介孔中空二氧化硅及硅基微球制备研究进展

介孔中空材料有特定孔道结构,具有中空、密度小、比表面积大的特点,因而具有较好的渗透性、吸附性、筛分分子能力和光学性能,成为具有广泛应用前景的热点研究材料。详细地介绍了国内外新型功能材料介孔中空二氧化硅及硅基微球主要制备方法,包括表面沉积法、层层组装法、原子转移自由基聚合法、喷雾法、微乳液法。同时介绍了合成的介孔、中空二氧化硅和硅基微球的形貌特点及应用。指出不同方法、不同制备条件对材料的形貌、孔径大小、孔形状及材料晶形有很大影响,条件温和、步骤简单、环境友好的制备方法是发展趋势。     

合成条件对径向有序介孔二氧化硅中空亚微米球的形貌和结构的影响

本文以硬模板与软模板结合的双模板方法(十六烷基三甲基溴化铵(CTAB)为介孔模板,聚苯乙烯(PS)球为中空模板),通过自组装制备出有良好分离性和单分散性且具有径向介孔的二氧化硅中空亚微米球.研究表明CTAB、TEOS的用量,催化剂的种类对二氧化硅中空亚微米球的形貌、壁厚、产品纯度等都有很大的影响.在保持其它实验条件不变的情况下,通过分别单独调节CTAB和TEOS的用量或同时调节CTAB和TEOS的用量,得出最佳原料配比是:TEOS/CTAB/NH3/乙醇/水的摩尔比是1∶0.27∶9.8∶304∶2955,TEOS/聚苯乙烯球的质量比是4/1.催化剂的种类对中空亚微米球的形貌也有较大影响,当NaOH(浓度为1 mol/L)的用量为0.05—0.10 mL时,生成由小粒子聚集而成的亚微米球;随着NaOH用量增大到0.10—0.20 mL,小粒子逐渐粘合在一起,亚微米球表面逐渐变光滑;进一步增大NaOH用量为0.20—0.30 mL则导致杂质小粒子的出现.在实验结果和文献报道的基础上,讨论并提出了径向有序介孔二氧化硅中空亚微米球的形成机理.     

介孔中空二氧化硅微球制备及吸附缓释性能研究

以用分散聚合法制得的不同粒径单分散阳离子型聚苯乙烯球为模板、十二胺为表面活性剂,通过溶胶-凝胶方法,在模板上包裹二氧化硅壳,并通过浸渍和焙烧制备了具有介孔结构的中空二氧化硅微球.TEM,SEM显示微球具有很好的单分散性和中空结构.小角XRD表明球壳上具有六方介孔结构.实验表明控制模板粒子大小可改变介孔中空二氧化硅微球粒径,改变正硅酸乙酯浓度可以调整二氧化硅球壳厚度.通过对丁基罗丹明B染料的吸附装载与释放实验证实了其有很好的渗透性和缓释性能.     

PICA法合成介孔二氧化硅研究

以硅酸钠为硅源,在酸性条件下,通过尿素和甲醛的缩聚反应,用诱导聚合胶体团聚法(PICA)制备出单分散脲醛/SiO2复合微球,并经高温煅烧制得介孔二氯化硅。通过X射线衍射(XRD)、氮气脱吸附、透射电镜(TEM)和高分辨透射电镜(HRTEM)等手段对介孔二氧化硅进行了表征。结果表明,通过PICA法制得的介孔二氧化硅有序性好,孔径较大、孔壁较厚、孔径分布均匀。     

