【作者】 邰晓曦；

【导师】 程江；

【作者基本信息】 华南理工大学 ， 化学工程， 2011， 博士

【摘要】 无机-有机杂化材料是一种分散均匀的多相材料,在光学透明性、可调折射率、力学性能、耐温性能、耐磨性、柔韧性、功能性等方面具有明显的性能优势,在涂料领域有着重要的应用,采用无机金属氧化物粉体材料如Al₂O₃、TiO₂等改性有机聚合物已经成为无机-有机杂化材料研究的一个重要方面。与传统金属氧化物粉体相比,金属氧化物介孔材料拥有更大的表面积,特殊的结构特征,如孔道和空腔,具备更多的催化点或反应点。选用铈锆复合氧化物介孔材料对有机聚合物进行改性,通过介孔粒子在聚合物基体中的均匀分散,达到聚合物分子既能包覆在无机粒子外部,又能在粒子的孔内部生长的目的;同时,介孔结构材料的一维和三维孔洞结构有可能使聚合物分子链穿过粒子形成“无机-有机互穿网络”结构,能够将铈锆复合氧化物介孔粒子的多孔性、孔内可反应性、刚性、尺寸稳定性和热稳定性与聚合物的韧性、易加工性及介电性能等很好地结合起来,改善聚合物的断裂韧性、抗弯曲强度及抗高温氧化性等,获得高性能的无机-有机杂化材料,具有重要的现实背景和研发意义,为此,本文开展了以下四个方面的研究:（1）采用嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯（P123）为模板剂的软模板合成路线,利用水热合成法,制备CeO₂-ZrO₂介孔结构材料。研究不同铈锆摩尔比、焙烧温度、升温速率、晶化和陈化行为对材料的介孔结构、比表面积大小、孔径及其分布等方面的影响。分析CeO₂-ZrO₂的晶体结构,观察材料的表面和孔道结构,确定了制备最大比表面积CeO₂-ZrO₂介孔结构材料的最佳反应参数,即铈锆摩尔比为6:4,焙烧温度400°C,焙烧时间8h。实验结果还表明:当晶化温度过高时,介孔材料的比表面积将下降,而适当的陈化有利于介孔材料的粒度分布变窄。在焙烧阶段加快升温速率有利于保持更多完整的介孔结构,提高材料的比表面积,但过高的焙烧温度会使介孔材料的晶化程度增加,晶粒长大并在表面发生一定程度的烧结,粒径变大,颗粒间发生聚集而导致介孔材料的比表面积显著下降。（2）选用月桂酸、硬酯酸、油酸和硅烷偶联剂γ―甲基丙烯酰氧基丙基三甲氧基硅烷（KH570）四种有机分子对CeO₂-ZrO₂介孔粒子进行有机改性,研究有机改性剂对介孔粒子在非极性溶剂中分散性的影响。确定了油酸和硅烷偶联剂KH570作为CeO₂-ZrO₂介孔粒子的有效改性剂,制备出CeO₂-ZrO₂-PMMA接枝聚合物,探讨PMMA接枝改性CeO₂-ZrO₂介孔材料的机理和效果。结果表明:油酸对介孔粒子的有机改性是物理吸附和化学键合的共同结果,硅烷偶联剂KH570改性CeO₂-ZrO₂介孔材料的效果则受到反应时间和pH值的影响。油酸和KH570改性后的CeO₂-ZrO₂介孔粒子在非极性溶剂中具有良好的分散性和稳定性,便于进一步采用“由表面接枝法”,引发PMMA在CeO₂-ZrO₂介孔粒子上的接枝反应,得到的CeO₂-ZrO₂-PMMA接枝聚合物的热分解温度高于纯PMMA。由于在CeO₂-ZrO₂-PMMA的接枝链上存在活性端基,有利于进一步制备出新型的无机-有机杂化材料。（3）以苯乙烯和油酸改性后的介孔CeO₂-ZrO₂粒子为原料,采用原位聚合法制备出CeO₂-ZrO₂-PS杂化材料。研究CeO₂-ZrO₂-PS的杂化机制以及反应参数对聚苯乙烯分子量的影响,利用红外光谱、比表面分析、TEM、TG等多种方法对CeO₂-ZrO₂-PS杂化材料进行分析和表征。考察油酸含量和CeO₂-ZrO₂含量对CeO₂-ZrO₂-PS杂化材料拉伸强度和缺口抗冲击强度的影响,探讨CeO₂-ZrO₂刚性介孔粒子改善聚苯乙烯力学性能的机理。结果表明:CeO₂-ZrO₂粒子与苯乙烯基体间的界面粘结作用增强,可以有效改善聚苯乙烯的拉伸强度、缺口抗冲击强度等力学性能和耐热性能。相对于纯的聚苯乙烯热分解温度而言,CeO₂-ZrO₂-PS杂化材料的耐热性能增强,热分解温度提高。（4）使用硅烷偶联剂KH570对介孔CeO₂-ZrO₂粒子进行改性,采用共混法制备出CeO₂-ZrO₂-环氧树脂杂化材料。利用红外光谱、TEM、DSC、TG等多种方法对CeO₂-ZrO₂-环氧树脂杂化材料进行表征和分析;研究CeO₂-ZrO₂-环氧树脂固化物的力学性能;探讨CeO₂-ZrO₂刚性介孔粒子在环氧树脂体系中的共混行为以及固化后力学性能改善的机理。结果表明:添加CeO₂-ZrO₂的环氧树脂固化后的拉伸性能,缺口抗冲击性能和弯曲强度随着CeO₂-ZrO₂含量的增加呈先增大后减小的趋势,适当含量的CeO₂-ZrO₂粒子可以使CeO₂-ZrO₂-环氧树脂固化后的多项力学性能得到优化,邵氏硬度提高,耐热性能提高。引入脆韧转变的“逾渗模型”,初步建立有机改性CeO₂-ZrO₂介孔粒子在环氧树脂中共混行为的数学模型,解释杂化体系中不同含量的CeO₂-ZrO₂介孔粒子对杂化材料力学性能造成影响的原因。更多还原

【Abstract】 Inorganic-organic hybrid materials are heterogeneous materials with good dispersion, which have important applications in the area of coating preparation. These materials have the obvious performance advantage in the fields of optical transparency, adjustable refractive index, mechanical property, heat resistance, abrasive resistance, flexibility and functionality. At the present time, one of the most important aspects in inorganic-organic hybrid materials research is modifying polymer by using different inorganic metallic oxide particles such as Al₂O₃,TiO₂, etc.Compared with traditional metallic oxide particles, metallic oxide mesoporous materials have larger specific area, peculiar structural characteristic such as pore canal and cavity, possessing more catalytic and reactive sites. The cerium–zirconium mixed oxide mesoporous materials are uniformly dispersed in the polymer matrix and organic