不同形貌/晶型CdSe纳米材料的合成

以乙二胺(en)为溶剂, 通过调控反应物中镉源与硒源的摩尔比得到了不同形貌与晶型的CdSe纳米材料, 达到了同时调控形貌与晶型的目的. 当反应物中镉源与硒源摩尔比为1∶1时, 得到的产物为en体系常见的六方相棒状CdSe纳米晶体；当反应物中镉源与硒源摩尔比为1∶2时, 得到的产物为立方相CdSe纳米颗粒. 进一步研究结果表明, 反应体系中Se^2－离子生成的多少及速度是影响反应进程得到不同产物的关键.     

不同形貌/晶型CdSe纳米材料的合成

以乙二胺(en)为溶剂, 通过调控反应物中镉源与硒源的摩尔比得到了不同形貌与晶型的CdSe纳米材料, 达到了同时调控形貌与晶型的目的. 当反应物中镉源与硒源摩尔比为1∶1时, 得到的产物为en体系常见的六方相棒状CdSe纳米晶体；当反应物中镉源与硒源摩尔比为1∶2时, 得到的产物为立方相CdSe纳米颗粒. 进一步研究结果表明, 反应体系中Se^2－离子生成的多少及速度是影响反应进程得到不同产物的关键.     

溶剂热法合成蜂巢状氧化镍及其电化学电容性能

利用N，N-二甲基甲酰胺(DMF)为溶剂的溶剂热法制备了蜂巢状氧化镍，反应过程中DMF既做溶剂又做沉淀剂。研究了不同制备条件对NiO形貌及电化学性质的影响，并用X-射线衍射(XRD)、扫描电子显微镜(SEM)以及循环伏安(CV)技术进行了表征。结果表明，300 ℃热处理得到的氧化镍，10 mA电流下单电极比电容达460 F·g^-1。     

氢氧化镍微米棒的合成和表征

以NiCl₂为镍源,乙二醇(EG)为溶剂,采用溶剂热法成功地制备了β-Ni(OH)₂微米棒,制备方法简单、易行。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、傅立叶红外光谱(FTIR)和电感耦合等离子直读光谱仪(ICP)对产物的形貌和物质结构进行了表征,证实了反应中间体是Ni-EG配合物。利用扫描电子显微镜(SEM)考察了实验参数,如聚乙二醇200浓度、反应温度和反应时间,对产物形貌的影响,结果表明一维棒状β-Ni(OH)₂的形成经历了溶解-再结晶的过程。Ni-EG配合物经退火处理,可以得到由纳米线自组装的NiO微米管。     

液相热分解纳米铁镍合金的形貌可控合成及其磁学性能研究

以Fe(CO)₅和Ni(HCOO)₂为前驱物,十八烯为溶剂,在表面活性剂和分散剂油酸和油胺的协同作用下,通过前驱体的液相热分解和自合金化,制备铁镍合金纳米颗粒。通过XRD和TEM研究了产物的微观结构,并对产物的磁学性质进行了表征。结果表明,在反应温度为200 ℃,油胺与油酸及甲酸镍的物质的量比为4∶2∶1,反应时间为20 min时可得形貌可控、抗氧化性强的面心立方晶体结构的平面三角形纳米铁镍合金,晶粒尺寸为15~55 nm。磁性测量表明,300 K时三角形形貌铁镍合金的饱和磁化强度为15.5 emu·g^-1,矫顽力趋近于零,呈现超顺磁性;在低温(4.2 K)时,铁镍合金的饱和磁化强度为17.5 emu·g^-1,矫顽力增大明显。     

球形微米镍颗粒的液相体系制备及应用

本研究采用液相还原法,选用六水合硫酸镍为镍源,水合肼为还原剂,在封端剂聚乙烯吡咯烷酮的辅助下,制备得到球形微米镍颗粒。所制备的球形微米镍颗粒粒径约为3 μm,粒径分布均匀,表面粗糙度较低。为了获得球形微米镍颗粒的最优工艺方案,分别探究了PVP浓度、氢氧化钠和水合肼用量及反应温度等工艺参数对产物形貌的影响。研究发现,PVP能够有效控制镍原子的排布和沉积,NaOH可调节反应的pH值,确保水合肼持续还原Ni₂₊^,温度会影响体系的还原反应速率。结果表明：当反应体系使用的PVP浓度为0.5 M、NaOH用量为2.5 mL、水合肼用量为5 mL时,在 60 ℃下水浴反应可获得表面粗糙度低的球形微米镍颗粒,其电导率为5×10₅ S.m_-1^,饱和磁化强度为49.34 emu.g_-1^{。通过添加去离子水、异丙醇和羧甲基纤维素的混合溶液},将球形微米镍颗粒配制成25 wt%的导电油墨,并在纸基表面绘制导电线路,经测试该线路的电导率为1.28×10₃ ^S.m_-1^,此电路在弯折条件下,呈现出良好的工作稳定性。     