单分散介孔二氧化硅微球的制备

在Stober方法基础上制备了单分散二氧化硅微球,系统研究了反应条件对成球粒径以及单分散性的影响。通过多种测试手段,发现随着正硅酸乙酯和氨水浓度的提高,成球的粒径逐渐增大;而温度的提高会促使氨水挥发而使得成球的粒径降低;反应时间在反应初期对成球粒径的影响很大,然后逐渐趋于平缓。经对煅烧前后产物的小角X射线衍射对比分析,发现煅烧后产物的峰强度增加,并且重叠峰向右漂移,指示表面活性剂分子从孔中移除并发生了孔径收缩现象,同时发现不同反应条件对产物的织构性质有一定的影响。研究了相关的反应机理,认为在碱性条件下二氧化硅微球由正硅酸乙酯的水解和缩聚两步过程完成的,该方法为制备单分散介孔二氧化硅微球提供了一种简单有效的并且可重复的路径,从而可能用于大批量生产。     

乙烷桥联型介孔二氧化硅纳米球的制备与表征

本文采用表面活性剂导向溶胶-凝胶法,在碱性条件下,通过两种硅源成功制备了乙烷桥联型介孔纳米粒子(MSN)。在合成MSN的基础上,以γ-(甲基丙烯酰氧基)丙基三甲氧基硅烷(MPS)为改性剂对MSN表面进行了修饰。结果表明:合成的MSN呈规整的纳米级球体,界面高度交联,具有直径分布均匀(260nm)的无机-有机杂化骨架,其比表面积、介孔尺寸和孔容分别为540m~2/g、3.7nm和0.52cm~3/g。     

硬模板法合成介孔中空纳米硅球及单分散研究

采用硬模板法制备出纳米级尺寸、分散性好、生物相容性高的介孔中空二氧化硅纳米微球(MHSiO_2),样品通过X-射线粉末衍射(XRD)、粒径分布动态光散射(DLS)进行测试。结果表明,MHSiO_2分散性较好,粒径约为130 nm,拥有100 nm的空腔结构,有望应用在药物的装载与运输方面。     

硬模板法合成介孔中空纳米硅球及单分散研究

采用硬模板法制备出纳米级尺寸、分散性好、生物相容性高的介孔中空二氧化硅纳米微球(MHSiO_2),样品通过X-射线粉末衍射(XRD)、粒径分布动态光散射(DLS)进行测试。结果表明,MHSiO_2分散性较好,粒径约为130 nm,拥有100 nm的空腔结构,有望应用在药物的装载与运输方面。     

介孔二氧化硅-阿维菌素缓释体系的制备与性能研究

以正硅酸乙酯(TEOS)为硅源,氨水为碱性催化剂,采用无模板法制备介孔二氧化硅和中空介孔二氧化硅,选用持效期较短的阿维菌素作为模型药物构成缓释体系,通过扫描电镜(SEM)、透射电镜(TEM)、比表面仪(BET)、傅里叶红外光谱仪(FTIR)和紫外分光光度计(UV)对二氧化硅材料的形貌、粒径、载药量进行表征和测定,同时测试其缓释性能。探讨了溶剂蒸发法和超声浸渍法两种不同载药方法对缓释性能的影响。结果表明,两种农药缓释载体均呈球形,平均粒径500 nm,其中中空介孔二氧化硅载体具有独特的中空介孔复合结构,超声浸渍法载药效果较好,两种载体的载药量分别为48. 89%和52. 58%,中空介孔二氧化硅-阿维菌素缓释体系的缓释区间较大,缓释效果较好,31 h才基本达到平衡。     

响应面法优化甘露醇产丁醇的发酵条件

以褐藻的主要成分甘露醇为底物,利用丙酮丁醇梭菌ATCC824发酵生产丁醇。采用Plackett-Burman（P-B）和Box-Behnken优化发酵条件。在Plackett-Burman实验设计时,考察牛肉膏、酵母浸粉、胰蛋白胨、乙酸铵、 KH2PO4、MgSO4?7H2O、FeSO4?7H2O、接种量、发酵温度、初始pH值这10个因素对丁醇产量影响,筛选出影响丁醇发酵的重要参数是发酵温度、初始pH值、乙酸铵浓度,利用Box-Behnken设计确定最优发酵条件为发酵温度37.3 ℃、初始pH值6.38、乙酸铵浓度2.82 g/L。数学模型分析预测最大丁醇产量为8.47 g/L。经实验验证表明,在优化条件下的丁醇产量平均值达到8.52±0.55 g/L。这说明利用统计学方法优化甘露醇的丁醇发酵条件是有效的。     