molecules can not only be coated on the surface of mesoporous particles, but also be filled in the pore canal when polymer matrix is modified by these mesoporous particles. Meanwhile, the one or three dimensional pore canal structure make it easy forming“Organic-Inorganic Interpenetrating Networks”when polymer chain threading into pore canal. Thus, the features such as porosity, reactivity, rigidity, dimentional stability and heat stability of cerium–zirconium mixed oxide mesoporous particles are combined with ductility, good dielectric properties and easy processing performance of polymer matrix, which improve fracture toughness, bending strength resistance and high temperature oxidation resistance of polymer dramatically. In this way,high-performance of inorganic-organic hybrid materials can be obtained. Based on these facts, research of the mesoporous materials modifying polymer matrix has practical value and we are focusing on studies as follows:CeO₂-ZrO₂ mesoporous materials were synthesized after calcinations by the way of using block copolymers P123 as templates, zirconium chloride octahydrate（ZrOCl2·8H2O） and cerium nitrate hexahydrate（Ce（NO3）3·6H2O） as raw materials. The effects of cerium/zirconium molar ratio, calcinations temperature, heating rate, crystallization and aging behavior on mesopore structure, specific areas, pore diameter and its distribution of mesoporous materials were investigated. The crystal structure of CeO₂-ZrO₂ was studied and the morphology of the CeO₂-ZrO₂ mesoporous materials was examined. The optimum parameters of largest specific areas of CeO₂-ZrO₂ are determined when the Ce/Zr molar ratio is 6/4, the calcinations temperature is 400°C and the calcinations time are 8 hours. Other experiment results also reveal the specific areas of mesoporous materials will decrease when the crystallization temperature is above certain temperature and the pore diameter distribution will become narrow when aging time is appropriate. Increasing heating rate at calcinations stage is beneficial for maintaining intact mesoporous structure and increasing mesoporous specific areas. However, excessively high temperature is harmful for large specific areas if the particles gather together for the reason of crystalline grain growing up and sintering.To enhance the interfacial interaction of cerium–zirconium mixed oxide mesoporous particles in filled polymer composites, an organic grafting method was applied to modify mesoporous materials by treating with lauric acid, stearic acid, oleic acid and silane coupling agent （γ-methacyloxypropyl trimethoxy silane）, and effects of these organic agents on dispersing mesoporous particles in the non-polar solvent were studied. It proves that the oleic acid and silane coupling agent are effective organic agents for mesoporous particles. The CeO₂-ZrO₂-grafted PMMA was synthesized and the grafting mechanism or effects was discussed. The results illustrate that the oleic acid modification for mesoporous particles is a common result of physical adsorption