【作者】 崔鹏；

【导师】 苑世领；

【作者基本信息】 山东大学 ， 物理化学， 2008， 硕士

【摘要】 本文主要对功能性二氧化硅微纳米材料的制备与性质进行了研究,获得一些创新性结果。这些研究对硅材料的合成与应用,以及玉米植株的合理开发提供了良好的途径。1.植硅石与玉米植株中的硅植硅石是沉淀于某些高等植物体内（细胞壁、细胞腔内部或细胞之间的间隙）的含水非晶态二氧化硅。许多资料显示,禾本科植物中含有较多的硅,玉米植株是禾本科植物的典型代表。因此,这里重点研究了玉米（秆、叶片、根）中的植硅石。并深入讨论了直接燃烧法、酸处理法、酸碱处理法、酶处理法对玉米植株中植硅石的影响。发现直接燃烧法在500℃燃烧8h可以获得形貌较为完整的植硅石;酸处理法获得了纳米级的硅球,并对不同的酸处理结果做了对比,发现在400℃硝酸处理2h的反应条件最佳,得到了粒径200nm的硅球;样品经酶处理后,发现酶对植硅石影响不大,但比较严重的影响了纤维素、半纤维素、木质素的形貌和结构。对样品分别进行了显微镜、透射电镜、扫描电镜、红外光谱、X射线衍射、电子能谱等分析。最后,推测了玉米植株中硅的来源与反应状况,推测了玉米植株内微米级硅球转化为纳米级硅球的过程。2.SiO₂微孔材料的制备按照国际纯粹和应用化学联合会（IUPAC）的定义,多孔材料孔径在2-50nm之间的材料称之为介孔材料,低于2nm称为微孔材料。超微孔材料一般是指其孔径介于微孔和介孔临界区间即在1.0-2.0nm范围内的孔材料,其合成思路、材料性质与介孔材料相似。介孔材料的制备多以表面活性剂的自组装体系为模板,通过溶胶-凝胶化学反应来完成的。在催化剂、催化剂载体、色谱填充材料、吸附与分离技术、环保、主客体化学、材料合成模板等领域具有广泛的应用前景。本文以三种不同的小分子水凝胶（Fmoc-D-丙氨酸-D-丙氨酸二肽、Fmoc-D-丙氨酸-L-苏氨酸二肽、Fmoc-D-丙氨酸-L-酪氨酸二肽）为模板合成了超微孔二氧化硅材料,并且利用紫外光谱、红外光谱、X射线衍射、N₂吸附一脱附、透射电镜、高分辨透射电镜等技术对合成材料进行了表征。结果显示其孔径在1.0-2.0nm之间,其范围在超微孔材料范围内。其中,最大的BET比表面积达880.353m²/g。3.纳米SiO₂粒子的改性及SiO₂-Ag异二聚体的形成由TEOS、A-151和KH570合成了改性的纳米二氧化硅,改性后的纳米二氧化硅具有较好的疏水性。对改性前后的纳米二氧化硅表面进行表征,证明了该实验方法可以有效的分散其聚集体。由XRD分析证明改性前后硅球的状态都是无定形态;而FTIR测试证明A-151和KH570确实已经和纳米二氧化硅表面的羟基发生了化学反应;TEM测试证明了改性后的纳米二氧化硅达到了纳米级的分散。除此之外,我们还分别用亲水、疏水两种硅球合成了SiO₂-Ag的异二聚体。发现,对于亲水的硅球而言,小粒径的硅球更容易形成异二聚体,大粒径的硅球则容易形成纳米复合微球。而对疏水的硅球来讲,低温时的反应更容易获得SiO₂-Ag异二聚体。所有的实验结果由TEM来证明。本论文的新颖之处:1.本论文主要研究了玉米植株中植硅石的存在、来源和形貌,对比了直接燃烧、三种常见酸、酸和碱、三种混合酶对玉米植株中纤维素、半纤维素、木质素、植硅石形貌的影响。并对微米级的植硅石进行破坏得到了纳米级的硅球。2.用一种新颖的模板剂——小分子水凝胶（包括Fmoc-D-丙氨酸-D-丙氨酸二肽、Fmoc-D-丙氨酸-L-苏氨酸二肽、Fmoc-D-丙氨酸-L-酪氨酸二肽）合成了具有较高比表面积的二氧化硅超微孔材料,并用溶剂洗涤法去除了模板剂。3.用常见的溶胶-凝胶法,调节合适的酸度,用正硅酸已酯直接与硅烷偶联剂反应获得了粒径约100nm的亲油的二氧化硅粒子。用超声波法用亲水、亲油两种不同的硅球合成了SiO₂-Ag的异二聚体和纳米复合微球。更多还原

