纳米级TiO_2中空球的制备

以聚苯乙烯(PS)乳液为模板,首先合成了PS/TiO_2复合微球,采用回流溶解出PS模板的方法,制备出纳米级TiO_2中空球。探讨了不同单体浓度、引发剂用量、乳化剂用量以及反应温度对聚苯乙烯乳液的影响。利用XRD、TG、BET、IR和UV-Vis手段对合成的纳米颗粒进行了表征。研究发现80℃下,单体浓度占总质量的20%、引发剂和乳化剂分别为单体质量的0.3%和3%、回流时间为12h时,可以得到外径为180nm、比表面积为283.4m2/g的TiO_2中空球,且中空球的壳层由大量粒径为8~10nm的TiO_2颗粒紧密堆积而成。     

水热法制备二氧化铈纳米空心球及其吸附性能研究

用六水硝酸铈(Ce(NO_3)_3·6H_2O)作为铈源,以聚乙烯吡咯烷酮(PVP)为表面活性剂,在乙二醇的水溶液中通过水热法制备了单分散、粒径较均一的CeO_2纳米空心球。利用傅立叶转换红外分析(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、X射线能谱(XPS)、N_2等温吸附-解吸及紫外-可见光谱(UV-Vis)来表征CeO_2纳米空心球并研究其吸附性能。结果表明,水热法制备的CeO_2空心球是由立方萤石结构的纳米颗粒组装成的介孔中空材料,孔径分布窄,尺寸约为3~5 nm,空心球的直径约为400 nm,壁厚30 nm左右,空心球的BET比表面积为76.86 m2·g-1。讨论了CeO_2空心球的制备机理,所制备的CeO_2空心球对重铬酸钾溶液的吸附率可达到70%,约为CeO_2粉末的3倍。     

壳层厚度对核-壳结构PS-SiO_2杂化颗粒压缩弹性模量的影响

基于正负电荷间的静电作用制备了具有核-壳结构的聚苯乙烯-氧化硅(PS-SiO2)杂化颗粒,通过调节正硅酸乙酯的用量对样品的SiO2壳层厚度进行控制。利用原子力显微镜(AFM)在微观尺度上测定杂化颗粒的力-位移曲线,根据Hertz接触模型和Sneddon接触模型,考查了SiO2壳层厚度对样品压缩弹性模量的影响。扫描电子显微镜(SEM)和透射电镜(TEM)结果显示,杂化颗粒中PS内核尺寸为(197±9)nm,壳层由SiO2纳米颗粒组成,在本试验范围内杂化颗粒样品的壳厚为11~16nm。在Hertz接触模型条件下,PS微球的弹性模量为(2.2±0.5)GPa,其数值略低于PS块体材料。当SiO2壳厚由11nm增至16nm时,杂化颗粒的弹性模量从(4.4±0.6)GPa增至(10.2±1.1)GPa,其数值明显低于纯SiO2,且更接近于PS内核。     

氧化硅内核结构对核/壳包覆型SiO_2/CeO_2复合颗粒抛光性能的影响

设计合成了以具有放射状介孔孔道(孔径约2.6 nm)的介孔氧化硅(mSiO_2)微球(粒径约300 nm)为内核、以CeO_2纳米颗粒为包覆层(壳厚为15~20 nm)的m SiO_2/CeO_2复合颗粒(粒径在330~340 nm),使用场发射扫描电镜、透射电镜、X射线衍射、傅里叶转换红外光谱和氮气吸脱附等手段表征了样品的结构。结果表明,使用以实心氧化硅(sSiO_2)为内核的sSiO_2/CeO_2复合颗粒抛光的热氧化硅片其表面粗糙度均方根值(Root-mean-square roughness,RMS)为0.309 nm,材料的去除率(Material removal rate,MRR)为24 nm/min)。mSiO_2/CeO_2复合颗粒有利于得到更低的氧化硅片抛光表面粗糙度(RMS=0.267 nm)和更高的抛光速率(MRR=45 nm/min),且能避免出现划痕等机械损伤。SiO_2/CeO_2复合颗粒中的氧化硅内核结构,对其抛光特性有明显的影响。     

