空心ZnMn2O4纳米球和纳米立方体的室温合成及氧还原催化性能

室温条件下,在含有Zn2+的溶液中,以空心结构的MnO2作为前驱体,使用NaBH4作为还原剂,合成了尖晶石型的ZnMn2O4纳米空心球和纳米空心立方体. 通过XRD,SEM,TEM,BET等测试手段对合成产物的结构、形貌、组成、表面性质进行了表征. 实验结果表明,所制备的空心结构ZnMn2O4纳米球和纳米立方体的尺寸在400?600 nm, 空心结构的壳层是由5?6 nm颗粒紧密堆积而形成,厚度约为40 nm. 将所制备的纳米ZnMn2O4空心结构应用于氧还原（ORR）反应中,研究了其在碱性溶液中的氧还原电催化性能,结果显示,相对于ZnMn2O4纳米空心立方体,ZnMn2O4纳米空心球在氧还原反应中表现出较大的电流密度和高的电子转移数 (n=3.5), 具有较好的氧还原电催化性能,有望成为一种新型的氧还原电极电催化剂.     

锂离子电池负极材料ZnMn2O4微米空心球的制备和电化学性能

通过溶剂热方法合成了ZnMn2O4微米空心球,并探讨了其形成机理。采用XRD,SEM,TEM等测试手段对产物的结构、形貌和组成进行了表征。实验结果表明,溶剂热反应条件如反应温度、反应介质对于产物的结构和形貌起着关键作用。在140℃,采用乙醇和水作为反应介质,反应6 h可以制备出直径约3μm的ZnMn2O4微米空心球;当以乙醇为溶剂,反应6 h可以得到团聚的尺寸约250 nm的ZnMn2O4纳米颗粒。将所制备的ZnMn2O4微米空心球/纳米颗粒组装成锂扣式模拟电池,考察其电化学脱嵌锂性能。电化学测试结果显示,与ZnMn2O4纳米颗粒相比,空心结构的ZnMn2O4微米球具有较高的初始放电容量(1335 mAh·g-1)和较好的倍率性能,有望作为锂离子电池的新型负极材料。     

核壳结构Ni0.5Zn0.5Fe2O4/PANI复合纳米材料的制备及表征

采用微乳液法制备出Ni0.5Zn0.5 Fe2O4纳米颗粒以及Ni0.5Zn0.5Fe2O4/PANI核壳结构复合纳米材料,借助FT-IR、XRD、SEM、TEM、VSM等分析手段研究了材料的形貌、结构与磁性能.结果表明:得到的Ni0.5Zn0.5Fe2O4纳米颗粒平均粒径为20hm左右,Ni0.5Zn0.5 Fe2O...     

HgI2-HI-H2O溶液中静电场诱导的α-碘化汞晶体生长

在HgI_2-HI-H_2O溶液体系中,采用静电场诱导技术生长了HgI_2晶体。利用紫外-可见光谱分析了溶液中分子/离子的存在形式;通过改变电场强度和溶液浓度等因素,得到了不同形貌的HgI_2晶体。结果表明,HgI_2-HI-H_2O溶液中存在[HgI_3]~-,[HgI_4]~(2-)和HgI_2等3种主要成分。静电场诱导离子发生定向迁移,形成取向性生长的晶体,晶体形貌受电场诱导和结构因素(分子键力)共同制约。溶质(负离子)向正极迁移,形成颗粒度大的HgI_2晶体;负极主要是由中性HgI_2键合并相变形成的小颗粒HgI_2晶体。分析认为,HgI_2-HI-H_2O溶液中负离子可以成为晶体生长的基本单元。     

喷雾热解法制备球形SrAl_2O_4:Eu,Dy长余辉发光材料

采用喷雾热解两段法制备了SrAl2O4:Eu,Dy长余辉发光材料,利用SEM、荧光长余辉亮度测试、F-4500荧光分光光度等方法分析了不同制备工艺条件下SrAl2O4:Eu,Dy发光材料的形貌、余辉性能以及光谱性能的变化。采用喷雾热解两段法可制备出余辉性能良好的球形SrAl2O4:Eu,Dy长余辉发光材料。前驱体溶液浓度、热解温度、添加剂对产物的形貌、粒度分布、发光性能有较大影响。较之高温固相法,喷雾热解法制备的SrAl2O4:Eu,Dy具有合成温度低、发光性能好、形貌好、粒度分布窄等优点。     

