【作者】 田燕；

【导师】 王琪珑； 崔得良；

【作者基本信息】 山东大学 ， 无机化学， 2008， 博士

【摘要】 在本文中，我们利用溶剂热压方法，以TiO₂纳米粉作为原料，采用两种不同方法制备了PMMA／TiO₂复合多孔纳米固体，通过热处理成功地获得了孔径大小均一且在空间均匀分布的TiO₂多孔纳米固体；以不同的聚合物凝胶作为模板，用溶剂热压法成功地制备了具有不同比表面积和孔容的TiO₂多孔纳米固体。为了改善样品中孔径分布的均匀性，我们又以PVP-K30水溶液作为造孔剂，以TiO₂和ZnO纳米颗粒作为原料，制备了TiO₂和ZnO多孔纳米固体。对多孔纳米固体材料的性能进行了表征，并初步解释了复合材料性质的变化规律。首先，以甲基丙烯酸甲酯（MMA）作单体，以过硫酸铵为引发剂，通过溶液聚合制备了PMMA／TiO₂复合多孔纳米固体。实验结果表明：在改变单体的用量时，得到的PMMA／TiO₂复合多孔纳米固体的主孔径基本上都分布在5-25 nm范围内，但是孔径均匀性、比表面积以及孔容均存在明显的差异。当MMA／TiO₂纳米粉的重量比为1：19时，PMMA／TiO₂复合多孔纳米固体的孔径分布均匀，比表面积和孔容分别为127．20 m²／g和0．27 cm³/。另外，我们直接以聚甲基丙烯酸甲酯超细粉作原料，以去离子水为造孔剂，制备了PMMA／TiO₂复合多孔纳米固体，并对其性质进行了测试分析。实验结果表明：在固体组分总量固定且造孔剂用量相同的情况下，通过改变PMMA的用量，可以在一定范围内调变多孔纳米固体的孔径分布、比表面积和孔容。其中，PMMA／TiO₂纳米粉的重量比为1：9时，制备的复合多孔纳米固体平均孔径明显减小，为8．77 nm；当PMMA／TiO₂纳米粉的重量比为2：3时，得到的PMMA／TiO₂复合纳米固体是实心块体，样品内没有孔道；其他重量比条件下制备的复合多孔纳米固体的平均孔径均有不同程度的增大，而比表面积和孔容则随着PMMA／TiO₂纳米粉的重量比的增大而明显降低。PMMA／TiO₂复合多孔纳米固体均具有较大的抗压强度，而且当PMMA／TiO₂纳米粉的重量比改变时，复合多孔纳米固体的介电常数也有明显差异，随着PMMA／TiO₂纳米粉重量比的增大，复合多孔纳米固体的介电常数先升高后降低，PMMA／TiO₂纳米粉的重量比为1：19时介电常数最大，为11．44。为了制备孔径分布均匀的TiO₂多孔纳米固体，我们将上面制备的PMMA／TiO₂复合多孔纳米固体进行热处理。实验结果表明，热处理后TiO₂纳米颗粒的物相稳定，粒度没有明显的变化，TiO₂多孔纳米固体孔道中没有PMMA残留，而且TiO₂多孔纳米固体具有很高的热稳定性。在原料固体组分总量固定且造孔剂用量相同的情况下，尽管制备时PMMA的用量不同，TiO₂多孔纳米固体的平均孔径、比表面积和孔容变化较小，当PMMA／TiO₂纳米粉的重量比为1：9时平均孔径最大，为10．44nm：与不加PMMA的样品相比，其他重量比条件下制备的多孔纳米固体的孔容均有不同程度的减小。随着PMMA／TiO₂纳米粉比值的增大，多孔纳米固体的抗压强度先升高后降低，当PMMA／TiO₂纳米粉的重量比为1：9时，TiO₂多孔纳米固体的抗压强度最大，为242．8 MPa。另外，PMMA／TiO₂纳米粉的重量比不同，复合多孔纳米固体的介电常数也有明显差异，随着PMMA／TiO₂纳米粉重量比的增大，多孔纳米固体的介电常数先升高后降低，PMMA／TiO₂纳米粉的重量比为1：4时介电常数最大，为14．08。因此我们在实际应用中，通过改变PMMA的用量，可以在一定范围内调变多孔纳米固体的抗压强度及介电常数，制备既具有较大的抗压强度，又具有一定平均孔径、比表面积、孔容和介电常数的TiO₂多孔纳米固体。我们又以聚合物作为模板，尝试控制TiO₂多孔纳米固体的孔道分布。分别以丙烯酸丁酯（BA）和苯乙烯作单体，过硫酸铵作为引发剂，通过自由基聚合分别得到了二者的聚合物凝胶。以其聚合物凝胶作模板，TiO₂纳米粉为原料，利用液态溶剂热压方法和煅烧去除模板方法相结合，制备了TiO₂多孔纳米固体。结果表明，在改变单体的用量时，得到的TiO₂多孔纳米固体样品的主孔径基本上都分布在5-35 nm范围内。当BA／TiO₂纳米粉的重量比为1：9时，TiO₂多孔纳米固体的孔径分布均匀，孔容为0．32 cm³/g，此时比表面积最大，达到了87．94m²／g；而当苯乙烯／TiO₂纳米粉的重量比为1：9时，TiO₂多孔纳米固体的比表面积达到174．17 m²／g，孔容达到0．34 cm³／g。为了进一步改善样品中孔径分布的均匀性，我们以非离子型表面活性剂PVP-K30的水溶液作为造孔剂、以TiO₂和ZnO纳米颗粒作为原料，分别制备了TiO₂和ZnO多孔纳米固体。从实验中我们发现：加入少量PVP-K30后TiO₂和ZnO多孔纳米固体的平均孔径增大，增加PVP-K30的量，则平均孔径和孔容又随之减小。溶剂热压过程中多孔纳米固体孔道内有少量PVP-K30残留。将多孔纳米固体进行热处理之后，比表面积变化不大，而平均孔径和孔容明显增大：当PVP-K30／TiO₂纳米粉的重量比为1：9时，平均孔径和孔容分别是14．20 nm和0．23cm³／g。更多还原

【Abstract】 Using TiO₂ nanoparticles as the starting material, PMMA/TiO₂ composite porous nanosolids have been prepared by a novel solvothermal hot-press （STHP） method for the first time. TiO₂ bulk porous nanosolids were prepared from the above composite materials, from which PMMA is removed by calcination. In addition, polymer gel was introduced template as to improve the pore diameter uniformity of the TiO₂ bulk porous nanosolid. TiO₂ and ZnO bulk porous nanosolids were prepared by STHP method using TiO₂ or ZnO nanoparticles with polyvinyl pyrrolidone （PVP-K30） water solution as pore-forming agents. Besides, the properties of these composite materials have been characterized.Firstly, PMMA/TiO₂ composite porous nanosolids