Preparation Of Mesoporous Cerium-Zirconium Mixed Oxide-Polymer Hybrid Materials And Its Mechanical Property

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 (?-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 (?-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.