Improvement of hollow mesoporous silica nanoparticles synthesis by hard-templating method via CTAB surfactant

In this study, hollow mesoporous silicate nanoparticles using TEOS precursors in the presence of polystyrene template were synthesized. The process was performed in an alcohol-based chemical system and the addition of CTAB surfactant. The polystyrene template was used under controlled conditions having a spherical morphology with a uniform distribution and an average size of 50 nm. The results of the FTIR analysis showed that TEOS pre-cursor particles formed surface boundaries during the synthesis with CTAB surfactants, and also the presence of SiOSi bonds (in the 600 to 1320 cm⁻¹ range) indicates the formation of silicate chains on Polystyrene templates. Thermal analysis studies showed that by using appropriate thermal treatment and precise control, organic compounds can be removed from the system and synthesize hollow mesoporous silicate particles with minimum structural defects at 280 °C. The BET analysis showed that the specific surface area of these particles is 1180 m² g⁻¹. X-ray diffraction results demonstrated that the resulting product was amorphous silica and unwanted phases were not formed in this system. The dynamic light scattering analysis illustrated that the synthesized particles had dimensions ranging from 1 to 10 nm, and the particle size distribution occurred within a narrow range. Scanning electron microscopy images confirm the nodularity of nanoparticles with a mean size of 25–30 nm. Finally, the transmitted electron microscope images showed that the synthesized silicate particles were hollow, so that the diameter of the hollow chamber and its total diameter were about 30 and 80 nm, respectively.     

响应面法优化Fenton氧化处理高浓度废乳化液

采用Fenton氧化法对高浓度废乳化液处理进行了研究,基于Box-Behnken响应面法,考察了初始pH、FeSO_4·7H_2O加入量、H_2O_2加入量的单独作用和交叉作用,并建立了COD去除率数学模型,结果表明:影响因子显著性FeSO_4·7H_2O加入量初始pHH_2O_2加入量,初始pH与H_2O_2加入量的交叉作用显著;数学模型回归性较好,预测最佳COD去除率为89.46%。确定了Fenton氧化最佳条件为:初始pH为4.1,FeSO_4·7H_2O加入量为22 mmol/L,H_2O_2加入量为636 mmol/L,验证试验结果为89.11%,与拟合的二次回归模型预测值基本相符。     

Optimization of mesoporous alumina sol-gel synthesis by Taguchi and response surface methodology

Taguchi method (TM) and response surface methodology (RSM) have been employed to optimize three parameters, including the amounts of P123, the amounts of nitric acid and calcination temperature, in order to define an optimal setting for sol-gel synthesis of high surface area mesoporous alumina powder (MA). Herein, the comparison of the both statistical approaches has been examined and discussed considering the nitrogen adsorption as the response variable because this important character for mesoporous materials is exceedingly sensitive to the synthesis parameters. The BET surface area (S_BET) and pore volume of MA under Taguchi optimal condition were 323.5 m² g⁻¹ and 0.551 cm³ g⁻¹, respectively, by conducting confirmation test. Furthermore, the confirmation test showed high S_BET of MA (363.4 m² g⁻¹), which was in a good agreement with calculated S_BET result (431.25 m² g⁻¹) by a quadratic model under RSM optimal condition. Moreover, 3D response surface plots and 2D contour plots of desirability have been discussed to visualize the influence of input factors on response variable. It is also concluded that RSM shows more appropriate (12.33% higher S_BET than TM) and efficient optimal condition with determining a quadratic function as the relationship between S_BET and synthesis parameters.     