have been prepared by polymerization of methyl methacrylate with deionized water as pore-forming agents, and the properties of these composite materials are investigated. The results indicate that, with the increasing amount of MMA, the main pore diameter of the composite materials distributes in the reigon of 5-25 nm, but their pore uniformity, specific surface area and pore volume changed obviously. While the weight ratio of MMA to TiO₂ nanoparticles is 1:19, the specific surface area and pore volume of the PMMA/TiO₂ composite materials are 127.20 m²/g and 0.27 cm³/g, respectively.PMMA/TiO₂ composite porous nanosolids have also been prepared using polymethyl methacrylate as raw material, and the properties of these composite materials are characterized. The results indicate that, the average pore diameter, specific surface area and pore volume of these composite materials can be adjusted by changing the amount of PMMA. The average pore diameter of PMMA/TiO₂ composite porous nanosolids is 8.77 nm and obviously decreases when the weight ratio of PMMA to TiO₂ nanoparticles is 1:9. The average pore diameter, specific surface area and pore volume of PMMA/TiO₂ composite are all zero when the weight ratio of PMMA to TiO₂ nanoparticles is 2:3. The specific surface area and pore volume of these composite materials decrease gradually with the increasing weight ratio of PMMA to TiO₂ nanoparticles. All these PMMA/TiO₂ composite porous nanosolids have high compressive strength, and the dielectric constant of PMMA/TiO₂ composite porous nanosolids also changes obviously with different weight ratio of PMMA to TiO₂ nanoparticles. When the weight ratio of PMMA to TiO₂ nanoparticles is 1:19, the dielectric constant of PMMA/TiO₂ composite porous nanosolids reaches the maximum value, i.e. 11.44 and then decreases gradually with the increasing weight ratio of PMMA to TiO₂ nanoparticles.In order to improve the uniforminty of pore diameter, TiO₂ bulk porous nanosolids were prepared from the above composite materials by removing PMMA through a calcination process. The results indicate that, TiO₂ nanoparticles have not undergone any phase transformation or changing in particle size during the process of calcinations and PMMA has been removed completely from the pore or channels. At the same time, TiO₂ bulk porous nanosolids have high thermal stability both in N₂ and air. The average pore diameter, specific surface area and pore volume of TiO₂ bulk porous nanosolids varies slightly with the increasing weight ratio of PMMA to TiO₂ nanoparticles. When the weight ratio of PMMA to TiO₂ nanoparticles is 1:9, TiO₂ bulk porous nanosolids have the widest pore diameter and the lowest specific surface area, namely, 10.44 nm and 51.1720 m²/g, respectively. Compared with TiO₂ bulk porous nanosolids prepared without PMMA, the pore volume of TiO₂ bulky porous nanosolids decreases in various grades. With the increasing