以三聚氰胺—甲醛微球为模板制备稀土氧化物空心球的研究

发布时间：2018-08-13 18:19

【摘要】：近年来,具有独特空心结构的空壳材料引起了人们广泛的关注。由于空心球材料的相对密度低、比表面积高、封装能力优良、渗透性良好,在药物载体、生物催化、疾病诊断、光电器件等领域有着广泛的应用。将稀土元素特有的光、电、磁性能与空心结构结合在一起得到的微纳米级稀土氧化物空心球,因此其应用更加广泛。本论文利用甲酸催化水溶液中的三聚氰胺与甲醛反应,制备出表面光滑、粒径分布均一、单分散性良好的三聚氰胺-甲醛(MF)微球。以不同粒径的MF微球为模版,采用均相沉淀法,制备出不同粒径的氧化钇(Y_2O_3)、氧化钆(Gd_2O_3)以及氧化镱(Yb_2O_3)空心球,研究了模板粒径和稀土硝酸盐用量对MF/RE(OH)CO_3(RE=Y,Gd,Yb)复合微球形貌的影响。采用傅里叶红外光谱(FT-IR)、热失重(TG)分析、X射线衍射分析(XRD)、激光粒度(LPA)分析、X射线光电子光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电镜(TEM)等对产物微球进行表征。主要研究内容和结果如下:1.研究了甲酸用量对MF微球形貌及粒径分布的影响。甲酸用量在0.01-0.3 mL范围内时,MF微球的粒径随甲酸用量的增加而减小,其粒径多分散系数呈现先减小后增大的趋势,MF微球的粒径呈正态分布。甲酸用量为0.4 mL时制备出的MF微球粒径不均一。甲酸用量为0.5 mL时,未得到MF微球。当甲酸用量为0.03 mL时,MF微球的粒径为2μm,多分散系数最小为0.129,单分散性最好。研究了甲酸用量与体系反应速率的关系。在0.01-0.06 mL范围内,随甲酸用量增加,体系的反应时间迅速缩短,反应速率加快。当甲酸用量大于0.06 mL时,随甲酸用量增加,体系的反应时间减少的趋势变缓,反应速率趋于恒定。2.以粒径2μm的MF微球为模板,尿素为沉淀剂,六水硝酸钇为原料,制备出粒径为2.2μm,核壳结构MF/Y(OH)CO_3复合微球。煅烧除去模板,得到粒径为1.6μm、球形度良好的Y_2O_3空心球。XRD结果表明制备出的Y_2O_3空心球为立方相。研究了六水合硝酸钇用量对复合微球形貌的影响,确定了最佳包覆工艺。模板用量为0.2 g,六水合硝酸钇用量为0.8 mmol时,可得最佳包覆效果的核壳结构MF/Y(OH)CO_3复合微球。改变六水合硝酸钇为0.6 mmol、0.8 mmol、1.0 mmol,制备出包覆层厚度不同的MF/Y(OH)CO_3复合微球,煅烧除去模板,得到粒径为1.6μm,壳层厚度分别为100 nm、150 nm、200 nm的Y_2O_3空心球。3.以粒径3μm的MF微球为模板,尿素为沉淀剂,六水硝酸钆为原料,利用均相沉淀法制备出粒径为3.4μm,核壳结构MF/Gd(OH)CO_3复合微球。煅烧除去模板,得到粒径为2.4μm,球形度良好的Gd_2O_3空心球。XRD结果表明制备出的Gd_2O_3空心球为立方相。研究了六水合硝酸钆用量对复合微球形貌的影响,确定了最佳包覆工艺。模板用量为0.2 g,六水合硝酸钆用量为0.7 mmol时,可得最佳包覆效果的核壳结构MF/Gd(OH)CO_3复合微球。以0.2 g粒径3μm的MF微球做模板,改变六水合硝酸钆用量为0.7 mmol、1.0 mmol,得到粒径为2.4μm,壳层厚度分别为100nm、200 nm的Gd_2O_3空心球。分别以粒径为2μm、3μm、4μm的MF微球做模板,固定六水合硝酸钆用量为1.0 mmol,模板用量0.2 g,制备出粒径为2.4μm、3.6μm、4.8μm的MF/Gd(OH)CO_3复合微球,随模板粒径的增大,复合微球的形貌变差。4.以粒径1.7μm的MF微球为模板,尿素为沉淀剂,五水硝酸镱为原料,利用均相沉淀法制备出核壳结构、粒径为1.9μm的MF/Yb(OH)CO_3复合微球。煅烧除去模板,得到粒径为1.5μm、球形度良好的Yb_2O_3空心球。XRD结果表明制备出的Yb_2O_3空心球为立方相,SEM、TEM结果表明空心球球形形貌良好。研究了五水合硝酸镱用量对复合微球形貌的影响,确定了最佳包覆工艺。MF模板用量为0.2 g,当模板粒径分别为1μm、1.3μm、1.7μm、2μm,五水合硝酸镱用量分别为0.4 mmol、0.5 mmol、0.7 mmol、0.75 mmol时,可得最佳包覆效果的核壳结构MF/Yb(OH)CO_3复合微球。经煅烧后,分别得到粒径为1μm、1.1μm、1.5μm、1.8μm的Yb_2O_3空心球。研究了模板粒径对复合微球形貌的影响。五水合硝酸镱的用量为0.8 mmol,模板用量0.1 g,分别以粒径为1μm、1.3μm、1.7μm、2μm的MF微球做模板,制备出不同形貌的MF/Yb(OH)CO_3复合微球。结果表明:模板粒径小于1.5μm时,包覆效果很差,模板粒径大于1.5μm时,包覆效果优良。
[Abstract]:In recent years, hollow shell materials with unique hollow structure have attracted wide attention. Because of their low relative density, high specific surface area, excellent packaging ability and good permeability, hollow spheres have been widely used in drug carriers, biocatalysis, disease diagnosis, optoelectronic devices and other fields. In this paper, melamine-formaldehyde (MF) microspheres with smooth surface, uniform particle size distribution and good monodispersity were prepared by the reaction of melamine with formaldehyde in aqueous solution catalyzed by formic acid. Yttrium oxide (Y_2O_3), gadolinium oxide (Gd_2O_3) and ytterbium oxide (Yb_2O_3) hollow spheres with different particle sizes were prepared by homogeneous precipitation method. The effects of template size and the amount of rare earth nitrate on the morphology of MF/RE (OH) CO_3 (RE=Y, Gd, Yb) composite microspheres were studied. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), X-ray diffraction (XRD). The main research contents and results are as follows: 1. The effects of formic acid dosage on the morphology and particle size distribution of MF microspheres were studied. The particle size of MF microspheres varied with the dosage of formic acid in the range of 0.01-0.3 mL. The MF microspheres prepared with 0.4 mL formic acid had a non-uniform particle size. When 0.5 mL formic acid was used, no MF microspheres were obtained. When 0.03 mL formic acid was used, the diameter of MF microspheres was 2 micron and the polydispersity coefficient was the smallest. In the range of 0.01-0.06 mL, with the increase of the amount of formic acid, the reaction time of the system was shortened rapidly and the reaction rate was accelerated. 2. Using MF microspheres with particle size of 2 micron as template, urea as precipitator and yttrium nitrate hexahydrate as raw material, the composite microspheres with particle size of 2.2 micron and core-shell structure of MF/Y(OH)CO_3 were prepared. The Y_2O_3 hollow spheres with particle size of 1.6 micron and good sphericity were obtained by calcining and removing the template. The optimum coating process was determined when the amount of yttrium nitrate was 0.2 g and yttrium nitrate hexahydrate was 0.8 mmol. The core-shell structure MF/Y(OH)CO_3 composite microspheres with the best coating effect were prepared by changing the amount of yttrium nitrate hexahydrate to 0.6 mmol, 0.8 mmol and 1.0 mmol. Y_2O_3 hollow spheres with diameter of 1.6 micron, shell thickness of 100 nm, 150 nm and 200 nm were obtained by calcining the template. 3. Using MF microspheres with diameter of 3 micron as template, urea as precipitator and gadolinium nitrate hexahydrate as raw material, the composite microspheres with diameter of 3.4 micron and core-shell structure of MF/Gd(OH)CO_3 were prepared by homogeneous precipitation method. The results of XRD show that the prepared Gd_2O_3 hollow spheres are cubic phase. The effect of the amount of gadolinium nitrate hexahydrate on the morphology of the composite microspheres was studied, and the optimum coating process was determined. MF/Gd(OH)CO_3 composite microspheres were constructed.The hollow Gd_2O_3 spheres with a diameter of 2.4 micron, a shell thickness of 100 nm and a thickness of 200 nm were obtained by changing the dosage of gadolinium nitrate hexahydrate to 0.7 mmol and 1.0 mmol with a diameter of 0.2 g and a diameter of 3 micron and a diameter of 3 micron as templates. MF/Gd(OH)CO_3 composite microspheres with particle size of 2.4 micron, 3.6 micron and 4.8 micron were prepared by 0.2 g. The morphology of the composite microspheres became worse with the increase of template size. 4. The core-shell structure of MF/Yb(OH)CO_3 composite microspheres with particle size of 1.7 micron was prepared by homogeneous precipitation method using urea as precipitator and ytterbium nitrate pentahydrate as raw material. Yb_2O_3 hollow spheres with a diameter of 1.5 micron and good sphericity were obtained by calcination. XRD results showed that the prepared Yb_2O_3 hollow spheres were cubic phase, SEM and TEM results showed that the spherical morphology of the hollow spheres was good. Yb_2O_3 hollow spheres with core-shell structure MF/Yb(OH)CO_3 were prepared by calcining the core-shell structure MF/Yb(OH)CO_3 composite microspheres with particle sizes of 1,1.1,1.5,1.8,0.4 mmol,0.5 mmol,0.7 mmol and 0.75 mmol, respectively. MF/Yb(OH)CO_3 composite microspheres with different morphologies were prepared by using Ytterbium nitrate pentahydrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template, Ytterbium nitrate as template.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ133.3

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