Silica foams with ultra-large specific surface area structured by hollow mesoporous silica spheres

Ceramic foams with multi-scale pores and large specific surface area have received extensive attention due to their unique structure and superior properties. Considering that there are still challenges to synthesize porous ceramics with large specific surface area, a novel ceramic foam material with ultra-large specific surface area has been prepared using hollow silica mesoporous spheres (HMSSs) as building block in this work. These building blocks were made weakly hydrophobic in order to produce HMSS particle stabilized foams. The foams exhibit a uniform primary macropore structure, which is composed of a three dimensional HMSS-assembled network, via HMSS-stabilized foams. The influence of sintering temperature on the microstructure and properties of HMSS foams is investigated. The HMSS foams exhibit highest specific surface area of 1733 m²/g, attributed to the radial mesopores in HMSS shell, when sintered at between 500°C and 800°C. This specific surface area is much higher than that of existing ceramic materials. The uniform pore structure and ultra-large specific surface area make it a promising lightweight material in potential application fields, including catalyst, adsorption, fire-resistant thermal insulation, and load and control release system.     

Facile synthesis of diamine-functionalized hollow mesoporous silica sphere with self-templating method

A new N-[3-(trimethoxysilyl)propyl]ethylenediamine-functionalized hollow mesoporous silica sphere (DA-HMSS) was synthesized by a two-step self-templating method, including hydrolysis and co-condensation of tetraethyl orthosilicate and N-[3-(trimethoxysilyl)propyl]ethylenediamine in the presence of ammonia solution and hexadecyltrimethylammonium bromide, following with hydrothermal incubation in pure water after the removal of hexadecyltrimethylammonium bromide. The successful formation of silica framework and incorporation of organic component in DA-HMSS were confirmed by Fourier transform infrared and solid-state ²⁹Si cross-polarization/magic-angle-spinning nuclear magnetic resonance spectroscopic measurements as well as CHN elemental analysis. The hollow morphology of DA-HMSS was revealed by transmission electron microscopy, whereas its porosity was disclosed by nitrogen adsorption–desorption isotherm measurement. Furthermore, its carbon dioxide adsorption capability was also investigated.     

Biodegradability of mesoporous silica nanoparticles

Biodegradability significantly impacts the bioapplication of mesoporous silica nanoparticles (MSN). In recent years, immense efforts have been made to understand and tailor the biodegradability of MSN. In this mini review, we overview the recent reports on the biodegradation of MSN, with a focus on the correlation between biodegradation and physicochemical properties including specific surface area, morphology, pore size, particle diameter and condensation degree of silicon-oxygen network. In addition, strategies for improving the biodegradability of MSN such as metal ions and organic species doping are also introduced.     

Dual responsive block copolymer coated hollow mesoporous silica nanoparticles for glucose-mediated transcutaneous drug delivery

A self-regulated anti-diabetic drug release device mimicking pancreatic cells is highly desirable for the therapy of diabetes. Herein, a glucose-mediated dual-responsive drug delivery system, which combines pH- and H₂O₂-responsive block copolymer grafted hollow mesoporous silica nanoparticles (HMSNs) with microneedle (MN) array patch, has been developed to achieve self-regulated administration. The poly[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl acrylate]-b-poly[2-(dimethylamino)ethyl methacrylate] (PPBEM-b-PDM) polymer serves as gate keeper to prevent drug release from the cavity of HMSNs at normoglycemic level. In contrast, the drug release rate is significantly enhanced upon H₂O₂ and pH stimuli due to the chemical change of H₂O₂ sensitive PPBEM block and acid responsive PDM block. Therefore, incorporation of anti-diabetic drug and glucose oxidase (GOx, which can oxidize glucose to gluconic acid and in-situ produce H₂O₂) into stimulus polymer coated HMSNs results in a glucose-mediated MN device after depositing the drug-loaded nanoparticles into MN array patch. Both in vitro and in vivo results show this MN device presents a glucose mediated self-regulated drug release characteristic, which possesses a rapid drug release at hyperglycemic level but retarded drug release at normoglycemic level. The result indicates that the fabricated smart drug delivery system is a good candidate for the therapy of diabetes.