【Abstract】 The synthesis and properties of functional silicon dioxide micro-nanometer materials were studied.These studies on Phytoliths,super-microporous silica and heterodimers of SiO₂-Ag nanoparticles are helpful to synthesis and application of silica materisals,and can provide a potential application for zea mays and others.1.Phytoliths and silica in zea maysPhytoliths,opal phytoliths,or plant opal,are minute biogenic structures of silica that’s deposited,depending on the species of plant,between the cells,within the cell walls,or even sometimes completely infilling the cells themselves.It is known that there are lots of silica in gramineous plants,in this paper phytoliths in its stalk,leaf and root of zea mays were focused on.The morphology of phytoliths were studied in different conditions such as under the combustion,in acid（hydrochioride,sulfate,nitric acid）soulution,through acid and alkali method,and using the enzyme（mixture）.Firstly,the combustion in 500℃can give the morphology of phytoliths in the micro-meter level;then silica nanoparticles in the nano-meter level were obtained in different acid solution.We found that the best process is in the nitric acid solution,and the nano-silica obtained have the diameter of 200nm.When the enzyme was used to treat the plant,the phytoliths is not affected,but the cellulose,hemicellulose,hemicellulose,lignin in zea mays can be decomposed,and their morphology were destroyed.At last,these silica materials formed in different experiments were characterized by microscope,TEM, SEM,FTIR,XRD,EDS etc.2.Synthesis of super-microporous silica materialsAccording to the definition,porous materials can be divided into three types depending on their pore size（diameter,d）,micro-（d＜2nm）,meso-（2nm＜d＜50nm）, and macroporous materials（d＞50nm）.In this section,super-microporous materials with smaller pores of 1.0-2.0nm were discussed.Mesoporous materials are usually synthesized templated by self-assembly of surfactants through sol-gol chemistry process,but in recent years,small biological molecules as a new falmily of template have been reported more and more.Several small-molecular hydrogels（Fmoc-D-Ala-D-Ala-OH,Fmoc-D-Ala-L-Tyr-OH, Fmoc-D-Ala-L-Thr-OH）are considered as the templates to synthesize the super-microporous silica,and they were characterized by different techniques such as Ultraviolet spectrophotometry（UV）,fourier transform IntraRed（FTIR）,X-ray diffraction（XRD）,TEM,HRTEM,Nitrogen adsorption-desorption technique.The results showed that the pore diameter was between 1.0-2.0nm,which is in the range of super-micropores materials.And the maximum of BET specific surface area above 880.353m²/g.3.Modification of SiO₂ and synthesis of heterodimers of SiO₂-Ag nanoparticlesIn this section,nano-silica were synthesized by TEOS and silane coupling agent（A-151 and KH570）have good hydrophobic property.The surface morpholgy of nano-silica before and after modification was studied.It is verified that modification of nano-silica can be carried out through this method.The analysis of FTIR proved that the A-151 and KH570 has been successfully grafted on the surface of nano-silica. Analysis of XRD proved that nano-silica have the amorphous structure.TEM showed that the modified nano-silica can be dispersed in organic reagent such as ethylalcohol etc.In addition,the heterodimers of SiO₂-Ag nanoparticles were synthesized on hydrophilic and hydrophobic surface of nano-silica.On hydrophilic surface,the smaller nanoparticle can form the heterodimers easily,however,the bigger particles normally form multimers.On hydrophobic surface,the dimers can be formed in the low temperature.The innovations in the thesis are as follows:1.This paper focued on the phytoliths in zea mays,and the morphology of phytoliths were studied after combustion,in acid（hydrochloride,sulfate,nitric acid） soulution,through acid and alkali method,and using the enzyme（mixture）.Finally, the silica nanoparticles were investigated through the phytoliths.2.Some small-molecular hydrogels（incloud Fmoc-D-Ala-D-Ala-OH,Fmoc-D-Ala -L-Tyr-OH,Fmoc-D-Ala-L-Thr-OH）were used as the new templates to synthesize the super-microporous silica materials.3.Through the simply method,silica nanoparticles were synthesized directly by TEOS and silane coupling agents.The heterodimers of SiO₂-Ag nanoparticles were synthesized on the hydrophilic and hydrophobic SiO₂ nanoparticles.更多还原