【作者】 宗洁；

【导师】 朱以华；

【作者基本信息】 华东理工大学 ， 材料科学与工程， 2013， 博士

【摘要】 由于介孔二氧化硅(MS)微球比表面积大、孔体积大、孔径可调、表面可官能团化、稳定性好、生物相容性好,在吸附与分离、主客体组装等领域有着广泛的应用前景,而这些离不开MS微球的功能化。而根据性能要求,设计基于MS微球的纳米反应器来完成其对纳米材料的组装,形成介孔杂化材料,是目前对MS进行功能化的一个非常有效的途径,其中MS微球的孔径是影响纳米反应器性能的一个关键因素。不同孔径的MS微球通过尺寸选择效应对带电的不同尺寸的纳米客体材料进行选择性地组装。此外,层层自组装技术也是一种可以用于限域反应的有效手段。本课题设计了四种基于MS微球的纳米反应器,并结合层层自组装技术,将不同种类的纳米材料组装上去,形成具有催化、光电响应、荧光等不同性质的复合微球,并考察了其相应的性能以及在不同领域的应用。1.本文第二章以十六胺为模板、氨水为催化剂、正硅酸乙酯(TEOS)为前驱体,制备了平均粒径为1.3pm的MS微球,通过复盐浸渍、高温焙烧法调节MS微球的介孔孔径,并考察了焙烧温度和气氛对孔径的影响,有效地制备了具有不同孔径且形貌规整的MS微球,其孔径可从3.2nm调节至46.8nm。该方法简单易行,为纳米反应器的构筑奠定了基础。2.本文第三章利用MS微球和Au纳米颗粒或脲酶之间的静电吸附作用,制备了MS/Au或者MS/脲酶复合微球。结果表明,随着不同孔径的MS微球对Au纳米颗粒负载程度的增加,Au纳米颗粒在组装过程中的团聚程度不同,溶液由原来的红色逐渐变为紫色,当负载程度最大时,溶液变为蓝紫色：基于这种选择尺寸效应,设计了基于MS微球的纳米反应器,使脲酶在MS孔道内催化尿素水解,随着MS微球对脲酶负载程度的增加,其催化效果也逐渐提高。3.鉴于金属氧化物纳米颗粒的催化性能,结合层层自组装技术和高温焙烧法,本文第四章设计了基于MS微球的金属氧化物纳米反应器,使金属离子在其孔道内与尿素分解的产物发生反应,生成碱式碳酸盐,再通过高温焙烧,成功地将结晶性良好的金属氧化物(CuO、NiO或C0304)纳米颗粒组装到MS微球上,形成的复合微球保持了球形形貌,单分散性良好,且仍为介孔结构,有利于提高其催化性能。该方法可用于制备含有其他金属氧化物纳米颗粒的介孔杂化材料。此外,所制备的复合微球具有较大的氧化还原峰面积,从而具有较多的催化活性位点。4.鉴于CuO和FeS2的光电性能,结合层层自组装技术和溶剂热法,本文第五章设计了基于MS微球的金属氧化物@金属硫化物纳米反应器,一方面使Cu2+在其孔道内与尿素分解的产物发生反应,另一方面使Fe3+经过硫代硫酸钠的还原作用,在溶剂热条件下实现CuO在介孔孔道和FeS2在MS微球表面的组装,制备而得的MS@CuO@FeS2复合微球呈球状,表面具有片层结构,能够吸收紫外到近红外范围内的光,具有光电响应性能。此外,得到的MS@CuO@FeS2复合微球还具有磁性能,将其与PVA凝胶组装成各向异性膜,可以提高太阳能电池的性能。5.鉴于碳量子点(CDs)的生物相容性及荧光性能,本文第六章设计了基于MS微球的CDs的纳米反应器,使CDs在其孔道内限域生长,用NaOH刻蚀Si02,释放得到的CDs,具有波长依赖和上转换荧光特性,其稳定性、水溶性以及生物相容性良好。增大MS微球的孔径或者前驱体的用量,CDs的粒径也会相应增加。将CDs用于检测Cu2+和L-半胱氨酸(L-Cys), Cu2+的加入引起了荧光淬灭,L-Cys对Cu2+的竞争反应,又使荧光得到恢复。该方法简单、响应速度快、成本低、环境友好、选择性且灵敏度高,Cu2+的检测限为2.3x10-8M,而L-Cys的检测限可达3.4×10-10M。此外,通过酰胺化反应用PAMMA连接Au纳米颗粒和CDs,形成了Au-PAMAM-CDs复合物,有效地增强了CDs的荧光。研究了Au纳米颗粒或者CDs的用量对荧光增强效果的影响,在优化条件下,荧光增强效果达到了62倍。更多还原