weight ratio of PMMA to TiO₂ nanoparticles, the compressive strength of TiO₂ porous nanosolids increases at the beginning and reaches the maximum value, 242.8 MPa, which is much higher than that of TiO₂/PMMA composite porous nanosolids while the weight ratio of PMMA to TiO₂ nanoparticles is 1:9, then decreases gradually. With the increasing weight ratio of PMMA to TiO₂ nanoparticles, dielectric constant of TiO₂ porous nanosolids increases at the beginning and reaches the maximum value, 14.08 when the weight ratio of PMMA to TiO₂ nanoparticles is 1:4, then decreases gradually. Therefore, the average pore diameter, specific surface area, pore volume, compressive strength and dielectric constant of TiO₂ porous nanosolids could be adjusted by changing the weight ratio of PMMA to TiO₂ nanoparticles.In order to further improve the uniformity of the pores, polymer is used as the template to prepare TiO₂ bulk porous nanosolid. Butyl acrylate （BA） and styrene reacts to form polymer using ammonium persulfate as initiator. TiO₂ bulk porous nanosolid has been prepared using the polymer as template by the STHP method. The main pore size of these nanosolids is 5-35 nm although the weight ratio of monomer to TiO₂ nanoparticles is different, but their pore uniformity, surface area and pore volume changes in various grades. The results indicate that when the weight ratio of BA monomer to TiO₂ nanoparticles is 1:9, the TiO₂ porous nanosolid is obtained with good pore diameter uniformity, its pore volume is 0.32 cm³/g, and surface area reaches the maximum value, 87.94 m²/g. When the weight ratio of styrene monomer to TiO₂ nanoparticles is 1:9, the TiO₂ porous nanosolid is prepared with the highest surface area, namely, 174.17 m²/g, and its pore volume is 0.34 cm³/g.Non-ionic surfactant PVP-K30 solution was used as pore-forming agent to prepare TiO₂ and ZnO bulky porous nanosolids. The pore structure of the TiO₂ and ZnO bulk porous nanosolid is different while the PVP-K30 solution concentration varies. The results indicate that, compared with deionized water, the average pore diameter is obviously enlarged when PVP-K30 solution is used as pore-forming agent. TiO₂ and ZnO bulk porous nanosolids with good pore diameter uniformity, high surface area and pore volume have been successfully prepared by controlling the PVP-K30 solution concentration. With the increase of the amount of PVP-K30, the average pore diameter and pore volume decrease correspondingly. Part of PVP-K30 residue in the channels of TiO₂ porous nanosolids, and they can be removed by heat-treatment. The average pore diameter and pore volume increase obviously and the specific surface area changes very little when the materials have been treated at high temperature. When the weight ratio of PVP-K30 to TiO₂ nanoparticles is 1:9, the average pore diameter and pore volume of TiO₂ porous nanosolids is 14.20 nm, 0.23 cm³/g, respectively.更多还原