纳米银形状控制合成与聚合物纳米银复合材料

纳米银(Ag NPs)由于其独特的物理、化学和生物学特性备受研究人员的关注.纳米银应用性能除了受到粒子尺寸、分布、纯度等因素影响,还与纳米银的形状密切相关.纳米银的形状对纳米银的抗菌性能、光学性能以及聚合物纳米银复合材料的综合性能都会产生重要影响.纳米银的形状控制合成可以进一步发挥聚合物纳米银复合材料的性能潜力.因此,不断发展纳米银新的合成方法,研究纳米银形状控制的机理就显得尤为重要.本文综述了纳米银合成方法和不同形状纳米银的最新研究进展,合成方法重点介绍了辐射法、激光烧蚀法、电化学法、光化学法和生物合成法,评述了这些方法的优缺点;同时从模板法、动力学、热力学以及氧化刻蚀4个方面介绍了纳米银形状控制的机理.介绍了聚合物纳米银复合材料的研究进展.     

超声引发无皂乳液聚合制备纳米银/PAAEM复合材料及其表征

在不使用气体保护及乳化剂的条件下,超声辐射引发无皂乳液聚合双原位合成纳米银/聚乙酰乙酸基甲基丙烯酸乙酯(PAAEM)复合材料。并通过XRD、FTIR、TEM、HRTEM、XPS和TG等分析方法对其进行表征。结果表明:纳米银粒子具有面心立方结构和球形或近球形形貌,且较均匀地分散在聚合物基体中;纳米银粒子与基体之间的相互作用是纳米银与基体中乙酰乙酸基的羰基氧原子配位所产生的;而且纳米银粒子对基体PAAEM的热学性能有很大影响。     

纳米银与基体P(AMPS-MMA)的相互作用研究

在无引发剂和还原剂的条件下超声辐射双原位合成出纳米银/2-丙烯酰氨基-2-甲基丙磺酸与甲基丙烯酸甲酯共聚物[P(AMPS-MMA)]复合物.TEM表明,纳米银粒子的粒径5~15nm,均匀地分散在聚合物基体中;UV-Vis表明,超声时间影响纳米银的粒径大小及粒径分布;FT-IR、UV-Vis和荧光光谱表明纳米银与基体P(AMPS-MMA)之间存在一定的化学作用力;XPS证明了纳米银与基体P(AMPS-MMA)的作用力为纳米银与聚合物中酯基氧原子之间通过配位作用形成的化学作用力.     

银/聚合物纳米复合材料

银/聚合物纳米复合材料是一种典型的聚合物基复合材料, 其结构和性能依赖于合成方法,因此开发材料的优异性能必须以深入研究纳米材料的先进合成技术为前提。本文综述了纳米银粒子及其与聚合物形成的纳米复合材料的最新合成进展, 重点介绍了基于液相化学还原方法合成纳米银粒子的新方法, 如溶胶-凝胶法、沉淀法、微乳液法和离子液体法, 以及纳米银粒子的分散技术和原位法合成银/聚合物纳米复合材料的新技术, 并介绍了纳米银复合材料的电绝缘性、表面增强拉曼散射性能、抗菌性及其在生物医学等领域中的应用。     

高分散纳米银/蒙脱土复合材料的制备及表征

In this paper, the nanosized silver particles with a narrow size distribution and high dispersivity located in both interior and exterior layers of montmorillonite as a confinement reactor by a chemical reduction method were prepared. It was found that the obvious changes of the particle size and dispersivity of the nanosilver located in both interior and exterior layers of montmorillonite did not occur after being treated by supercritical ethanol dried at the temperature of 270 ℃ and proven that the nanosilver/montmorillonite composites had a good thermal stability, which will have some potential applications as a high activity catalyst, antibacterial agents etc.     