反蛋白石结构三维有序大孔CeO_2的制备和性能EI北大核心CSCD

以单分散聚苯乙烯(PS)微球为构筑单元,用双基片垂直沉积方法制备高度有序的PS胶体晶体模板,再用模板法合成了具有反蛋白石结构的三维有序大孔CeO_2(3DOM-CeO_2)。用X-射线衍射仪(XRD)、场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、原子力显微镜(AFM)和N_2吸脱附等手段对样品微观结构进行了表征,并借助H_2-TPR分析了样品的还原性能。结果表明:PS胶体晶体模板排列高度有序,呈多层面心立方结构紧密堆积;所制备的3DOM-CeO_2具有三维周期性排列的多孔结构,其孔间距在280-300 nm,壁厚约为40 nm;样品的大孔骨架由粒径为5-10 nm的CeO_2颗粒所组成;与纳米CeO_2标样相比,3DOM-CeO_2样品具有更好的低温还原性能。     

内核尺寸对核/壳结构PS/SiO_2复合磨料抛光特性的影响

核/壳结构有机/无机复合微球作为一种新型抛光介质,在实现高效无损伤抛光方面具有重要的应用价值。以无皂乳液聚合法制备的聚苯乙烯(PS)为内核,通过溶胶-凝胶法合成了一系列具有不同内核尺寸的PS/SiO2复合微球。利用FT-IR、FESEM和TEM等手段对样品进行表征,并借助AFM考察了复合磨料内核尺寸对SiO2介质层抛光质量的影响规律。结果表明,所制备单分散PS微球尺寸在200~600 nm,复合微球的壳层由SiO2纳米颗粒(5~10nm)所组成,壳厚在10~15 nm。材料去除率(MRR)随复合磨料内核尺寸的减小而降低,而抛光后晶片表面粗糙度(RMS)的变化则不明显。当复合磨料内核尺寸为210 nm时,抛光后RMS和MRR分别为0.217 nm和126.2 nm/min。提出将核壳结构有机/无机复合磨料理解成一种表面布满无机纳米颗粒的微型"抛光垫",尝试用有效磨料数量以及壳层中单个SiO2颗粒的压入深度对CMP实验结果进行解释,并进一步讨论了有机内核在抛光过程中的作用。     

核-壳式聚苯乙烯/二氧化硅复合微球及空腔硅球的制备

利用层层自组装的方法制备了粒径和组成可裁剪、具有核-壳式结构的单分散聚苯乙烯(PS)/二氧化硅(SiO₂)复合微球.对复合微球进行热处理除去有机物中心,制备出壁厚可剪裁的空腔硅球.透射电镜(TEM)照片显示二氧化硅纳米颗粒在中心外生成均匀壳层,而煅烧后则可得到轮廓分明的球形空腔;热重分析(TG)说明复合球体的硅含量随着所组装的纳米二氧化硅的粒径的增加而增加;比较PS、SiO₂、复合球体及热处理后的粉体的红外光谱,可分别验证二氧化硅的成功组装和热处理过程中作为中心的PS的完全去除.在吸附相同层的前提下,随着所选用的二氧化硅纳米粒子(10um,20um,40um)的粒径的增大,复合微球的粒径增大,空腔球体的壁厚增加.     

煅烧温度对TiO_2中空微球光催化性能的影响

以分散聚合法制得的单分散阳离子聚苯乙烯（PS）微球为模板,钛酸丁酯为前驱体,采用溶胶-凝胶法在模板表面包覆TiO2壳层,并在不同煅烧温度下制备了晶相结构不同的微米级中空TiO2微球。采用TEM、SEM、FT-IR、XRD、UV-Vis DRS对样品的微观结构、相态组成及光催化性能进行了表征。结果表明TiO2中空微球平均粒径达到1.23μm,壳层厚度约为30nm;随着煅烧温度增加,锐钛矿晶粒尺寸会增加,并在700℃时出现混晶结构;在500℃煅烧得到的TiO2中空微球对甲基橙（MO）降解表现出比P25更好的光催化性能及光催化稳定性。     