镍/碳纳米纤维复合物的制备及其吸波性能

以乙二胺为碳源,自制的镍纤维为催化剂,利用原位复合的方法制备得到一系列不同比例的镍/碳纤维复合物,并研究了其吸波性能.由于镍纤维和碳纤维均具有一定的电磁波耗散能力,因此得到的产物无需任何处理,可以直接作为吸波材料使用.结果表明,通过改变镍纤维的加入量,可以改变产物的镍碳比,进而实现对复合材料吸波性能的调控.在合适比例条件下制备得到的纤维复合物具有较好的吸波性能,当纤维复合物含量为25%时,其反射率的最小值可达-14.3dB.该材料在轻质吸波材料领域具有很好的应用价值.     

熔融盐法制备LiMn2O4材料的合成条件研究

采用熔融盐法制备锂离子电池正极材料LiMn₂O₄,对制备过程中熔融盐种类、焙烧时间和焙烧温度等影响因素进行了系统研究。通过XRD、SEM和充放电测试,研究了产物的组成结构、形貌及电化学性能。研究结果表明,合成的LiMn₂O₄样品具有完整的尖晶石结构;样品的粒径分布范围小,平均粒径为几百纳米;优化实验条件之后制备得到的材料,在电压范围3.3～4.3 V,充放电电流值为60 mA·g^-1(0.5C)时     

不同晶型和形貌MnO2纳米材料的可控制备

以KMnO4为锰源, 采用水热技术在180 ℃条件下于不同种类酸溶液中可控制备了α-, β-, δ-MnO2, 系统研究了 K＋, H＋及阴离子对制备产物MnO2晶型和形貌的影响. 研究结果表明, K＋与H＋在反应体系中对于制备产物晶相的生成形成竞争性影响, 其量的大小对制备产物晶型具有控制作用, 高浓度K＋离子有助于生成α-MnO2, 而高浓度的H＋有利于生成β-MnO2; 阴离子的种类和浓度对制备产物MnO2的晶型和形貌无显著影响. 在对制备产物进行XRD, SEM和元素分析的基础上, 提出了不同晶型和形貌MnO2的可能形成机理.     

形貌可控ZnO微纳米结构的水热合成及光催化性能

以乙醇胺为辅助溶剂,采用水热合成法,制备了花状、梭状和剑状的ZnO微纳米结构。采用扫描电镜（SEM）、Ｘ射线衍射（XRD）、光致发光光谱（PL）和拉曼光谱等测试手段对样品的形貌、结构、晶相等进行了表征。结果表明所有样品均为六方纤锌矿结构ZnO;其形貌和结晶度可通过改变物质的量的配比n_Zn²⁺/n_OH^-来调控。探讨了反应物配比对产物形貌结构的影响,乙醇胺对不同形貌ZnO的制备起到至关重要作用。以亚甲基蓝为目标降解物,采用紫外-可见吸收光谱（UV-Vis）并结合低温氮吸附-脱附比表面测试（BET）,研究了花状、梭状和剑状ZnO的光催化活性。结果表明,与商用ZnO相比,制备的ZnO具有更好的光催化活性;样品催化活性与其比表面积不成正比,具有最小比表面积的花状ZnO拥有最好的光催化活性,这可能是由于其低的结晶度和特殊的花状形貌所致。     

Study on correlation of morphology of electrospun products of polyacrylamide with ultrahigh molecular weight

Polyacrylamide (PAAm) with ultrahigh molecular weight of 9 × 10⁶ g/mol has been processed by means of electrospinning, to afford products with a variety of morphologies, including polymer colloids, beaded fibers, smooth fibers, and ribbons. These morphologies can be controlled by a minute change of solution concentration in a small concentration range (0.3–3.0 wt %), because of the high molecular weight of the polymer. Under our experimental conditions, no electrospun product was obtained at the concentrations below 0.3 wt %. Beaded fibers and smooth fibers formed at the concentrations between 0.3 and 0.7 wt %. At concentrations between 0.7 and 2.0 wt %, smooth fibers and ribbons coexisted. At concentrations above 2.0 wt %, ribbons were the only product. Special morphologies such as triangular beads, helical fibers, and zigzag ribbons were also observed. With a lower molecular weight PAAm, branched fibers were found in the product. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2190–2195, 2005     