聚合物/淀粉复合材料的制备与性能研究进展

淀粉是一种天然高分子材料,具有来源广泛、价格低廉、可再生、可降解等优点,在生物降解高分子材料领域中具有重要地位。淀粉塑化后较为柔软,类似于弹性体,如果能够用于聚合物的增韧改性,将对降低成本、保护环境有重要意义。目前,淀粉在聚合物共混改性中主要起填充、降低成本的作用,而作为弹性体增韧聚合物制备高抗冲聚合物复合材料还比较少。为了改善聚合物/淀粉复合材料的性能,可以采用淀粉塑化改性、淀粉化学改性、添加相容剂、添加弹性体协同淀粉增韧等方法。本文从以上4个方面总结了聚合物/淀粉复合材料的研究进展,讨论了目前聚合物/淀粉复合材料存在的问题,并对未来的发展方向进行展望。     

超声化学法制备树枝状纳米银的研究

Nanostructured silver dendrites were synthesized by using sonochemical method from an aqueous solution of AgNO₃ in the presence of isopropanol as reducing agent and polyethylene glycol (PEG) as disperser. The silver nanostructures were characterized by using TEM， XRD and EDS analysis. The effects of reducing agents， dispersers， concentration of AgNO₃ on the silver dendrites nanostructures were also invetigated. A well-defined nanostructured silver dendrite was prepared by ultrsonic irradiation of the aqueous solution of 0.04 mol·L^-1 silver nitrate， 4.00 mol·L^-1 isopropanol and 0.04 mol·L^-1 PEG400 for 1 h.     

纳米银负载三聚氰胺泡沫基相变复合材料的一步法制备及结构与性能

以轻质柔性的三聚氰胺泡沫(MF)作为基体,将其置于由乙二醇(EG)、硝酸银(AgNO₃)、聚乙烯吡咯烷酮(PVP)和氯化铜(Cu Cl₂)组成的反应溶液中,利用高温环境中发生的氧化还原反应在泡沫骨架上生成纳米银(Ag),随后通过真空浸渍法在泡沫基体中封装月桂酸(LA)制备相变复合材料.采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)和红外热成像仪等对制得的相变复合材料的形貌、结构和热性能进行研究.结果表明,当Ag NO₃浓度为4 mg/m L时,纳米Ag均匀致密地沉积在MF骨架表面,且同时存在Ag纳米粒子(Ag NPs)和Ag纳米线(Ag NWs)两种形态.相变复合材料的相变焓高达144.0 J/g,相变焓效率超过了80%,呈现出优异的温度调节和储热能力.本文提供了一种制备综合性能优异的相变复合材料的新策略,有利于拓宽相变复合材料的应用领域.     

共轭微孔聚合物及其复合材料的制备及应用

共轭微孔聚合物是一类具有扩展共轭体系的骨架材料,具有比表面积大、稳定性高、微孔大小和体积可精确调控等特点。由于其独特的结构特点,共轭微孔聚合物在各方面展现出巨大的应用潜力,本文综述了共轭微孔聚合物及复合材料的制备方法,以及共轭微孔聚合物在气体吸附和储存、污染物的富集、非均相催化、光发射、化学传感器、光捕集、电能存储等方面的应用。     

负载纳米银复合微球制备及其催化性能

以具有温度和pH双重敏感性能的N-异丙基丙烯酰胺(NIPAM)共聚丙烯酸(AA) P(NIPAM-co-AA)高分子微凝胶为模板, 以乙醇为还原剂, 原位还原得到负载纳米银的微米尺度Ag/P(NIPAM-co-AA)复合微凝胶材料. 通过扫描电子显微镜(SEM)、X射线衍射(XRD)仪和紫外-可见(UV-Vis)分光光度计等对复合材料的形貌、组成和催化性能进行表征. 研究结果表明, Ag/P(NIPAM-co-AA)复合微球具有均一的表面结构, 微凝胶的限域作用显著提高了纳米银的分散性和稳定性. 另外, Ag/P(NIPAM-co-AA)复合微球对对硝基苯酚(4-NP)的还原具有较好的催化活性, 且其催化活性与微凝胶网络结构的溶胀、收缩行为有一定关系, 即模板微凝胶的温敏特性可以实现对对硝基苯酚催化反应活性的调控作用.     