Zn_2GeO_4纳米棒的制备及发光性质

采用水热合成法制备了纯菱形相的Zn_2GeO_4纳米棒,研究了水热制备前驱体溶液的pH值对材料尺寸及形貌的影响以及Zn_2GeO_4纳米棒的光学性质。扫描电子显微镜(SEM)测试结果表明,随着前驱体溶液pH值的变化样品逐渐由微米级块状结构生长成为纳米颗粒,并且进一步形成纳米棒结构。纳米棒的尺寸由长200 nm变化到500 nm。室温光致发光(PL)光谱中观察到位于450和530 nm两个不同的发光峰,其分别源于Zn_2GeO_4的不同缺陷能级。     

pH值对Bi_2MoO_6晶体形貌和可见光催化性能的影响

以(NH4)6Mo7O24·4H2O和Bi(NO3)3·5H2O为原料,采用普通水热法制备Bi2Mo O6光催化剂,研究p H值对制备该光催化剂的影响。对所制备的系列样品,采用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积分析仪、X射线光电子能谱仪(XPS)和紫外-可见漫反射(UV-Vis DRS)进行表征。结果表明:p H值对Bi2Mo O6晶体的物相组成、形貌和光催化性能均有显著影响。p H值为1~7时,所制备的样品为纯相Bi2Mo O6,p H值为9或11时,出现第二相Bi3.64Mo0.36O6.55;随着p H值的升高,形貌依次为纳米棒、纳米片和无规则纳米颗粒。在可见光(λ≥420 nm)照射下,通过光催化降解罗丹明B(Rhodamine B,Rh B),探讨了制备Bi2Mo O6的p H值对其可见光催化活性的影响。当p H=7时,制备的样品光催化效果最好,光照50 min后对初始浓度为5 mg·L-1的罗丹明B溶液的降解率为85%。     

C_3N_4/BiVO_4/Cu_2O复合材料用于纯水中CO_2光还原为甲醇

采用分步合成方法将Cu_2O纳米颗粒原位还原组装到C_3N_4/BiVO_4表面,设计并合成了C_3N_4/BiVO_4/Cu_2O复合材料.在该过程中,首先将具有光氧化能力的BiVO_4与C_3N_4复合制备出C_3N_4/BiVO_4复合物,进一步通过原位合成法在C_3N_4/BiVO_4复合物表面沉积Cu_2O纳米颗粒制备出C_3N_4/BiVO_4/Cu_2O复合材料.通过高分辨透射电镜和高分辨扫描电镜,X射线粉末衍射,紫外-可见光谱及荧光光谱等测试方法对材料的结构、形貌与组成进行了系统的表征.在纯水体系中,光催化研究表明该复合材料具有较好的二氧化碳到甲醇的转化效率,复合材料的形成有利于促进光生电子和空穴的分离,从而提高光催化性能.     

刻蚀剂对IrO_2-MnO_2阳极纳米涂层表面形貌及电化学行为的影响

采用传统热分解法制得了不同刻蚀剂(HCl、H2SO4、C2H2O4和HF)处理的Ti基Ir O2-Mn O2纳米涂层阳极,使用场发射扫描电子显微镜(FESEM)、循环伏安(CV)及极化技术等观察和研究各纳米涂层阳极表面形貌及其电化学性能.结果表明,与HCl和C2H2O4刻蚀剂相比,HF和H2SO4刻蚀的基底涂层表面Ir O2纳米颗粒更为密集且尺寸更大;H2SO4刻蚀处理的Ti基Ir O2-Mn O2阳极电催化活性最佳,HF次之,C2H2O4再次之,HCl最差.     

EDTA辅助水热法合成硫化铋晶体

以Bi(NO3)3·5H2O和Na2S2O3·5H2O为原料,用乙二胺四乙酸(EDTA)辅助水热法合成了纳米或微米级的Bi2S3晶体(1),其结构、形貌和光谱性能经XRD,FE-SEM和UV-Vis表征。结果表明:溶液的pH对1的形貌有显著的影响,随着pH的增大,1由纳米棒组成的微米球逐渐转变为微米级片状结构;1出现蓝移。     

嵌段液晶高聚物对聚醚砜 - 聚对苯二甲酸乙二醇酯/聚对羟基苯甲酸共混物的增容作用

嵌段液晶高聚物对聚醚砜 聚对苯二甲酸乙二醇酯／聚对羟基苯甲酸共混物的增容作用张海良张雪飞王霞瑜（湘潭大学化学化工学院湘潭４１１１０５）关键词增容作用，嵌段共聚物，原位复合材料基于热致性液晶高分子（ＴＬＣＰ）的原位复合材料以其高性能及易加工等特点而得...     

Structure,properties and interfacial interactions in poly(lactic acid)/polyurethane blends prepared by reactive processing

Polyurethane elastomers are promising candidates for the impact modification of PLA producing blends for example for biomedicine. Poly(lactic acid) (PLA)/polyurethane elastomer (PU) blends were prepared by reactive processing and physical blending as comparison. The blends were characterized by a number of techniques including microscopy (scanning electron microscopy, SEM, and atomic force microscopy, AFM), rotational viscometry, thermal (dynamic mechanical analysis, DMA), and mechanical (tensile) measurements. The analysis and comparison of the structure and properties of physical and reactor blends proved the successful coupling of the phases. Coupling resulted in more advantageous structure and superior mechanical properties compared to those of physical blends as confirmed by morphology, macroscopic properties and the quantitative estimation of interfacial interactions. Structural studies and the composition dependence of properties indicated the formation of a submicron, phase-in-phase structure which positively influenced properties at large PU contents. The results strongly support that reactive processing is a convenient, cost-effective and environmentally friendly technique to obtain blends with superior properties.     

