【作者】 高其标；

【导师】 申屠宝卿； 翁志学；

【作者基本信息】 浙江大学 ， 化学工程， 2002， 硕士

【摘要】 随着科学技术的日益发展，对材料的功能要求越来越高。由于有机-无机复合材料兼具有两者的优越性能而受到普遍欢迎，特别是随着纳米材料的发展，纳米填料已经被广泛研究和应用，并被证明是提高材料性能的好方法。但由于纳米填料本身的局限性，即它的易团聚性和与有机基体的极性差异，限制了其发展和应用。本文在解决纳米颗粒的易团聚性和改善纳米颗粒表面性能方面进行了详细研究。 通过TEM、SEM、FTIR等方法研究了商品纳米SiO₂的颗粒形态、团聚程度、颗粒表面特性等。研究发现，商品纳米SiO₂颗粒表面虽经过表面处理剂处理，但仍以团聚体形式存在，其粉体颗粒尺寸远远超出纳米级范围，平均粒径为1300～1400nm，使之不容易均匀分散在有机高分子材料中。为改善商品纳米SiO₂在有机高分子材料中的分散性，采用苯乙烯原位乳液聚合的方法，对团聚的SiO₂粉体进行剥离再分散，并改善颗粒表面特性。 本文着重研究商品纳米SiO₂存在下苯乙烯原位乳液聚合的聚合动力学，及聚合工艺对团聚SiO₂剥离程度的影响。乳液聚合反应采用的乳化剂分别是阴离子型乳化剂十二烷基硫酸钠（SDS），非离子型乳化剂辛基苯基聚氧乙烯醚（OP-10）和复合乳化剂体系。研究单体浓度、乳化剂种类和浓度、单体和商品纳米SiO₂的配比、乳液固含量、引发剂浓度、反应温度、加料方式等对复合乳液粒径的影响。实验结果表明，随着聚合反应的进行，聚合转化率增加，而复合乳液的粒径逐渐减小，当反应转化率达到最大时，复合乳液粒径也达到最小值且保持不变。即随着聚合反应的进行，商品纳米SiO₂团聚体被逐渐剥离，使其分散到纳米尺寸范围内。研究还发现，反应体系采用SDS和OP-10的复合乳化剂时，复合乳胶颗粒粒径优于单一的SDS和OP-10乳化剂，且乳液稳定性高。 通过TEM、SEM观察了复合乳胶粒的颗粒形态和颗粒尺寸，发现复合乳胶粒子中的团聚纳米SiO₂被聚苯乙烯剥离为15～20nm的纳米粒子。FTIR结果证明，经索氏抽提器萃取后的复合粒子表面有聚苯乙烯接枝层存在，采用自制的动态法接触角测量装置测量复合粒子的接触角的变化，进一步证明了纳米 tSLrtdegrdedethtert颗粒表面聚苯乙烯接枝层的存在，使粒子的亲油性增加。 通过原位乳液聚合方法处理的纳米S。rps颗粒直径最小可达到77．Inm，同时还改善了颗粒表面的极性，增加其与聚合物基体的相容性，使之良好地分散在有机高分子材料中。不同于一般的纳米粒子表面处理方法，本方法具有操作简单、可控性好、成本低等特点，具有一定的工业放大优势。更多还原

【Abstract】 With a progress in science and technology, materials having diversity and high functionality have been highly required. In particular, composite materials combining characteristics of each component have attracted attention. Recently the incorporation of inorganic nanoparticle fillers into polymers had been proved to be an effective way for the improvement of the mechanical properties of polymers. However, the control of the interface and the dispersion of the nanoparticle in polymeric materials were considered to be the greatest importance in these nanocomposite materials. It was required to control the aggregation to enhance the interfacial interaction between different materials.In this thesis, firstly, the property of the commercial nano-Si02 was investigated. According to the result of TEM, SEM and the Coulter LS particle size analyzer, it was found that the particles of the commercial nano-SiO, were in the state of aggregation, and their diameter was over the range of nanometer (1300-l400nm). The purpose of the research was to separate the aggregation and to modify the surface of the commercial nano-Si02.An in-situ emulsion grafting polymerization method was applied to modification of the commercial nano-Si02 particles, and the modified nano-Si02 can be added to polymeric materials for improving their mechanical performance using existing compounding techniques. The dynamics of the in-situ emulsion grafting polymerization of styrene (St) in the presence of the commercial nano-Si02 were studied. Surfactants used were sodium dodecyl sulfate (SDS) and capryl phenyl polyoxyethylene ether (OP-lU). The effect of the surfactants concentration, monomer concentration, reaction temperature, and quantity of the commercial nanoSi02 on the diameter of particles was studied. Experimental results showed that the size of microcapsulate decreased with the increase of reaction conversion, the particles of the aggregation was exfoliated gradually. In the presence of the surfactant of SDS and OP-lU, the degree of exfoliation was good and the stability ofiiithe emulsion was also very good.The TEM photograph showed that the microcapsulate had the shape of core-shell and its size was in the range of nanometer. The result of Coulter Ls particle size analyzer also showed that the diameters of microcapsulate were in the range of nanometer. FTIR spectrum approved that polystyrene had been grafted on the commercial nano-Si02 surface by in-situ emulsion grafting polymerization.It was found that the diameter of the modified nano-Si02 could reach to 77.1 run and had good repetition. Unlike the other approaches for modification of nanoparticles, the current technique had many advantages, such as simpleness, low cost, easiness to be controlled.更多还原