【作者】 张方志；

【导师】 苏致兴；

【作者基本信息】 兰州大学 ， 高分子化学与物理， 2008， 博士

【摘要】 论文详细介绍了无机粒子（无机粉体）表面修饰（表面改性）的发展过程，全面论述了无机粒子表面修饰在材料科学中的重要意义以及在复合材料中不可替代的功能性作用，无机粒子的表面修饰已成为“超细无机粉体技术和工程研究”的重要组成部分。论文综述了无机粒子表面修饰的各种方法及表征手段，掌握了该领域的最新进展和研究热点。论文立足于无机粒子表面修饰的新方法，详细研究了无毒环保阻燃材料——氢氧化镁；磁性材料——四氧化三铁、镍粒子的表面修饰，取得了如下成果：一、微米级及纳米级氢氧化镁（Mg（OH）₂）的表面修饰及表征。采用超声波方法将硬脂酸修饰在Mg（OH）₂表面，经红外（FT-IR）、X-射线光电子能谱（XPS）和元素分析（EA）分析证明硬脂酸键合在了Mg（OH）₂表面（即SA-Mg（OH）₂），包覆层厚度为1.3 nm。显微镜观察SA-Mg（OH）₂在二甲苯中分散均匀，将其在二甲苯中进行沉降实验及在液体石蜡中的粘度进行评价，均证明该修饰方法是成功的。将修饰后的氢氧化镁（SA-Mg（OH）₂）与聚丙烯复合，对修饰效果作了直接评价。复合材料的熔融指数显示SA-Mg（OH）₂可改善材料的流动性，材料的冲击强度和断裂伸长率也有所提高，表明SA-Mg（OH）₂与聚丙烯有良好的相容性。采用一步法将油酸修饰在纳米Mg（OH）₂表面，FT-IR证明油酸分子牢固地键合到了氢氧化镁表面上；漂浮实验测试氢氧化镁表面性质，发现当油酸用量为6％时氢氧化镁的活化指数达到98．9％，显示其表面呈强烈地疏水性。采用表面引发原子转移自由基聚合法（SI-ATRP）制备了聚苯乙烯接枝氢氧化镁纳米复合粒子（PS-Mg（OH）₂）。先合成了溴代异丁酸修饰的纳米氢氧化镁作为大分子引发剂，然后采用SI-ATRP方法获得了聚苯乙烯接枝修饰的氢氧化镁纳米粒子。FT-IR分析证明聚苯乙烯键合在了Mg（OH）₂表面；经由元素分析（EA）可知接枝率和单体转化率随反应时间线型增大，凝胶色谱（GPC）测试接枝的聚苯乙烯分子量分布较小（PDI<1．3），体现出明显的活性可控聚合特征，聚合12 h粒子的接枝率达到115％；TEM观察PS-Mg（OH）₂粒子在甲苯中呈现很好的分散性，将其在甲苯中进行沉降实验及评价在液体石蜡中的粘度，均证明PS接枝修饰Mg（OH）₂粒子能改善其在有机介质中的分散性。通过原位聚合法制备了聚苯乙烯接枝氢氧化镁纳米复合粒子（PS-Mg（OH）₂）。先合成了油酸修饰的纳米氢氧化镁粒子，后通过无皂乳液聚合制备了聚苯乙烯接枝氢氧化镁纳米复合粒子。FT-IR分析证明聚苯乙烯键合在了Mg（OH）₂表面；经由EA分析可知聚苯乙烯的接枝率为29．1％；透射电镜（TEM）观察到PS-Mg（OH）₂粒子均匀分散在了聚苯乙烯中；差式扫描量热法（DSC）、热失重（TGA）测试PS／PS-Mg（OH）₂复合材料的热性能，证明复合粒子能提高材料的热稳定性。二、磁性纳米粒子的合成、表面修饰及表征。采用接枝（“grafting from”）方法制备了聚苯乙烯接枝四氧化三铁纳米复合粒子（PS-Fe₃O₄）。先合成了γ-甲基丙烯酰氧基丙基三甲氧基硅烷修饰的四氧化三铁纳米粒子，然后与苯乙烯共聚，从而将聚苯乙烯接枝在Fe₃O₄粒子上。经FT-IR分析证明聚苯乙烯键合在了Fe₃O₄表面，EA可知聚苯乙烯的接枝率为71％；TEM观察到PS-Fe₃O₄复合粒子在甲苯中分散好，评价其在液体石蜡中的粘度，证明PS接枝修饰Fe₃O₄粒子能改善其在有机介质中的分散性；振动样品磁强计（VSM）测试复合粒子具有超顺磁性，XRD分析接枝聚合没有改变Fe₃O₄的结晶结构。制备了镍@二氧化硅@苯乙烯-丙烯腈-硅单体三元共聚物纳米复合粒子（Ni@SiO₂@AS）。先合成了二氧化硅包覆的镍粒子，后采用接枝（“grafting to”）方法将三元共聚物接枝到粒子上。二氧化硅包覆镍粒子核，保护了镍核不被氧化。FT-IR分析证明三元共聚物包覆在了粒子表面，由EA可知接枝率为3．5％；TEM观察到复合粒子在甲苯中分散好；VSM测试复合粒子具有镍的超顺磁性。Ni@SiO₂@AS纳米复合粒子在甲苯中分散性好，证明所采用的修饰方法是成功的，具有较高的实用性。该修饰方法为把纳米磁性镍粉分散到聚烯烃树脂（ABS、PS、AS等）中，制备优质聚烯烃／镍纳米复合材料提供了一条有价值的途径。更多还原

