Heterogeneous Catalyst

Manganese oxide (Mn₃O₄) nanoparticles have been successfully innovated to be efficient catalysts not only for the aerobic oxidation of various alcohols to aldehydes or ketones, but also for the selective aerobic oxidation of mixed alcohols.     

氧化石墨烯的制备及其催化水解大豆异黄酮

采用改良的Hummers法制备了负载有-SO3H、-COOH和-OH的氧化石墨烯,对其进行了结构表征。并首次以氧化石墨烯为催化剂,对天然产物大豆异黄酮糖苷水解反应进行了研究。实验结果显示氧化石墨烯在异黄酮糖苷水解反应中具有较好的催化活性,其最佳反应温度为105℃,此时3种大豆异黄酮糖苷的转化率分别达到94.3%,92.1%和88.8%,苷元的收率分别达到69.6%、60.6%和58.8%。其催化活性明显优于其他固体酸催化剂,如沸石HZSM-5和大孔树脂NKA-9,而与0.02 mol.L.1的硫酸相当。     

尼龙11/石墨烯氧化物纳米复合材料的动态流变性能

采用原位聚合法制备了尼龙11(Nylon 11,Polyamide 11)/石墨烯氧化物(GO)纳米复合材料,并利用旋转流变仪研究了纳米复合材料的流变行为。研究结果表明:尼龙11及其复合材料均为假塑性流体,呈现切力变稀的现象;GO的加入降低了尼龙11/GO纳米复合材料的储能模量、损耗模量和复数黏度;用Cole-Cole理论检测尼龙11/GO纳米复合材料,其曲线出现双峰,表明复合材料发生相分离,与Han曲线一致。     

Ca-Containing Mesoporous Silica as a Solid Base Catalyst for the Knoevenagel Condensation Reaction

Abstract  

We synthesized Ca-containing FSM-16 (Ca-FSM-16) for use as a solid base catalyst for the Knoevenagel condensation reaction. Extended X-ray absorption fine structure (EXAFS) results indicated that Ca species were introduced as a calcium silicate-like phase with distorted tetrahedral coordination into the pore walls of FSM-16. Compared with conventional aminopropyl-functionalized mesoporous silica, Ca-FSM-16 showed higher activity as a solid-base catalyst for the Knoevenagel condensation reaction.     

氧化锡催化合成尼泊金戊酯

以对羟基苯甲酸和戊醇为原料,氧化锡为催化剂,甲苯为带水剂,合成了尼泊金戊酯,探讨了最佳反应条件,酯收率可达到90％,具有一定的应用价值。