共查询到20条相似文献,搜索用时 187 毫秒
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以硅酸钠为硅源,硫酸为酸化剂,聚乙二醇为模板剂,利用均相反应器水热法制备了介孔二氧化硅微球.考察硅酸钠、硫酸、聚乙二醇的浓度及聚乙二醇聚合度对产物形貌和材料表面特性的影响,研究了介孔二氧化硅微球的形成机理.运用XRD,FT-IR,XRF,SEM,BET等手段对产品进行表征.从表征结果可以看出,所制备的介孔二氧化硅微球球形度良好,粒径分布比较均匀,纯度高,比表面在92~577 m2/g、孔体积在0.141~1.141 cm3/g范围内可调控.通过TEM对聚乙二醇胶束的研究得到介孔二氧化硅微球的形成机理. 相似文献
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SiO2单分散溶胶微球制备的工艺条件研究 总被引:1,自引:0,他引:1
在乙醇介质中,以氨作为催化剂,正硅酸乙酯作为硅源,制备了单分散的二氧化硅溶胶微球。通过激光粒度分析仪及透射电镜测定溶胶粒子的大小。研究了不同工艺参数如催化剂和水的量、硅源的量以及溶剂的类型对二氧化硅粒子大小及形貌的影响,并考察了粒子的形成机理。结果显示:随着氨浓度的升高,溶液初始解离的[OH-]增大,二氧化硅粒子的粒径增大;随着硅源浓度的增加,溶液中水解的中间产物增加,二氧化硅微球的粒径显著增加;在r(水/正硅酸乙酯)值远大于4的情况下,随着初始加入水量的增加,二氧化硅微球的粒径有所增加,但当水量太多时,粒径反而下降;使用不同溶剂作为制备二氧化硅的介质,在丙醇和丁醇中二氧化硅严重团聚,没有得到单分散微球。 相似文献
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单分散二氧化硅微球的制备与表征 总被引:1,自引:0,他引:1
通过Stober法合成了单分散的二氧化硅微球,系统地研究了反应条件对成球粒径及单分散性的影响,通过透射电子显微镜对其进行了表征。随着氨水和正硅酸乙酯浓度的提高,生成的二氧化硅微球的粒径逐渐减小。而温度升高的条件下则会形成粒径较小的微球,溶剂粘度的升高也会增大形成的微球的粒径。另一方面,向反应体系中加入电解质可以有效地增大球的粒径,从而为制备微米级的二氧化硅微球提供了一种简单有效的方法。研究了相关的反应机理,根据这些反应条件的变化可以确定制备不同粒径单分散二氧化硅微球的条件。 相似文献
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两相溶胶-凝胶法制备微米二氧化硅 总被引:2,自引:1,他引:1
采用两相溶胶-凝胶法,以正硅酸乙酯、氨水、乙醇、水、微量电解质为原料,制备出微米级单分散性二氧化硅微球,着重研究了微量电解质加入量、加料时间、加料方式、不同溶剂配比对二氧化硅微球粒径的影响.结果表明,二氧化硅微球粒径随着电解质浓度的增大先减小后增大;随着加料时间的延长,二氧化硅微球粒径逐渐增大;连续加料比间歇加料制得的二氧化硅微球单分散性好;溶剂类型对二氧化硅微球粒径有很大影响,通过不同溶剂配比调控二氧化硅微球粒径,最终制备出单分散性好的微米二氧化硅微球. 相似文献
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以硅溶胶为硅源,采用聚丙烯酰胺作为结构导向试剂,反相悬浮聚合法制备了介孔二氧化硅微球。控制引发剂过硫酸钾、交联剂N,N-亚甲基双丙烯酰与单体丙烯酰胺的加入量,获得球形度以及分散性较佳的聚丙烯酰胺复合二氧化硅微球。焙烧去除聚丙烯酰胺模板后得到的二氧化硅微球通过光学显微镜、红外光谱FT-IR、X-射线衍射以及氮气吸附脱附等手段进行了表征,证明聚丙烯酰胺在制备中起到了良好的结构导向作用,获得的二氧化硅微球的比表面积为240m2/g,孔径均匀分布于9nm左右,孔容度为0.3cm3/g。该方法可以通过改变转速的方法控制硅球的粒径。 相似文献
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以水玻璃(硅酸钠溶液)作为起始硅源,通过阳离子交换树脂得到硅酸溶液,进而采用反相悬浮聚合法制备了多孔结构的二氧化硅微球,并考察了乳液放置时间以及碱热处理条件对于微球的形貌、比表面积、平均孔径及孔容的影响.实验发现,此方法可制备10 ~ 100 μm球形圆整的二氧化硅微球,比表面积SBET可控变化区间为124.3~597.3 m2/g,平均孔径2.487~13.97 nm,孔容0.3354 ~0.8314 cm3/g.同时,利用基本粒子生长和堆砌的机理解释了不同孔结构形成的原因.为制备粒径和孔径可控的微米级二氧化硅球提供了一种成本低且简单有效的方法. 相似文献
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以Na2SiO3为前驱物,研究了碳化合成纳米SiO2颗粒比表面积的控制机理. 正交实验结果表明,影响其比表面积的次序为Na2SiO3浓度>PEG6000添加量>反应温度>CO2/N2混合气流量. 当反应温度80℃、Na2SiO3浓度40 g/L、PEG6000 4 g/L、CO2/N2混合气流量1.2 L/min时,所制SiO2颗粒的比表面积为318.9 m2/g. 随Na2SiO3 浓度增大,SiO2胶粒在pH>7的碳化液中Ostwald凝聚生长过程相对延长,颗粒的一次粒径增大,比表面积却随之减小. 由于温度对SiO2溶解度和胶粒Brownian运动的影响,降低反应温度可促进SiO2成核、减少Si(OH)4和≡SiOSi(OH)3的聚合,SiO2颗粒的比表积增大. 添加剂PEG6000的空间架构效应抑制纳米SiO2颗粒团聚,从而促进SiO2颗粒比表面积增大;但当其浓度大于7 g/L时,Na2SiO3分子进入缠绕着的PEG长链架构内部,所得SiO2颗粒比表面积有所降低. 相似文献
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Selvaraj Ranjith Priyan Govindan Suresh Kumar Srinivasan Surendhiran Mohd. Shkir 《International Journal of Applied Ceramic Technology》2023,20(5):2807-2816
Mesoporous silica nanoparticles with distinct characteristics like particle size, tunable pores, and high surface area have received much interest for environmental remediation, energy conversion, and biological applications. In this work, we synthesized spherical silica nanoparticles with tunable particle size and mesoporous properties using a low-cost silica source (rice husk) and polyethylene glycol (PEG) via microwave-assisted sol–gel synthesis. The formation of an amorphous silica structure was found using XRD and FTIR analysis. FESEM analysis showed that altering the PEG concentration from .01 to .005 M produced spherical silica nanoparticles with 100–500 nm in size. Nitrogen adsorption–desorption demonstrated that silica nanoparticles obtained with .005, .007, and .01 M of PEG had unique pore sizes and distributions, with specific surface areas of 51.475, 62.367, and 84.251 m2/g, respectively. These results might be due to PEG molecules’ capping effect, which acts as a soft template to regulate particle size, pore size, and dispersion by interacting with sodium silicate precursor. Hence, this approach can be a facile and cost-effective method to prepare mesoporous silica nanoparticles with controllable nanoscale characteristics for suitable applications. 相似文献