and chemical bonding. The effect efficiency of silane coupling agent modification is influenced by the reaction time and pH value. The mesoporous particles modified by oleic acid and silane coupling agent have favorable dispersibility and stability in the non-polar solvent, which imply that we can initiate polymethylmethacrylate （PMMA） grafting polymerization onto the mesoporous particles. The heat decomposition temperature of PMMA grafted CeO2–ZrO2 is higher than that of pure PMMA, which demonstrates that the CeO2–ZrO2 mesoporous materials are potential superior performance filler into thermoplastic polymers to improve polymer properties. Meanwhile, the active groups existing on the CeO₂-ZrO₂-grafted PMMA chain are beneficial for preparing new kinds of inorganic-organic hybrid materials.CeO₂-ZrO₂-PS hybrid materials were prepared with styrene and CeO₂-ZrO₂ mesoporous particles modified by oleic acid in situ polymerization. Different influences of reaction parameter for polystyrene molecular weight and hybridization mechanism were studied. The characteristics of hybrid materials were investigated by using infrared spectrum, N2 adsorption-desorption instrument, TEM and thermo-gravimetric analysis. Various contents of oleic acid and mesoporous particles, which influenced tensile strength and impact strength of hybrid materials were examined, and the mechanism of improving polystyrene mechanical property by mesoporous particles was discussed. The results reveal that the interface cohesive force is increased between the CeO₂-ZrO₂ particles and polystyrene matrix so that the mechanical property such as tensile strength, impact strength and heat resistance performance of polystyrene are greatly improved. Compared with pure polystyrene thermal decomposition temperature, the thermo-stability of CeO₂-ZrO₂-PS is improved significantly.CeO₂-ZrO₂-epoxy hybrid materials were prepared by blending method after modifying CeO₂-ZrO₂ mesoporous particle with silane coupling agent （γ-methacyloxypropyl trimethoxy silane）. The characteristics of hybrid materials were investigated by using infrared spectrum, TEM and thermo-gravimetric analysis,and the mechanical property of hybrid materials was examined. Blending behavior of CeO₂-ZrO₂ mesoporous particles in the epoxy and mechanism of mechanical property improvement were also explored. The results show that thermo-stability of cured CeO₂-ZrO₂-epoxy is improved after adding mesoporous particles into epoxy resin. The tensile strength, impact strength and flexural strength of hybrid materials increase first and then decrease along with the contents of CeO₂-ZrO₂ increasing. Approprite amount of mesoporous particles can optimize the hybrid materials mechanical property and increase the Shore hardness. After introducing“percolation model”, the preliminary mathematical model of blending modified CeO₂-ZrO₂ mesoporous particles into epoxy resin is established and the variation of hybrid materials property with different content mesoporous particles can be explained.更多还原