Preparation and Characterization of Aromatic Polybenzoxazoles Copolymers Containing 2,6-Naphthalene Units

A series of polybenzoxazoles(co)polymers bearing crankshaft units in the main chain was synthesized by the conventional solution polycondensation of 4,6-diaminorescinol dihydrochloride, terephthalic acid (TA) and 2,6-naphthalene dicarboxylic acid(NDA). All of the polymers show lyotropic liquid crystal behavior in polyphosphoric acid (PPA) and methanesulfonic acid (MSA). The polybenzoxazoles exhibit an excellent thermal resistance although the crankshaft monomer has been introduced into the polymer backbone. The temperature for the 5% weight loss of all the polymers is above 600 ℃. The X-ray diffraction analysis results show that the series of the polymers has a high crystallinity. The introduction of NDA makes a slight decrease in the thermal resistance of the polymers. The maximum absorption peak in the UV-Vis spectra can be adjusted according to the amount of 2,6-naphthalene units in the polymers, which indicates the potential application of the polymers as optoelectrie materials.     

Preparation, Characterization and Magnetic Properties of PANI/La-substituted LiNi Ferrite Nanocomposites

Magnetic nanocomposites containing polyaniline （PANI）-coated La-substituted LiNi ferrite （LiNi0.5La0.02Fe1.98O4） were synthesized by in situ polymerization in aqueous solution of hydrochloric acid. The nanocomposites exhibited the magnetic hysteresis nature under applied magnetic field. The saturation magnetization （Ms） and coercivity （Hc） varied with the ferrite content. The obtained nanocomposites were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FT-IR）, UV-Visible spectroscopy and vibrating sample magnetometer （VSM）. TEM and SEM studies showed that the nanocomposites present the core-shell structure. The results of XRD patterns, FT-IR and UV-Visible spectra indicated the formation of PANI-LiNi0.5La0.002Fe1.98O4 nanocomposites and showed that the interaction existed between PANI backbone and ferrite particles in the nanocomposites. The bonding mechanism in the nanocomposites has been proposed.     

Preparation and Properties of Layered Silicate Nanocomposites Based on Ethylene Vinyl Acetate Copolymers

(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler exfoliation were evidenced by X‐ray diffraction and transmission electron microscopy, respectively. Nanocomposites tensile properties showed that Young's modulus increases significantly even at very low content of the organo‐modified filler while preserving high ultimate elongation and tensile stress. The matrix thermal stability in air was increased by 40°C and, interestingly, the obtained nanocomposites present flame retardant properties.     

儿茶素-银纳米复合材料的制备及其应用

探索了以植物活性成分儿茶素作为还原剂和保护剂一步水热法合成儿茶素-银纳米复合材料,并进一步测试了纳米复合材料的抑菌活性。 紫外可见吸收光谱(UV-Vis)和红外光谱(FTIR)测定证明制备得到了儿茶素包裹的银纳米粒子。 透射电子显微镜(TEM)和X射线衍射(XRD)结果显示银纳米粒子的平均粒径为22.7 nm,并具有面心立方晶体结构。 抑菌活性实验结果表明,儿茶素-银纳米复合粒子对大肠杆菌、金黄色葡萄球菌以及白色念球菌都有很强抑制作用,尤其对白色念球菌的抑制作用最强,其最低抑制浓度(MIC)和最低杀菌浓度(MBC)分别为19.63和39.26 μg/mL。 儿茶素-银纳米粒子强抑菌活性可归因于其表面银离子的持续释放,有望应用于长效抑菌制剂产品。     

PMMA-TiO2纳米复合材料的制备

PMMA-TiO2纳米复合材料的制备;溶胶-凝胶法     

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征

聚苯乙烯/有机合成锂皂石纳米复合材料的制备与表征     

Preparation and Characterization of Copper Nanowire/Polyamide 6 Nanocomposites and Its Properties

Copper nanowire/polyamide 6 (denoted as nano-Cu/PA6) nanocomposites were readily prepared via in situ polymerization in reducing atmosphere. The microstructure, phase composition, and chemical state of typical elements of as-prepared nano-Cu/PA6 nanocomposites were analyzed by transmission electron microscopy, and X-ray diffraction, while their thermal stability and crystallization behaviors were evaluated by thermogravimetric analysis and differential scanning calorimetry. Moreover, the mechanical strength of as-prepared nano-Cu/PA6 nanocomposites was determined with a universal testing machine, and their friction and wear behaviors were evaluated with an MRH-3 high speed block-on-ring test rig. Findings indicate that copper nanowire is coated by surrounding molecular chains of PA6 and well disperses in the polymeric matrix. Besides, copper nanowire consists of metallic copper, which indicates that copper nanowire coated by PA6 matrix has good chemical stability and is not oxidized during the preparation of the title nanocomposites under high-temperature reactions. Furthermore, copper nanowire filler is able to remarkably improve the mechanical strength and wear resistance of polyamide 6. Particularly, nano-Cu/PA6 composite containing 0.5% (mass fraction) copper nanowire possesses the maximum tensile strength (its tensile strength is higher than that of pure PA6 by 77.41%); and its friction coefficient and wear scar diameter are also much smaller than those of PA6.     

