纳米粒子的表面聚合物接枝改性

综述了纳米粒子与高分子聚合物复合的优点及不足,分析引起不足的原因,指出纳米粒子表面改性的重要性。同时在比较纳米粒子几种表面改性方法的基础上指出化学接枝改性的优越性,分析各种化学接枝改性方法及其有关的修饰机理和几种常用的表征方法。     

纳米氧化锌表面包覆改性及其表征

采用液相沉积法对纳米氧化锌进行表面包覆SiO2和SiO2/Al2O3改性,并用XRD、TEM、TG-DSC对其表面结构进行了表征,借助Zeta电位测定仪、静态沉降实验等分析手段考察了改性前后纳米氧化锌在水体系中的分散稳定性.结果表明,在ZnO表面形成的包覆物是以非晶态形式存在的,通过表面包覆SiO2和SiO2/Al2O3改性后明显提高了氧化锌的表面羟基含量,有效改变了氧化锌的等电点,显著提高了纳米氧化锌在水中的分散稳定性.     

轻质高导电镀银复合粒子的制备研究

采用分散聚合工艺,以聚乙烯吡咯烷酮为分散剂,偶氟二异丁腈为引发剂,无水乙醇为分散介质,制备出粒径2.0μm、表面光滑、分散均匀的聚苯乙烯微球.将其进行表面磺化处理后运用化学镀工艺制备出了具有轻质高导电特性的聚苯乙烯/银复合粒子.对所制备的复合粒子进行了扫描电镜、红外光谱以及体积电阻率的测试.结果表明:所制备的复合粒子包覆均匀、导电性能良好;表面修饰提高了PS微球表面的电负性和亲水性并引入了磺酸基团,对PS微球表面镀银起到了重要作用;另外,随着PdCl2浓度和AgNO3/PS质量比的增加,复合粒子包覆完整性和导电性能都随之增加,最佳体积电阻率为1.61×10 -4Ω·cm.     

Synthesis,characterization and surface modification of ZnCrFeO4 nanoparticles

The aim of this research was to investigate zinc chromium ferrite (ZnCrFeO₄) nanoparticles, synthesized using the sol gel technique with nanoparticle size controlled through a two-stage annealing process. Stage one was a low temperature firing which produced low quality nanocrystals with an average size of 15 nm. This was followed by a second firing stage at high temperature which enhanced the crystal quality. The nanoparticles were then coated with a bio-compatible shell to form a stable suspension in the ferrofluid carrier. The resulting nanoparticles were found by electron microscopy, atomic force microscopy and X-ray diffraction studies to have excellent crystal quality. The average size was 8.5 nm. Preliminary cell culture studies indicated the ZnCrFeO₄ nanoparticles were non-toxic. The relatively high measured value of the relaxivity r₂ showed that the nanoparticle coating was effective in substantially reducing aggregation and enhancing the properties of the nanoparticles associated with contrast enhancement in MRI.     

纳米铁粉吸波剂的表面改性及其分析表征

采用油酸和KH-560对纳米铁粉进行改性,通过红外光谱、热分析、透射电镜等方法对改性后粒子进行了表征和研究,结果表明,油酸对纳米铁粉的改性效果明显优于KH-560改性,而且油酸还有去除纳米铁粉表面氧化层的作用.     

生物医用磁性纳米颗粒的制备与表面改性

磁性纳米颗粒目前是生物医用纳米材料领域异常活跃的方向之一.不同方法制备的磁性纳米颗粒经不同聚合物或分子表面改性后具有多方面的生物医学应用.本文综合评述了磁性纳米颗粒的制备方法,如共沉淀法、溶胶-凝胶法、微乳剂法等;总结了磁性纳米颗粒表面改性技术,包括改性物质与改性方法;概括了磁性纳米颗粒在生物医学领域的应用,主要涉及磁靶向制剂、细胞分离、肿瘤细胞的过热治疗、MR I衬度增强剂四方面.磁性纳米颗粒还有很大的发展空间和广阔的应用前景.     

Hydrothermal synthesis and characterization of monodisperse α-Fe2O3 nanoparticles

Monodisperse α-Fe₂O₃ nanoparticles have been successfully prepared by hydrothermal synthetic route using FeCl₃, CH₃COONa as reagents and reacted at 200 °C for 12 h. The morphology and structure of products were characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the α-Fe₂O₃ nanoparticles were single-crystalline hexagonal structure and average diameters were about 80 nm. Magnetic properties have been detected by a vibrating sample magnetometer at room temperature. The nanoparticles exhibited a ferromagnetic behavior with the coercive force (Hc), saturation magnetization (Ms) and remanent magnetization (Mr) was 185.28 Oe and 0.494 emu/g, 0.077 emu/g.     