【Abstract】 Mesoporous silica spheres have opened up many possibilities for applications in absorption and separation, and host-guest assembly, due to their large surface areas, large pore volume, controllable pore size, easy surface-functionalization, good stability and biocompatibility. However, it can’t work without the functionalization of mesoporous silica spheres. An effective way of the functionalization of mesoporous silica spheres is the fabrication of mesoporous silica sphere-based nanorectors to assemble nanomaterials according to the acquirements of properties. It is worth noting that the pore size is one of the important factors to affect the performance of the nanoreactors. Due to the size-selective effect, the charged nanomaterials with different sizes can be assembled on MS spheres with different pore sizes selectively. In addition, layer-by-layer (LbL) assembly technique is also useful for confined reaction. Herein, we fabricated four kinds of mesoporous silica sphere-based nanorectors. With the help of LbL assembly technique, different types of nanoparticles were assembled on the mesoporous silica spheres, forming composite spheres with different properties, such as catalytic, photoelectric, and fluorescent properties. Their properties and applications in different areas were also investigated.1. In Chapter2, MS spheres were firstly prepared with hexadecylamine as surfactant, ammonia as catalyst, and tetraethyl orthosilicate (TEOS) as silica precursor. The size of the resulting MS spheres is ca.1.3μm. In the presence of complex salts, the pores of MS spheres can be controlled by calcination, which retained the spherical morphology. The effect of calcination temperature and atmosphere on the pore size was also investigated. The pores can be enlarged from3.2to46.8nm effectively. This method is simple and feasible, which is the base for the fabrication of nanoreactors.2. In Chapter3, the assembly of Au nanoparticles or urease on MS spheres was carried out through their electrostatic interaction, forming MS/Au composite spheres. The increasing amount of Au nanoparticles assembled on MS sphere lead to their different aggregation. The color of Au colloid was accordingly changed initially from red, then to purple, and finally to violet blue. Similarly, urease with different amount was assembled on MS spheres with different pore sizes. By using MS spheres as nanoreactors, urease loaded on MS spheres can catalyze urea. And the enzymatic activity increased with the increase of the loading amount of urease.3. Considering the excellent catalytic activities of metal oxide nanoparticles, we assembled them on MS spheres using MS spheres as nanorectors with the help of LbL assembly technique in Chapter4. Metal ions absorbed in the pores of MS spheres can react with the product from the hydrolysis of urea. Metal oxides (CuO, NiO, or CO3O4) nanoparticles were then formed in the pores of MS spheres by calcination. The resulting composites are still spherical, monodisperse, and mesoporous, which is favorable to enchance their properties. This method can be expanded to prepare other composites which contain other metal oxides nanoparticles. In addition, the resulting composite spheres have large redox peak area so that they have many catalytic active sites.4. Considering the good photoelectric properties of CuO and FeS2, we assembled them on MS spheres using MS spheres as nanorectors in Chapter5. With the help of LbL assembly technique together with solvothermal method, Cu2+which was absorbed in the pores of MS spheres can react with the product from the hydrolysis of urea, and at the same time Fe3+can react with Na2S2O3, reslting in the successful assembling of CuO and FeS2. The resulting MS@CuO@FeS2composites are spherical, have rough shell with flake-like texture, and can absorb a wide range of light, from UV to near-infrared, making them sensitive to UV light. In addition, they show ferromagnetic properties, which enable them to align in PVA gel. The obtained films were anisotropic and promising for improving the performance of solar cells.5. Considering the excellent biocompatibility and fluorescent properties of CDs, we prepared them on MS spheres using MS spheres as nanorectors in Chapter6. By etching silica with NaOH, CDs can be released. The resulting hydrophilic CDs have good stability, wavelength-dependent and up-converted photoluminescent properties. They are also easily functionalized. The increase of the pore size of MS spheres and the amount of precursor of CDs results in the increase of the size of CDs. CDs were then used as fluorescent probes for the detection of Cu2+and L-cysteine (L-Cys). The addition of Cu2+cations leads to their absorption on the surface of CDs and the significant fluorescence quench of CDs. While the addition of L-Cys reverses the quenching and restore the fluorescence due to its ability to remove Cu2+from the surface of CDs. This method for the detection of Cu2+and L-Cys is facile, rapid, low-cost, environment-friendly, and highly selective and sensitive. The detection limit is2.3×10-8M for Cu2+and3.4×10-10M for L-Cys. In addition, the Au-PAMAM-CDs conjugates were formed by conjugating of Au nanoparticles (Au NPs) and CDs to PAMAM dendrimers through an amidation reaction. This makes Au NPs and CDs in an appropriate distance for the fluorescence enhancementdue to the strong local electric fields created by Au NPs surface plasmon resonance. Varying the amount of Au NPs or CDs in the system can affect the fluorescence enhancement. The results showed a62-fold enhancement for CDs was achieved.更多还原