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So Yeun Kim 《Polymer》2005,46(19):7974-7981
Bifunctional polyurethane-based macromonomers (BPUM) were synthesized from various molecular weights of polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI) with different end group functionalities. The synthesized BPUMs were applied to the dispersion polymerization of styrene in ethanol. Structures of various macromonomers and PS particles were investigated using 1H NMR. Molecular weights of PEG 1000, 2000, 4000, and 8000 were able to provide stable particles of polystyrene (PS), whereas PEG 400 was not big enough to form stable particles. Although the final conversion was almost constant, average size of the PS microspheres increased with PEG molecular weights. The inverse relationship between the size of particles and molecular weight of PS was observed. In particular, the particle size based on the monomers derived with acrylamide was larger than acrylate derivative monomers. As the molecular weight of PEG increased, the thermal stability was enhanced and leveled off. The grafting ratio of the PS calculated from 1H NMR spectra exponentially decreased from 1.05 to 0.18 mol% with the increased molecular weight of PEG. Thus, present study suggests that the bifunctional macromonomers act not only as reactive stabilizers, but also as grafting agents in dispersion polymerization. 相似文献
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Polymer microspheres as fluid diverting agents have been applied for profile control in deep reservoirs. However, its reservoir adaptability strictly requires the matching between the particle size and the pore radius, which are hard to realize due to uncertainty of pore radius caused by long-term water flooding. That behavior has severely reduced their plugging performance to the large channel. The objective of this study was to prepare a kind of intelligent sustained-release microgel to solve the problem, which could slowly release of sodium silicate during migration, form the larger aggregates and plug high permeability reaching deep reservoir. We developed a novel blocking agent, which is an amphoteric microgel (OICMS) synthesized by light-initiated polymerization followed by the adsorption of a sodium silicate solution. The microgel properties, including the adsorption and release properties of a sodium silicate solution, and its influencing factors were investigated. The results showed that the OICMS had larger adsorption and release ratio of sodium silicate than conventional polymer microspheres, influenced by the ionic degree, molecular weight, amount of pore-forming agent, and cross-linking density. 相似文献
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The trimethylsilylation of sodium silicate in solution was carried out using magnetic and ultrasonic mixing. The maximum yield of trimethylsilylated product was obtained by magnetic stirring. The product having the higher molecular weight was formed using ultrasonic as well as magnetic mixing. The product was a white amorphous solid, soluble in most organic solvents. 相似文献
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采用共沉淀法制备纳米Fe3O4磁粒子,经离心分离后利用超声分散将纳米磁粒子弥散于壳聚糖溶液中形成了具有高度生物兼容性的壳聚糖包裹磁流体。利用XRD、TEM、红外光谱和磁天平对产物进行物性表征。探讨了壳聚糖质量、反应温度、超声分散时间和pH值对产物磁性的影响,结果表明:在反应温度为45℃,超声时间为55 min,pH值大于9,壳聚糖质量为0.15 g的条件下,制备的磁粒子约为15 nm左右,磁化饱和强度38.4 mT,抗氧化性高的壳聚糖包裹磁流体。该磁流体可作为X射线造影剂、靶向药物载体。 相似文献