CoMnO2-Decorated Polyimide-Based Carbon Fiber Electrodes for Wire-Type Asymmetric Supercapacitor Applications

In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO₂-coated and Fe₂O₃-coated carbon fibers were used as the cathode and the anode materials, respectively. Herein, the nanostructured CoMnO₂ were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatment in presence of ammonium persulfate (APS) as an oxidizing agent. FE-SEM analysis confirmed that the CoMnO₂-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amount of APS, and Fe₂O₃-coated carbon fiber electrode showed a uniform distribution of porous Fe₂O₃ nanorods over the surface of carbon fibers. The electrochemical properties of the CoMnO₂-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g⁻¹ at 0.7 A g⁻¹ and good rate capability of 34.8% at 4.9 A g⁻¹. Moreover, the wire-type device displayed the superior energy density of 60.2 Wh kg⁻¹ at a power density of 490 W kg⁻¹ and excellent capacitance retention of 95% up to 3000 charge/discharge cycles.     

Morphology‐Controlled Self‐Assembly of an Organic/Inorganic Hybrid Porphyrin Derivative Containing Polyhedral Oligomeric Silsesquioxane (POSS)

An organic/inorganic hybrid porphyrin derivative, namely, metal‐free tetrakisphenyl porphyrin–polyhedral oligomeric silsesquioxanes (H₂TPP‐POSS) was synthesized by azide–alkyne click chemistry. The self‐assembly behavior of H₂TPP‐POSS was systematically studied in CHCl₃ at different concentrations and in solvents with different polarities. Novel nanovesicles could be obtained through the self‐assembly of H₂TPP‐POSS in CHCl₃ at a concentration lower than 10^?4 m. Diffuse microrods formed at a concentration higher than 10^?4 M . Additionally, the polarity of the solvent also greatly influenced the assembled morphologies, and a series of assembled morphologies, including crescent‐shaped micelles, spherical micelles, doughnut‐shaped vesicles, and ordered square sheets, could form in solvents with different polarities.     

Thermodynamic modeling and investigation of the formation of electrospun collagen fibers

Electrospun type I collagen fibers are very promising materials for tissue scaffold applications, but are typically fabricated from toxic solvents. Recently, electrospinning of type I collagen fibers by using environmentally friendly phosphate buffer saline (PBS)/ethanol solution has been explored. PBS/ethanol solvent systems offer better cell compatibility, but the high surface tension and high boiling point of the solvent system make the collagen difficult to electrospin and can cause inferior fiber morphology. In this study, the influence of solvent surface tension on the morphology of electrospun collagen fibers has been experimentally investigated and analyzed from a thermodynamics perspective. The analytical results indicate that solvents with high surface tension drive the formation of beads along the smaller, thinner fibers. In addition, beads with relatively small angular eccentricity were thermodynamically favorable. The experimental results presented herein corroborate the theoretical analysis and conclusions drawn from this study. The surface tension of the solvent has significant influence on the bead formation, especially in an aqueous system. The environmental humidity for the electrospinning process and the collagen concentration were also investigated. These parameters may result in variations of the evaporation-solidification rates, which consequently impact the formation and morphologies of electrospun collagen fibers. According to the thermodynamic analysis, uniform electrospun collagen fibers without beads can be obtained by manipulating solvent surface tension during the electrospinning process.     

Highly Ordered Nanoporous Films from Supramolecular Diblock Copolymers with Hydrogen‐Bonding Junctions

We designed efficient precursors that combine complementary associative groups with exceptional binding affinities and thiocarbonylthio moieties enabling precise RAFT polymerization. Well defined PS and PMMA supramolecular polymers with molecular weights up to 30 kg mol^?1 are synthesized and shown to form highly stable supramolecular diblock copolymers (BCPs) when mixed, in non‐polar solvents or in the bulk. Hierarchical self‐assembly of such supramolecular BCPs by thermal annealing affords morphologies with excellent lateral order, comparable to features expected from covalent diblock copolymer analogues. Simple washing of the resulting materials with protic solvents disrupts the supramolecular association and selectively dissolves one polymer, affording a straightforward process for preparing well‐ordered nanoporous materials without resorting to crosslinking or invasive chemical degradations.     

