纳米镍/聚苯胺的原位合成及性能表征

【作者】 高雪梅；

【导师】 赵东宇；

【作者基本信息】 黑龙江大学 ， 高分子化学与物理， 2009， 硕士

【摘要】 纳米镍粉是一种重要的磁性金属材料,具有一系列独特的物理化学特性,在催化剂、磁性材料、导电浆料、电池材料及屏蔽材料等许多领域都有广泛的应用前景。因此,将纳米镍与聚苯胺进行原位复合,合成纳米镍/聚苯胺复合材料,实现两者电、磁性能的结合,在电磁屏蔽和化学催化领域可望具有重要应用价值。本研究采用1,2-丙二醇液相还原法,合成具有纳米尺度的金属镍粒子,并对合成条件、粒径控制和表面修饰进行了较为系统的研究。在此基础上分别采用了原位聚合和原位生成这两种方法制备了纳米镍/聚苯胺复合材料,并对其结构及性能进行了研究。在1,2-丙二醇还原体系中,分别使用了十二胺、聚乙烯吡咯烷酮(PVP)和油酸作为修饰剂,利用1,2-丙二醇还原相同母体乙酸镍,成功合成了具有面心立方结构的纳米镍粒子,制备形貌分别为球形、刺球形和雪花状。考察了修饰剂的浓度和NaOH的浓度对金属镍粒子的形貌和粒径的影响,利用傅立叶红外(FTIR)分析初步解释不同形貌纳米镍的形成机理。SEM研究发现:三种表面活性剂作为稳定剂能够抑制纳米镍粒子的生长,防止团聚,实验所得的镍粒子粒径最小可控制在50 nm;适宜浓度的NaOH可以制备出粒径小、分散性好的纳米镍粒子。FTIR发现纳米镍与修饰剂之间有一定的相互作用。抗酸性试验发现油酸修饰的镍粒子耐酸性最好。首次采用固体颗粒稳定乳液法(Pickering乳液),在油酸修饰的镍纳米粒子稳定的甲苯/水乳液中发生原位聚合,制备了纳米镍/聚苯胺导电复合材料。SEM研究发现:随着纳米镍含量的增加,纳米复合材料的形貌由纳米棒结构转变成纳米球或纳米纤维结构。FTIR及Raman结果表明:纳米镍与聚苯胺之间存在着较强的相互作用。四探针电导率测试表明:当纳米镍的质量含量为2 wt%时,电导率最大,复合材料的电导率达到极大值2.7 S/cm之后电导率逐渐下降。采用两步法先合成聚苯胺,再将聚苯胺分散到1,2-丙二醇体系中,分别采用三种表面活性剂作为修饰剂,在聚苯胺表面原位生成纳米镍,制备了纳米镍/聚苯胺复合材料。结果表明:镍粒子均匀地镶嵌在聚苯胺的表面,复合材料中的镍粒子呈面心立方结构,纳米镍与聚苯胺之间存在一定的相互作用。更多还原

【Abstract】 The nano-nickel powder is one of the most important magnetic metal materials applied widely in catalysis, magnetic materials, conductive materials and shielding materials due to their special physical properties. Therefore, the nano-Ni/PANI composites with both conducting and ferromagnetic properties have the important prospect in the field of electromagnetorheological shield and chemical catalysts. In this research, the nickel (Ni) nanoparticles were prepared with 1, 2-propanediol as the reductant. The synthetic condition, particle size-controlled and surface modification of the Ni nanoparticles were systematically investigated. Based on these studies, nano-Ni/PANI composites were prepared by in-situ synthesis and Pickering Emulsion polymerization, and the relations between their structures and properties were discussed.Ni nanoparticles with different morphologies, such as sphere, thorn-sphere and snowflake shape, were prepared by using nickel acetate as precursor, 1, 2-propanediol as solvent and reductant, with different surfactants as modifiers. These modifiers are laurylamine, polyvinyl pyrrolidone (PVP) and oleic acid, respectively. The effect of the concentration of modifier and NaOH on morphology and size of Ni nanoparticles were discussed. The systhesis mechanisms of Ni nanoparticles with different morphologies were investigated. SEM showed that different surfactants were important for preventing the Ni nanoparticles from agglomeration and uniformity of nanoparticles, the minimal size of Ni nanoparticles prepared was less than 50 nm and the concentration of NaOH strongly influenced on the size and the degree of agglomeration. The certain interaction between the modifiers and Ni nanoparticles was proved by FTIR. Ni nanoparticles modified by oleic acid responded for the good stability and acid resistance.Nano-Ni/PANI composites were prepared by a novel solids-stabilized emulsion (Pickering Emulsion) route for the first time. The sphere-like and nano-rod morphology of nano-Ni/PANI composites were synthesized in a toluene/water emulsion stabilized by oleic acid-stabilized Ni nanoparticles. SEM showed that morphology of the resulting Ni/PANI nanocomposites depended on the amount of Ni in the reaction system. The strong interaction between Ni nanoparticles and PANI was proved by FTIR and Raman. At the same time, their electrical properties of the nano-Ni/PANI composites were also affected by the content of Ni. The conductivities of nanocomposites reached the maximum value, 2.7 S/cm with 2 wt% Ni loading.The nano-Ni/PANI composites with the Ni content up to 20 wt% can be obtained by liquid phase reduction method in the presence of PANI. SEM images of nano-Ni/PANI composites showed that Ni nanoparticles were inlaid homogeneously in the surface of PANI. Ni nanoparticles were the typical diffraction patterns of single-phased and face-centered cubic (fcc) phase in the surface of nanocomposites, and the certain interaction between Ni nanoparticles and PANI was proved by FTIR and Raman.更多还原