Polymer single crystals of poly(4-hydroxybenzoate). I. Morphology

Poly(4-hydroxybenzoate) was prepared from 4-acetoxybenzoic acid, 4-pivaloyloxybenzoic acid, and 4-trimethylsiloxy benzoyl chloride by condensation without the addition of a catalyst. Although various reaction conditions were used the products were always crystalline. The morphology of the as-polymerized crystals has been studied by transmission electron microscopy as a function of molecular weight and end-group type. It was possible to detect morphological features during the course of reaction from oligomers to polymer which enabled us to determine the mechanisms that are likely to control chain growth for different regimes of polymerization kinetics.     

Copolymer with long chain alkyl group as stabilizer in the preparation of biodegradable polyester particle

Poly(eicosyl methacrylate‐co‐2‐hydroxyethyl methacrylate) is synthesized by free radical polymerization of eicosyl methacrylate and 2‐hydroxyethyl methacrylate by using 2,2′‐azobisisobutyronitrile as initiator in N,N‐dimethylformamide at 80°C. Copolymers of different molecular weights are synthesized and well characterized by different analytical techniques and used as a stabilizer in the preparation of polycaprolactone and polylactic acid particles by solvent evaporation method. The formation of the polymer particles and its morphology with respect to the stabilizer molecular weights, concentration, and reaction time are studied. Well dispersed poly(caprolactone) and poly(lactic acid) particles are formed, which demonstrated the efficiency of the copolymeric stabilizer. Polymer particle sizes and its stability depend on the molecular weights and concentration of the stabilizer. The surface morphology and particle sizes of the prepared particles are characterized by field emission scanning electron microscope.     

聚天冬氨酸的合成研究

以L-天冬氨酸为原料,磷酸为催化剂,在不同溶剂中进行缩聚反应,合成中间体聚丁二酰亚胺(PSI),当混合溶剂为m三甲苯／m环丁砜=7／3时,可得到较高分子量的PSI。当催化剂与单体的质量比为0．14时,分子量达到最大值。将PSI碱解得到聚天冬氨酸。     

PLGA/明胶共混体系的静电纺丝研究

采用静电纺丝技术制备了聚乳酸乙醇酸(PLGA)/明胶(Gt)的复合超细纤维, 考察了溶液浓度、电压及流速对纤维形貌的影响. 研究了不同明胶比例的纤维膜的微观形貌和干湿态的力学性能. 结果表明, 在溶液浓度0.12 g/mL, 电压7.5 kV, 流速0.8 mL/h条件下, 所得PLGA/Gt复合纤维直径较小, 粗细较均匀且缺陷少. 含有明胶的复合纤维直径远小于PLGA单纺纤维直径, 明胶的加入降低了膜的拉伸强度和断裂伸长率, 提高了膜的亲水性. 经PBS浸泡后, 复合膜的弹性得到加强. 明胶质量分数为5%和10%时, 纤维直径分布较窄, 当明胶的质量分数增加至15%时, 纤维的直径分布变宽.     

葡萄糖敏感微凝胶的溶胀动力学研究

通过沉淀聚合法合成了P(NIPAM-co-AA)微凝胶,然后在EDC催化下用3-氨基苯硼酸对微凝胶进行改性,制备了P(NIPAMI-co-AAPBA)微凝胶.红外光谱检测证明改性完全.改性后的微凝胶仍具有很好的温敏性,但由于引入疏水的苯硼酸基团,微凝胶的体积相转变温度大大降低.P(NIPAM-co-AAPBA)微凝胶具...     

Effect of Molecular Weight on the Properties of Poly（butylene succinate）

Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.     

Microfiltration membranes with pH dependent property prepared from poly(methacrylic acid) grafted polyethersulfone powder

Poly(methacrylic acid) (PMAA) grafted polyethersulfone (PES) powder was prepared by γ-ray irradiation-induced graft polymerization. The existing of the PMAA side chains in the grafted powder was proved by FT-IR spectroscopy. Then, pH dependent microfiltration (MF) membranes were cast from PES-g-PMAA powder with different degree of grafting (DG) under phase inversion method. The contact angle, mean pore size and swelling behavior of MF membranes were measured. The morphology was studied and the water filtration property was also tested. The results showed that the mean pore sizes and filtration properties of MF membranes cast from PES-g-PMAA powder varied with pH. In the most variant case, the flux of acid solution was about four times as that of basic solution for the MF membrane cast from PES-g-PMAA with DG of 20.0%.     

Poly(3,5‐dichloroaniline) Doped with Different Sulfonic Acids

Poly(3,5‐dichloroaniline) was prepared by chemical oxidation in the presence of various sulfonic acids as doping agent, using potassium permanganate as oxidant. 1‐Naphtalene sulfonic acid, 2‐naphatalene sulphonic acid, 1,5‐naphtalene disulfonic acid, and p‐toluenesulfonic acid were the acids of choice. Infrared and UV‐Vis spectroscopy, utilized to characterize the polymers, revealed that the compounds exist in the emeraldine (conductive) oxidation state. The level of doping, conductivity, and morphology were determined as well. The presence of a sulfonic acid produces a morphological change, from granular to microtubule structures, which is responsible for the strong increase in the conductivity of the polymer.