具有核壳结构的纳米CaCO3@SiO2的制备与表征

采用简单的溶胶-沉淀法制备了具有核壳结构的纳米CaCO3@SiO2复合产物。用X-射线衍射、电子扫描显微镜、X-射线能谱以及耐酸性测试等方法对粒子的包覆效果、化学组成等做了分析和表征。结果表明,用硬脂酸改性后的碳酸钙比较容易包覆无机的SiO2,SiO2在CaCO3表面包覆后形成了CaCO3为核,SiO2为壳的核壳结构。     

Cu diffusion in α-Fe: determination of solute diffusivities using atomic-scale simulations

The nucleation and growth of radiation-induced Cu-rich clusters have proved an important topic in the study of microstructural and chemical evolution responsible for property changes in pressure vessel steels subjected to neutron irradiation. Small Cu clusters can act as precipitate precursors and contribute to the hardening of the material by impeding dislocation glide. Reliable Cu diffusion coefficients provide critical input to Monte Carlo and rate theory approaches to study the kinetics of diffusion and clustering that lead to the formation of such Cu-rich features. In this paper we report the results of a molecular dynamics study of Cu solute-atom diffusion in a Fe–0.9at%Cu alloy, using high-temperatures and high-vacancy concentrations to hasten the convergence of the calculation. We find a value of 0.61 eV for the migration energy of Cu in the b.c.c Fe matrix, in good agreement with available experimental results. The main diffusion mechanisms under the conditions simulated are identified and discussed, and the effect of vacancy and solute clustering on Cu migration is assessed. In addition, a rigorous computation of the solute enhancement factor, correlation factor and solute diffusivity is performed within the five-frequency theoretical framework and the harmonic approximation. The results obtained are compared with those yielded by the direct MD simulations and the observed differences discussed.     

纳米氧化锌的气流粉碎改性及应用研究

利用气流粉碎改性工艺,以硬脂酸为改性剂,对纳米氧化锌进行解团聚和表面改性,并借助SEM、XRD、FT-IR和激光粒度分析等对改性产品进行了表征,探讨了改性纳米氧化锌在天然橡胶中的应用。结果表明,与改性前相比,改性纳米氧化锌的解团聚效果明显;颗粒表面亲油疏水,在有机溶剂中有较好的分散性;并且能较好地提高天然橡胶的硫化性能和力学性能。证明该工艺对纳米氧化锌进行表面改性是可行的。     

亲油性LaF3纳米粒子的制备及表征

在醇-水混合溶剂中合成了表面为油酸修饰的LaF3纳米粒子,并用透射电子显微镜、红外光谱和X射线粉末衍射仪对修饰LaF3纳米粒子进行了表征.结果表明:所制备的修饰LaF3纳米粒子大小均匀,粒径约为8nm;其纳米核为六方结构的LaF3;由于表面修饰剂油酸与LaF3纳米粒子表面之间发生化学键合作用,使得油酸修饰LaF3纳米粒子在苯及润滑油中的分散性明显提高.     

Study of autoabsorption for total α and β counting

The RaMsEs Group (Radioprotection et Mesures Environnementales) of the IPHC performs research and offers services mainly in the field of radioactivity measurements and sample analysis. This report will describe some of our recent experience using a semiautomatic evaporation system to prepare large area thin deposits for total α and β counting and gives experimental and simulated results for the autoabsorption coefficients.     

CoFe_2O_4@FeCo纳米核壳颗粒的制备与磁性研究

利用化学共沉淀法合成Co Fe2O4纳米颗粒,并在氢气气氛下还原获得Co Fe2O4@Fe Co核壳结构磁性纳米颗粒。用XRD和TEM对所得样品进行结构分析,用SQUID测量样品在300 K时的磁滞回线,发现随着壳厚度的增加,核壳结构样品的矫顽力呈现先增加后减小的趋势,而其饱和磁化强度表现出逐渐增加的趋势。为了探究所制备样品的核壳磁性层之间的交换相互作用,还测量了M-T曲线以及T=5 K时的零磁场冷却(ZFC)和带磁场冷却(FC)磁滞回线。     

聚吡咯的制备、改性及应用进展

介绍了聚吡咯的导电机理和制备方法,重点综述了近几年来聚吡咯的改性方法以及聚吡咯在相关领域的应用进展。     

单分散Fe3O4纳米粒子的合成、表征及其自组装

采用高温有机前驱体分解法,以Fe(acac)3为前驱体制备出单分散性较好的Fe3O4纳米粒子,粒径为(6.4±0.90)nm.利用TEM、XRD、HPPS、FTIR等手段对粒子的形貌及性质进行了研究,证实得到的是Fe3O4单晶,粒子表层的铁原子通过共价键和油酸分子中-COO的两个氧原子结合在一起.通过对自组装过程的初步研究表明随磁性纳米粒子浓度的增加,粒子排布逐渐由零星的无规排列变为规整的单层和多层有序结构.     

芳纶纤维表面改性技术及相关机理的研究进展

综述了目前国内外芳纶表面改性的常用方法及研究进展,介绍了芳纶结构对界面粘结性及复合材料力学性能的影响,并对芳纶接枝改性的机理进行了探讨,认为根据分叉纤维模型理论,接枝改性法可以有效提高复合材料性能.