以嵌段共聚物为模板的介孔材料的合成与调控
文献类型：学位论文
| 作者 | 羊彬 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007-06-11 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 刘会洲 |
| 关键词 | 嵌段共聚物 介孔材料 自组装 酸效应 混合模板 调控合成 |
| 其他题名 | Controllable Synthesis of Mesoporous Materials Templated by Triblock Copolymer |
| 学位专业 | 无机化学 |
| 中文摘要 | 介孔材料的发展日新月异，新结构和新形貌层出不穷。但是，对于大部分的介孔材料，由于作为模板的表面活性剂种类复杂,合成步骤较多,条件控制因素多,使得材料合成缺乏规律性、系统性和可循机制，在一定程度上限制了介孔材料的发展，可控合成介孔材料仍有重要的理论和现实意义。 本文以嵌段共聚物为模板剂，进一步探索嵌段共聚物聚集的调控机理，通过调控嵌段共聚物的自组装性质来制备新型介孔材料。研究内容包括以下三个方面： （1）盐酸对嵌段共聚物聚集的影响。 通过傅立叶变换红外光谱、荧光光谱、透射电镜、粒径分析仪研究了盐酸对嵌段共聚物聚集行为的影响。盐酸可以使醚氧基和质子化的水分子之间的氢键得到加强，从而使得嵌段共聚物的临界胶团温度CMT增大。在低盐酸浓度下，胶团的尺寸因PEO链段的伸展而增大，粒度分布也因同种电荷相斥而趋于均一。在盐酸浓度高达3M时，质子化的水分子通过氢键架桥连接各胶团而形成大聚集块。 （2）以嵌段共聚物为模板合成介孔材料中的酸效应。 在不同酸环境中，孔径随酸根离子疏水性增强而增大；酸种类对材料形貌产生了影响。因为硝酸根的阴离子半径最小，其与硅酸根结合能力最强，所以硅酸离子与模板剂结合后在硝酸条件下缩合最快，形成的表面活性剂胶束最长；当硝酸的浓度达到2M时，硅酸水解的速度太快，相分离时间远大于溶胶-凝胶转换时间，使得硅酸酯直接水解沉淀，生成无定形材料。 盐酸浓度的不断增加使胶团的亲水性增加，材料的孔径随之减小；盐酸浓度对材料形貌也产生了影响。 酸种类以及浓度并不影响材料二维六方的介孔孔道结构。 （3）以阴离子表面活性剂SDS与嵌段共聚物为混合模板制备具有高级结构的介孔材料。 以嵌段共聚物P123与阴离子表面活性剂SDS混合模板导向合成了高度有序的体心立方结构材料。用传统表面活性剂的有效体积堆积参数g值的变化分析了材料孔结构由二维六方结构向体心立方结构的转变。 以嵌段共聚物P103和阴离子表面活性剂SDS为混合模板，在盐溶液中导向合成了纳米级到微米级介孔氧化硅空心球，材料形貌规整可调，介孔孔道为三维蠕虫状无序结构。增加盐含量，可以调控得到多壳介孔氧化硅空心球。改变嵌段共聚物和阴离子表面活性剂的浓度比，可以调控介孔氧化硅空心球的大小和壁厚。通过研究混合表面活性剂体系在盐溶液和非盐溶液中的聚集状态，提出了双模板机理。 |
| 英文摘要 | Synthesis of mesoporous materials is undergoing a tremendous development recently; new structures and new morphologies are emerging rapidly. However, the synthesis mechanism is still not fully understood due to the various types of surfactants, the complicate synthesis processes as well as different synthesis conditions that contribute, to some extent, in limiting the development of mesoporous materials. The controllable synthesis of mesoporous materials is still desired due to its theoretical and practical significance. Based on the research experience of aggregation and self-assembly property of triblock copolymer accumulated for many years in our lab. This thesis aims to study the triblock copolymer templated mesoporous materials synthesis by controlling the self-assembly property of triblock copolymer. The main contents are as follows: （1） Hydrochloric acid effect towards the aggregation property of triblock copolymer. Effect of hydrochloric acid on the aggregation of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) block copolymers was investigated by transmission electron microscopy (TEM), particle size analyzer (PSA), Fourier transformed infrared, and fluorescence spectroscopy. The Critical Micellization Temperature (CMT) for triblock copolymer in different hydrochloric acid aqueous solutions increases with the increase of acid concentration because of the enhanced hydrogen bond between alkyl group and protonated water molecules. When the hydrochloric acid concentration is low, TEM and PSA showed an increase of the mean micelle diameter and the decrease of the micelle polydispersity at room temperature, which demonstrate the extension of EO corona and tendency of uniform micelle size because of the charge repulsion. While under strong hydrochloric acid conditions, the micelles aggregate through the protonated water bridges. （2）Acid effects towards the synthesis of mesoporous materials templated by triblock copolymer. When synthesized under different kinds of acids, the pore diameter of mesoporous materials increased in the following sequence: nitric acid, hydrochloric acid, sulfuric acid, because of the increase of hydrophobic properties; Acid species play an important role towards the material morphology. The radius of anion determines the binding ability between the silicate and surfactant, the highest rate of condensation speed was observed when nitric acid was used, resulting in the longest micelle rods; however, under a high nitric acid circumstance, silicate hydrolyze very quickly and deposit directly since the phase separation time is shorter than the sol-gel transition time, it resulted in an amorphous morphology. With an increasing hydrochloric acid concentration, the pore diameter decreased. Acid species and acid concentration don’t affect the two-dimension hexagonal pore structure. （3）Controllable synthesis of mesoporous materials with hierarchical structure templated by anionic surfactants (SDS) and triblock copolymer. Mesoporous material with Ia3d structure was successfully prepared by mixing block copolymer P123 and anionic sodium dodecyl sulfate (SDS) as structure – directing agents. The structure transition from two dimension hexagonal to body centre cubic has been explained as a change in packing parameter g. Nanometer to micrometer diameter mesoporous silica hollow spheres with controllable hierarchical morphologies were developed by an anion-nonionic surfactant-salt system. Good morphology and big permeable three-dimension wormlike mesoporous pore of the shell were obtained and can be well controlled by adjusting salt concentration. The size and wall thickness of mesoporous silica hollow sphere could also be controlled by changing the molar-rate of the anion/nonionic surfactant. A new bi-template formation mechanism has also been proposed by investigating the salt effect towards the anionic-nonionic surfactants system. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 106 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1164]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 羊彬. 以嵌段共聚物为模板的介孔材料的合成与调控[D]. 过程工程研究所. 中国科学院过程工程研究所. 2007. |
入库方式： OAI收割
来源：过程工程研究所
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