【作者】 万丽娟；

【导师】 付宏刚；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2008， 博士

【摘要】 本文采用溶剂蒸发诱导自组装（EISA）方法,合成了介孔SiO₂及其复合体材料。并在EISA方法的基础上,设计了有效抑制无机盐的水解速率的氨介质EISA合成路线,制备了Al₂O₃、Fe₂O₃介孔材料,并探讨了合成机制。利用EISA方法制备了介孔二氧化硅SBA-16。在合成有序介孔SiO₂的体系中原位嵌入Eosin Y制备Eosin Y/介孔SiO₂复合体材料。研究表明,随着Eosin Y量的增加,复合体荧光谱峰增强,明显强于纯Esoin Y,这种现象可以归因于Eosin Y分子被锚定在介孔SiO₂的结构中,使Eosin Y分子间的荧光自猝灭效应减弱,从而使Eosin Y/介孔SiO₂复合体的PL谱峰增强。以SBA-16膜/ITO为电极电沉积控制CdS生长在其表面,分析表明生长的CdS粒子形貌为层层包裹的“花状”。利用孔道均一而且孔径小于5 nm的介孔分子筛膜为基底,以阻碍Cd²⁺和S₂O₃^2-向介孔孔道中的扩散,同时阻碍了其在孔道中发生电化学反应,从而控制CdS只生长在电极表面,具有较好的光致发光性质。针对制备有序介孔Al₂O₃材料的方法多使用铝的醇盐作为前驱体,而使用无机盐为前驱体所需反应时间较长、反应速率难于控制的问题,设计了通过NH₃·H₂O与表面活性剂相互作用而抑制无机铝盐的水解速率氨介质EISA合成路线。采用氨介质EISA方法,以AlCl₃·6H₂O为无机前驱体,三嵌段聚合物P123或F127为结构导向剂,合成了具有蠕虫状、二维六方结构的介孔Al₂O₃材料。对于有序的介孔Al₂O₃,将其焙烧温度提高至700 oC,得到γ-Al₂O₃介孔材料,其孔径为7.6 nm,BET测定比表面积为200 m²·g^-1,孔容为0.38 cm³·g^-1,具有二维六方介孔结构。利用氨介质EISA方法,通过改变铝溶胶的陈化时间,在F127-EtOH-NH₃·H₂O-无机盐体系中设计合成了孔结构可控（二维六方和三维面心立方结构）的一系列均一透明的介孔Al₂O₃薄膜材料。所得介孔材料具有窄的孔径分布、较大的比表面积以及高度有序的介孔结构。根据大量的结构表征找出了介孔结构变化的规律,并据此提出了孔结构可调控的机制。和以往报道的合成步骤相比这种合成路线的优势在于能够在短时间内很容易的控制Al₂O₃薄膜的介观相。孔结构可调的介孔Al₂O₃薄膜材料的合成机理为:三嵌段表面活性剂的EO基团与NH₃·H₂O之间的氢键作用使NH₃·H₂O解离速度减慢,NH₃·H₂O缓慢释放使无机物水解速率受到抑制,从而水解为较小的铝氧团簇,适与表面活性剂胶束的组装;EISA方法属于液晶模板机理,挥发性溶剂在一定温度和湿度下缓慢蒸发,使表面活性剂胶束组装成不同结构,再与铝氧团簇间形成较强的相互作用,制备出不同介孔结构的Al₂O₃材料,且模板剂去除后能够保持有序性较好的介孔结构。通过改变焙烧温度,可以得到不同晶相（γ或δ,α-Al₂O₃）的介孔Al₂O₃材料。利用氨介质EISA方法,以三嵌段聚合物F127为结构导向剂,将无机铝源换成无机铁源[Fe（NO₃）₃·9H₂O],合成了蠕虫状α-Fe₂O₃薄膜和粉体材料,样品的粒径为17.36³3.57 nm,BET测定比表面积为20.08⁴5.11 m²·g^-1,薄膜厚度为360.5³70.1 nm。研究表明,随着焙烧温度的升高,样品的晶粒尺寸增加、比表面下降且膜厚增加。探讨了合成机制,说明氨介质EISA方法在抑制无机盐水解速率方面有一定的普适性。对焙烧后的粉体样品进行吸附Cr（VI）离子性能测试,结果表明不同温度下焙烧的样品的移除能力均明显优于商用α-Fe₂O₃。这种更强的移除能力可以归因于蠕虫状α-Fe₂O₃粉体材料具有较高的比表面积以及多孔的结构,为污水处理等领域提供了新材料。更多还原