Wet-spun porous fibers from high internal phase emulsions: Continuous preparation and high stretchability

Although high internal phase emulsion (HIPE)-templating is promising to prepare macroporous materials (polyHIPEs) with controllable shapes and tuneable property, fibrous polyHIPEs with stretchability and their continuous preparation are still challenging. Here, we report the fabrication of polyHIPE fibers in a continuous manner through wet spinning of HIPEs. The successful fabrication of polyHIPE fibers depends on HIPE dispersed phase fractions, ammonia-catalyzed interfacial reaction and wet spinning. Dry polyHIPE fibers exhibit tunable diameters, hierarchically porous structures, high stability to temperature and to various solutions, and high stretchability (with a high tensile strain of 155%), which is hard to achieve for polyHIPEs. The polyHIPE fibers show enhanced uptakes to both water (14.4 ml g⁻¹) and organic solvents (up to 26.3 ml g⁻¹), and the amphiphilic swelling is rare for polyHIPEs. Moreover, the dry polyHIPE fibers show good thermal insulation, similar to that of cotton. Simple wet spinning, combining with HIPEs with tuneable composition, is promising for preparing various polyHIPE fibers for various potential applications.     

Helical stacking tuned by alkoxy side chains in pi-conjugated triphenylbenzene discotic derivatives

We report on the synthesis and self-assembly of a new series of discotic molecules containing triphenylbenzene as the core and alkoxy side chain with varying length. It was found that compounds 3 a-c, 4 b and 5 b could form stable gels in several apolar solvents. Transmission electron microscopy (TEM) images revealed that their morphologies were very different for the different alkoxy-substituted organogels. In toluene or hexane, 3 b and 3 c resulted in both left- and right-handed helical fibers, whereas 3 a resulted in straight rigid fibers; 4 b and 5 b resulted in most straight fibers with a few twisted fibers. The results from FT-IR and UV/Vis absorption spectroscopy indicated that the hydrogen bonding and pi-pi interactions were the main driving forces for the formation of the self-assembled gels. Further detailed analysis of their aggregation modes were conducted by UV-visible absorption spectra and X-ray diffraction (XRD) measurements. Based on these findings, the influence of these peripheral alkoxy substituents on the gel formation and the aggregation mode were discussed. The special enhanced fluorescent emissions, which resulted from aggregation, were also found in the gel phase.     

Spectroscopic studies on some complexes of nickel(II) and palladium(II) with thiosemicarbazides

Summary The electronic absorption spectra of the complexes M(L)Cl₂ and M(L)₂Cl₂ [M=Ni^II or Pd^II; L=thiosemicarbazide (tsc), 1-phenylthiosemicarbazide (1-phtsc), or 4-phenylthiosemicarbazide (4-phtsc)] were investigated in a number of solvents. The complexes Ni(tsc)Cl₂, Ni(tsc)₂Cl₂, Ni(4-phtsc)Cl₂ and Ni(4-phtsc)₂Cl₂ exist in a distorted O_h geometry when dissolved in any of the solvents used. On the other hand, the complex Ni(1-phtsc)₂Cl₂, although weakly paramagnetic, proved to be planar. Theoretical and experimental results proved that the complex has neither O_h nor T_d geometry. Molecular orbital calculations were performed on some selected complex ions assuming a local point group symmetry of D_2h.     

n‐Channel Organic Transistors Processed from Halogen‐Free Solvents: Solvent Effect on Thin‐Film Morphology and Charge Transport

Non‐chlorinated solvents are highly preferable for organic electronic processing due to their environmentally friendly characteristics. Four different halogen‐free solvents, tetrafuran, toluene, meta‐xylene and 1,2,4‐trimethylbenzene, were selected to fabricate n‐channel organic thin film transistors (OTFTs) based on 3‐hexylundecyl substituted naphthalene diimides fused with (1,3‐dithiol‐2‐ylidene)malononitrile groups (NDI3HU‐DTYM2). The OTFTs based on NDI3HU‐DTYM2 showed electron mobility of up to 1.37 cm²·V^?1·s^?1 under ambient condition. This is among the highest device performance for n‐channel OTFTs processed from halogen‐free solvents. The different thin‐film morphologies, from featureless low crystalline morphology to well‐aligned nanofibres, have a great effect on the device performance. These results might shed some light on solvent selection and the resulting solution process for organic electronic devices.     

Novel CuS nanofibers using organogel as a template: controlled by binding sites

A new cholesterol organogelator 1 was synthesized, which was confirmed as an effective gelator for various organic solvents and could self-assemble into network fibers in some organic solvents. Moreover, gelator 1 could act as templates for the synthesis of various CuS nanofibers with different helical pitches. For example, when H(2)S was used as the sulfur source, straight and bending helical CuS nanofibers with a pitch of 100-200 nm could be fabricated in butyl acetate and benzene-butanol gel systems, respectively, while bending CuS nanofibers with a similar helical pitch (ca. 50 nm) could be obtained when thioacetamide was used as the sulfur source in both gel systems. It was first found that the morphologies of inorganic nanofibers could be controlled by the binding sites between the inorganic precursor and the organogel.