【Abstract】 Surface modification of inorganic particles has been an important part of "ultrafine inorganic powders technology". This paper introduced the evolvement of the surface modification of inorganic particles （inorganic powders）, described the importance of the surface modification of inorganic particles in materials science and composites. The surface modification methods and characterization techniques were present in detail as well. The latest development and study was hold.This paper focused on new surface modification methods, investigated how to modify magnesium hydroxide （a nontoxic and environmentally friendly material）, iron oxide and nickel （magnetic materials）, and achieved the following results:1. Surface modification and characterization of micron/nanometer magnesium hydroxide （Mg（OH）₂）.The ultrasonic approach was utilized to modify magnesium hydroxide with stearic acid. Fourier transition infrared spectroscope （FT-IR）, X-ray photoelectron spectroscope （XPS） and element analysis （EA） proved stearic acid was covalently bonded to Mg（OH）₂ particles’ surface （SA-Mg（OH）₂）, and the encapsulation thickness was 1.3 ran. SA-Mg（OH）₂ could be well dispersed in xylene, as been observed by microscopy. The success of this method was evaluated by the sedimentation of SA-Mg（OH）₂ in toluene and the viscosity of SA-Mg（OH）₂ in liquid paraffin.The composite of PP/SA-Mg（OH）₂ was prepared to evaluate this modification method directely. In contrast to the untreated magnesium hydroxide, the rheology and mechanical properties （failure tensile rate and impact strenth） of the composite of PP/SA-Mg（OH）₂ could be improved.The hydrophobic Mg（OH）₂ nanparticles were accomplished by a simple one-step wet precipitation method using oleic acid as the modifier, Because of the adsorption oleic acid onto their surface, Mg（OH）₂ nanoparticles became hydrophobic. And the hydrophobic Mg（OH）₂ nanoparticles could be dispersed in toluene well, which was favorable for the process and properties of Mg（OH）₂/polymer composites. Polystyrene grafted magnesium hydroxide （PS-Mg（OH）₂） nanoparticles were prepared by in situ polymerization. FT-IR proved PS chains were immobiled to Mg（OH）₂ particles’ surface, and the grafting percentage was 29.1% by EA. TEM observed that magnesium hydroxide particles were dispersed in the composite with nanometer size, and PS/PS-Mg（OH）₂ nanocomposite had better thermal stability compared with neat PS resin.Polystyrene grafted magnesium hydroxide （PS-Mg（OH）₂） nanoparticles were prepared by surface-initiated atom transfer radical polymerization （SI-ATRP）. The macro-initiator, magnesium hydroxide nanoneedles modified by bromisobutyric acid, was synthesized first, followed by grafting reaction. FT-IR indicated that polystyrene had been successfully grafted onto the surface of Mg（OH）₂ nanoparticles. EA and GPC suggested polymerization with the controlled/"living" characteristics. By evaluating the sedimentation of SA-Mg（OH）₂ in toluene and the viscosity of SA-Mg（OH）₂ in liquid paraffin, a conclusion could be made that the dispersibility of Mg（OH）₂ nanoparticles in organic solvents could be remarkably improved by the grafting polymerization of PS.2. Preparation, surface modification and characterization of magnetic nanoparticles.PS grafted Fe₃O₄ nanoparticles （PS-Fe₃O₄） were accomplished by a "grafting from" process. The dispersibility of Fe₃O₄ nanoparticles in organic solvents could be remarkably improved by the grafting PS. The grafting polymerization did not change the crystalline structure of Fe₃O₄ nanoparticles, but lowered the saturation magnetization. In addition, Fe₃O₄ /cotton-fiber magnetic fiber was prepared via chemical deposition method.Nanoparticles of nickel coated by silicon coated by copolymer of polystyrene-acrylonitrile （Ni@SiO₂@SAN） were prepared by three steps: （i） the nickel metal nanoparticles is synthesized by chemical reduction using potassium borohydride; （ii） the nickel nanoparticles is coated by silicon and annealed; and （iii） the polystyrene-acrylonitrile chains are adsorbted on the surface of particles. The hybrid nanoparticles were resistant to oxidation, resulting from the protection of silicon. FT-IR proved polymer chains were immobiled to the particles’ surface, and the grafting percentage was 3.5% by EA. TEM observed that the composite nanoparticles were dispersed well in toluene, and VSM suggested the particles maintained the supra-paramagnetism of nickel.The good dispersion of modified particles in organic mediums indicated that modification techniques were successful and could be utilized in future.更多还原