【Abstract】 Mesoporous silica and complex have been prepared through the EISA method. Based on the EISA method, the NH₃·H₂O-EISA method was designed to control the hydrolysis rate of inorganic salts, through which, Al₂O₃ and Fe₂O₃ mesostructured materials were synthesized and mechanism was discussed.Mesoporous silica SBA-16 was prepared through the EISA method. Eosin Y/mesoporous SiO₂ complex was synthesized through the incorporation of Eosin Y in the system of preparing mesoporous silica. The results show that PL intensity of complex increase with the increase of Eosin Y and is much stronger than that of pure Eosin Y, which is attributed to decrease of the PL self-abruptly effect vanishing by the Eosin Y anchored in mesoporous silica structure. CdS with flower-like morphology was synthesized through the electro-deposition on the SBA-16 film/ITO substrate. Cd2+ and S₂O₃^2- could not diffuse into the mesopore and have reaction because the mesopore are less than 5 nm. CdS was grown on the surface of electrode with good PL property.For the preparation of ordered mesoporous Al₂O₃, aluminum alcoxides were often used as inorganic precursors, while inorganic salts were used as precursors. Long reaction time was needed and the hydrolysis rate was difficult to control. The NH₃·H₂O-EISA method was designed to control the hydrolysis rate. Mesoporous alumina materials with wormhole-like or 2D hexagonal mesopore structures have been synthesized using AlCl3·6H₂O as inorganic precursor and tri-block copolymer P123 or F127 as structure-directing agent through the designed NH₃·H₂O-EISA method. The results show thatγ-Al₂O₃ mesoporous material with 2D hexagonal mesopore structure and narrow pore size distribution has been obtained when calcination temperature is raised to 700 oC. The pore size is 7.6 nm, BET surface area is 200 m²·g^-1 and pore volume is 0.38 cm³·g^-1.Uniform and transparent mesoporous alumina thin film with tunable mesopore structures （2D hexagonal and 3D Fm3m cubic） have been synthesized in F127-EtOH-NH₃·H₂O-salts （EsNs） system by changing the aging time of the sol through the NH₃·H₂O-EISA method. Mesoporous materials have narrow pore size distribution, relatively large BET surface area and highly ordered mesopore structures. According to the results of experiments, the rule of mesopore structures’change was found and formation mechanism of ordered mesoporous alumina thin films with tunable mesopore structures is proposed. The ability to easily control the mesophases of alumina layers within a short time provides distinct advantages over previously reported synthesis procedures. In our strategy, formation mechanism of the synthesized mesoporous alumina thin films with tunable mesopore structures was summarized as follows: Hydrogen bond may be formed between EO of surfactant and NH₃·H₂O, which controls the dissociation rate of NH₃·H₂O. The hydrolysis of inorganic precursors can be controlled to provide relatively smaller aluminum oxo-clusters, which offer probability for assembly with surfactants; The EISA method belongs to LC template mechanism and volatile solvents evaporate at some temprerature and relative humidity, which makes the micelles assemble to different structures and surfactant can have assembly with aluminum oxo-clusters to form different mesostructures; There is strong interaction between surfactant and aluminum oxo-clusters which makes mesophase keep with removal of surfactant. Mesoporousγorα,δ-Al₂O₃ can be obtained through changing calcination temperature.Using the NH₃·H₂O-EISA method, Fe（NO3）3·9H₂O instead of aluminum inorganic salts as inorganic precursor and F127 as structure-directing agent, wormlikeα-Fe₂O₃ were synthesized. The particle size is 17.36³3.57 nm, BET surface area is 20.08⁴5.11 m²·g^-1 and film thickness is 360.5³70.1 nm The study shows that crystalline particle size of samples increases, BET surface area decreases and film thickness increases with the increase of calcined temperature. The formation mechanism was discussed. The study shows the NH₃·H₂O-EISA method has general application in controlling hydrolysis rate of inorganic salts. The samples under different calcined temperature were tested to remove heavy metal ion [Cr （VI）]. The removal capacity of samples is 4.30⁵.03 mg·g（Cat.）^-1,which was better than that of commercialα-Fe₂O₃ [0.70 mg·g（Cat.）^-1]. The better performances are attributed to relatively higher surface area and porous structure of wormlikeα-Fe₂O₃, which provide novel materials in water treatment.更多还原