四丁基氢氧化铵辅助的二氧化硅粒子尺寸与形貌调控

发布时间：2018-06-16 01:11

本文选题：St(?)ber法 + 四丁基氢氧化铵　；参考：《吉林大学》2017年硕士论文

【摘要】：二氧化硅(SiO_2)粒子具有优良的化学稳定性和生物相容性,近年来在工业催化、生物成像、临床检验等领域展现了广阔的应用前景,是目前研究者最关注的粒子体系之一。目前,二氧化硅粒子的制备多采用St(?)ber法,即在乙醇/水混合溶剂中,以氨水为催化剂,正硅酸四乙酯(TEOS)为硅源,通过一系列水解/缩合过程而获得SiO_2粒子。然而,目前对于St(?)ber法中水解/缩合平衡的变化规律与SiO_2生长机制及其微结构联系的研究仍处于初级阶段,在粒子尺寸及形貌调控,尤其是制备小尺寸(10 nm)以及非球形SiO_2粒子方面仍较为困难。因此,本论文主要研究了二氧化硅(SiO_2)粒子的可控合成。通过向经典的St(?)ber体系中引入有机强碱四丁基氢氧化铵(TBAOH)作为助催化剂,系统研究了TBAOH对体系中TEOS水解/缩合过程的影响,并以此为基础调控SiO_2粒子的尺寸与形貌,实现了小尺寸(10 nm)及非球形SiO_2粒子的可控制备。主要的工作内容包括:1.在St(?)ber法制备SiO_2粒子的研究基础上,加入TBAOH作为助催化剂,TBAOH是一种有机强碱,其电离的OH-和TBA+均会对SiO_2的成核生长过程产生一定的影响。OH-促进了TEOS的水解缩合速率,增加了成“核”量,从而抑制初级粒子的聚合生长,TBA+浓度的提高则增加了离子强度,从而促进粒子的聚集生长,本论文利用这一机理,通过调整助催化剂TABOH的浓度,制备了一种尺寸可调、稳定分散的小尺寸SiO_2粒子(6-35 nm),并通过电导率,红外光谱研究了不同浓度TBAOH对SiO_2成核生长过程的影响。固定NH3·H2O浓度为0.3 M,当助催化剂TBAOH的浓度分别为0,0.2,0.4,0.6,0.8,1.0,2.0 m M时,制备的SiO_2粒子尺寸分别为10,28,35,27,20,16,6 nm;实验结果表明,随着进一步增加TBAOH浓度,粒子的尺寸先增大而后减小,当TBAOH浓度为0.4 m M时,获得的SiO_2粒子尺寸最大(35 nm),当TBAOH浓度为2.0 m M时,获得的SiO_2粒子尺寸最小(6 nm)。透射电镜以及动态光散射结果表明,利用这种方法制备的SiO_2粒子具有良好的单分散性,可与传统的St(?)ber法相比拟。2.利用TBAOH先催化TEOS反应一段时间后(预水解过程),在体系中补加NH3·H2O继续反应,制备出非球形的SiO_2粒子。通过改变NH3·H2O浓度,调控SiO_2粒子的尺寸,粒子尺寸随NH3·H2O浓度升高而变大,随NH3·H2O浓度降低而变小。在NH3·H2O浓度一定的情况下,通过改变预水解时间,调控SiO_2粒子的形貌。实验结果表明:当预水解时间分别为0,20,40,60,90,120,150 min,获得的花生状SiO_2粒子,其长径比分别为1.00,1.06,1.58,1.84,3.06,5.17,6.82。随着延长预水解时间,粒子长径比逐渐增大。预水解时间越长,TEOS水解越完全,体系内成“核”数越多,越容易聚集,从而获得不同尺寸的非球形SiO_2粒子。
[Abstract]:Silicon dioxide (SiO_2) particles have excellent chemical stability and biocompatibility. In recent years, it has been widely used in the fields of industrial catalysis, bioimaging, clinical testing and other fields, and is one of the most concerned particle systems. At present, the preparation of silica particles is mostly used in the St (?) BER method, that is, in the ethanol / water mixed solvent. With ammonia as the catalyst and four ethyl orthosilicate (TEOS) as the silicon source, SiO_2 particles are obtained by a series of hydrolysis / condensation processes. However, the study on the change of the hydrolysis / condensation equilibrium in the St (?) ber method and the relationship between the SiO_2 growth mechanism and the microstructure of the SiO_2 is still in the primary stage, and the particle size and morphology control, especially the preparation, is made. Small size (10 nm) and non spherical SiO_2 particles are still relatively difficult. Therefore, this paper mainly studies the controllable synthesis of silica (SiO_2) particles. By introducing organic strong alkali and four Butyl Ammonium Hydroxide (TBAOH) into the classical St (?) ber system as a co catalyst, the effect of TBAOH on the hydrolysis / condensation of TEOS in the system is systematically studied. Ringing and controlling the size and morphology of SiO_2 particles on this basis, the controllable preparation of small size (10 nm) and non spherical SiO_2 particles is realized. The main work contents include: 1. on the basis of the study of SiO_2 particles in the St (?) ber method, TBAOH is added as a co catalyst, TBAOH is an organic strong base, and the ionized OH- and TBA+ will all be to SiO_2. The nucleation growth process has a certain effect on.OH-, which promotes the hydrolysis condensation rate of TEOS, increases the "nucleation" and inhibits the polymerization of primary particles. The increase of TBA+ concentration increases the ionic strength, thus promoting the aggregation and growth of the particles. This paper uses this mechanism to prepare the catalyst TABOH by adjusting the concentration of the catalyst. A small size SiO_2 particle (6-35 nm) with adjustable size and stable dispersion, and the influence of different concentrations of TBAOH on the nucleation process of SiO_2 by electrical conductivity and infrared spectroscopy. When the concentration of NH3. H2O is 0.3 M, and when the concentration of Co catalyst TBAOH is 0,0.2,0.4,0.6,0.8,1.0,2.0 m M, the size of the prepared SiO_2 particle is respectively 5,27,20,16,6 nm; the experimental results show that the size of the particle first increases and then decreases with the increase of TBAOH concentration. When the concentration of TBAOH is 0.4 m M, the size of the SiO_2 particle is the largest (35 nm). When the concentration of TBAOH is 2 m M, the size of the SiO_2 particle is the least (6). Transmission electron microscopy and dynamic light scattering results show that the use of this method is the use of this method. The prepared SiO_2 particles have good monodispersity, which can be compared with the traditional St (?) ber method..2. uses TBAOH to catalyze TEOS reaction for a period of time (pre hydrolysis process). The non spherical SiO_2 particles are prepared by adding NH3 H2O in the system. The size of the SiO_2 particles is regulated by changing the NH3 H2O concentration, and the particle size depends on the size of the particle size. The concentration of H2O increases and decreases with the decrease of NH3 H2O concentration. Under a certain concentration of NH3. H2O, the morphology of SiO_2 particles is regulated by changing the prehydrolysis time. The experimental results show that when the pre hydrolysis time is 0,20,40,60,90120150 min, the peanut like SiO_2 particles are obtained, and the ratio of the length to diameter is 1.00,1.06,1.58,1.84,3.06, respectively. The length to diameter ratio of 5.17,6.82. increases with the prolongation of prehydrolysis time. The longer the pre hydrolysis time is, the more complete the hydrolysis of TEOS, the more the number of nucleation in the system, the more easy to gather, thus obtaining different sizes of non spherical SiO_2 particles.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.72

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