高分子中空微球的制备及其在聚硫密封剂中的应用

以甲基丙烯酸及甲基丙烯酸酯类单体为核、苯乙烯单体为壳层,通过种子乳液聚合法合成核壳结构的聚合物微球。采用碱酸分步处理的方法,将富含羧酸的微球内核充分离子化,通过溶胀离开微球,得到高分子中空微球。通过种子制备阶段乳化剂用量的控制可调控最终中空微球的粒径,并获得两种不同粒径的中空微球(分别为551nm和156nm)。将两种高分子中空微球分别与聚硫橡胶共混,制备出相应的聚硫密封剂。采用透射电子显微镜(TEM)、傅里叶红外光谱仪(FTIR)、电子拉力机对其结构、形貌、成分及其力学性能进行研究。结果显示:所制备的中空微球粒径分布均匀,中空度较高。添加高分子中空微球可以降低密封剂密度,同时提升其力学性能。相比较而言,粒径较大的高分子中空微球具有更好的应用效果。     

聚苯乙烯/银核壳结构纳米微球的制备与表征

采用两步法的简单路线制备出银纳米粒子包覆的聚苯乙烯(PS)微球,首先通过乳液聚合法合成出聚苯乙烯微球;然后对苯乙烯进行敏化和活化,搅拌下加入银的还原液,从而制备出Ag-PS核壳结构的纳米微球.同时借助于TEM、UV-vis、 FE-SEM进行表征,分析其微观结构.结果表明,所得的聚苯乙烯微球粒径约为40nm;聚苯乙烯/银核壳结构纳米微球粒径为45～350nm,银层厚度可随意调控.     

Simple fabrication of hollow poly-lactic acid microspheres using uniform microbubbles as templates

A simple method was developed that uses microbubbles as templates to fabricate hollow microspheres covered with a biodegradable polymer. By stably keeping microbubbles with the diameter of about 2 µm inside a solvent droplet dissolving a biodegradable polymer and then slowly drying the solvent, hollow microspheres that had an average inner diameter of about 2 µm and a shell thickness of about 500 nm were obtained. This simple method was successfully used to easily fabricate uniform hollow microspheres covered with poly-lactic acid (PLA) by using uniform 2-µm-diameter bubbles as templates.     

P(St-EA-MAA)模板法制备中空二氧化硅微球

以种子乳液聚合制得的P(St-EA-MAA)共聚物微球为模板,γ-氨丙基三甲氧基硅烷(APS)为助结构导向剂,正硅酸四乙酯(TEOS)为硅源,制备了P(St-EA-MAA)/SiO2复合微球,经高温煅烧除去聚合物模板,得到了中空二氧化硅微球。热重分析(TGA)表明模板剂的最佳脱除温度为600℃。高分辨透射电镜(HRTEM)观察显示所制得的二氧化硅微球具有典型的中空结构和良好的单分散性,其尺寸主要取决于共聚物微球的大小,通过调节微球模板的尺寸可以有效控制中空微球的大小。N2吸附-脱附曲线显示二氧化硅壁具有丰富的微孔,比表面积、平均孔径和孔容分别为117.87m2/g、1.98nm和0.21cm3/g。在制备复合微球的过程中加入一定量的CTAB可以调整中空微球的壁厚和壁的孔结构,使其比表面积、平均孔径和孔容增加到219.79m2/g、3.89nm和0.25cm3/g。     

聚苯乙烯/CeO2纳米复合微球的粒径及其影响因素

采用原位悬浮聚合法制备了聚苯乙烯/CeO2纳米复合微球。讨论了引发剂浓度、CeO2纳米粒子含量、分散剂聚乙烯醇浓度及复配分散剂等对纳米复合微球粒径及其分布的影响。结果表明,随着引发剂浓度和CeO2纳米粒子含量的增加,纳米复合微球粒径变小,粒径分布变窄;随着复配分散剂中聚甲基丙烯酸钠含量的增加,粒子粒径变小,粒径分别变窄。制得的聚苯乙烯/CeO2纳米复合微球粒径可控。     