Microstructural Characterization of Diblock Copolymers Formed by Styrene and Different Methacrylic Units

FT-IR, DSC, and NMR techniques allowed the structural characterization of four copolymers formed by styrene and methacrylic units (methacrylic acid (MAA), dimethylamine ethyl methacrylate (DMAEMA), sodium methacrylate (MANa), and 1-hydroxyethyl methacrylate (HEMA). The copolymer composition was studied by Fourier transform-infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The thermal behavior of the block copolymers was analyzed by differential scanning calorimetry (DSC). Three of the four copolymers showed two transitions caused by changes in the polymer heat capacity (ΔCp) of each block. Diffusion-ordered spectroscopy (DOSY) experiments were used to distinguish copolymer from homopolymer mixtures. Finally, the triad-level stereosequences of styrene-methacrylic copolymers were obtained using ¹³C NMR. The results indicate that by increasing the alkyl-substituent length in the methacrylic block, the probability of syndiotactic polymerization increases.     

Preparation,Characterization and Optical Properties of Hostguest Nanocomposite Material Mordenite—silver Iodide

Silver iodide nanoclusters were successfully prepared in the channels of mordenite by a heat diffusion method.Powder X-ray diffraction.adsorption technique and infrared spectroscopy were used to characterize the prepared materials,which showed that the guest silver iodied had been encapsulated in the channels of mordenite.The optical properties of the solid phase diffuse reflectance absorption of nanocomposite material NaM-AgI were studied,showing that the absorption bands of the diffuse reflectance absorption of the prepared material moved to the region of high energy.The absorption peak of the material prepared shifted to the region of high energy.Namely,blue shift was caused.This has demonstrated the incorporation of silver iodide into the channels of the zeolite.We observed the luminescence and surface photovoltage spectra of NaM-AgI sample,proposing the mechanisms of the photoluminescence and photovoltaic responses.     

Preparation and Rheological Characterization of Polymer Nanocomposites Based on Expanded Graphite

A new type of conductive filler, namely expanded graphite (EG), was used to prepare novel nanocomposites. The EG was incorporated into several rather different polymers, specifically polycarbonate (PC), low‐density polyethylene (LDPE), isotactic polypropylene (PP), and polystyrene (PS), using melt mixing in a small‐scale DACA‐Microcompounder. The EG content was varied between 1 and 20 wt%. The rheological properties and morphologies of the nanocomposites were characterized by melt rheology and scanning electron microscopy (SEM), respectively. The melt‐state linear viscoelastic properties were investigated using an ARES rheometer, with the measurements performed in the dynamic mode at various temperatures over a wide range of frequencies. Addition of the EG increased the linear dynamic moduli and melt viscosity of the materials. Up to a certain critical concentration of EG, the materials exhibited a simple liquid‐like behavior. Above this concentration, however, significant changes in the frequency dependences of the moduli and viscosity were observed. In addition, the moduli showed a liquid‐solid transition resulting in a second plateau in the low frequency‐regime, and the complex viscosity revealed shear‐thinning behavior. Specific values of this percolation concentration were found to be at around 4 wt% in the case of PC/EG, 9 wt% for PP/EG and PS/EG, and 12 wt% for PE/EG. This critical concentration was correlated to a network‐like structure formed through interactions between the EG platelets and the polymers. The extent of these complications was found to vary from polymer to polymer, presumably due to different degrees of EG exfoliation and dispersion arising from different EG‐polymer interactions and from variable shearing forces dependent on the polymer viscosities. The formation of network‐like structures is very sensitively displayed using van Gurp‐Palmen plots, which are most suitable for identifying “rheological percolation” in our investigated systems.