Synthesis and characterization of ZrO2 hollow spheres

ZrO₂ hollow microspheres with the average diameter of about 500 nm and the shell thickness of about 50 nm were synthesized by a facile technique using carbon spheres as templates. The corresponding ZrO₂ hollow microspheres were obtained by calcining the precursors of C-Zr(OH)₄ core-shell heterostructures, which were synthesized with the precipitation of ZrCl₄ solution with aqueous ammonia on the surface of colloid carbons. SEM, XRD, TGA and BET were used to characterize the composition, morphology, size and crystal structure of synthesized products. The effects of ultrasonic dispersion and separation process on the hollow spheres were studied, and the surfactant PEG-1000 was added to tune the shell structure of synthesized ZrO₂ hollow spheres.     

Hollow MCM-41 microspheres derived from P(St-MMA)/MCM-41 core/shell composite particles

In soap-free latex media, poly(styrene-methyl methacrylate)/MCM-41 core/shell composite microspheres have been fabricated by adding silicate source in batches. In this process, silicate species and the surfactant micelles were self-assembled into 2-dimensional hexagonal arrangement on the surface of P(St-MMA) microspheres. Hollow MCM-41 microspheres were obtained via removing polymer core by solvent. XRD, TEM, IR and N₂ adsorption-desorption analysis were applied to characterize products. The results showed that average diameter and wall thickness of hollow MCM-41 microspheres is about 240 nm and 20 nm, respectively. Results of N₂ adsorption-desorption indicate that hollow MCM-41 microspheres possess a highly ordered mesoporous structure and a narrow pore distribution with a mean value of 2.34 nm.     

微纳分级结构碳酸钙中空微球的可控制备

以CaCl₂和Na₂CO₃为反应原料, 以聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDSN)为模板剂, 在50℃采用化学沉淀反应, 干燥、煅烧后成功制备了具有微纳分级结构的CaCO₃中空微球。采用扫描电子显微镜、透射电子显微镜和X射线衍射等检测手段对所制备的样品形貌、结构进行了表征, 结果显示：所制备的微纳分级结构CaCO₃中空微球直径为4~6 μm, 壳壁由直径约60 nm的CaCO₃颗粒组成, 壳层厚度约为200 nm, CaCO₃中空微球晶相组成为方解石和球霰石的共混体。同时, 在反应温度为50℃、PVP添加量为0.4 g, SDSN浓度为0.1 mol/L的条件下, 所制备的微纳分级结构CaCO₃中空微球分散性好, 且形貌比较完整。     

One-pot synthesis of porous hematite hollow microspheres and their application in water treatment

Alpha-Fe2O3 hollow micospheres have been successfully synthesized by solvothermal method at 200 degrees C. The synthesized products are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the nitrogen adsorption-desorption isotherm technique. The alpha-Fe2O3 hollow microspheres have an average diameter of 2-3 microm, the shell consists of numerous aligned nanorods with length of about 200-400 nm. The effects of solvent and reaction time have been studied. The Ostwald ripening mechanism is proposed to account for the formation of alpha-Fe2O3 hollow microspheres. Because of the porous hollow microstructure and large specific surface area, the microspheres were found to be effective sorbents for the removal of Cr(VI) ions from wastewater.     

Template-induced covalent assembly of hybrid particles for the facile fabrication of magnetic Fe3O4–polymer hybrid hollow microspheres

Magnetic Fe₃O₄–poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) hybrid hollow microspheres, in which Fe₃O₄ nanoparticles were firmly incorporated in the cross-linked PZS shell, have been fabricated through the formation of core/shell PS/Fe₃O₄–PZS composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property, and magnetic property of the magnetic hollow microspheres were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer respectively. Results indicated that the typical hollow microspheres had about 950 nm of inner diameter and about 210 nm of shell thickness, 440 °C of initial decomposition temperature under nitrogen atmosphere, and 13.3 emu g^?1 of magnetization saturation. Furthermore, the shell thickness of magnetic hollow microspheres could be easily controlled by tuning the mass ratio of PS to comonomers. As-fabricated hybrid hollow microspheres exhibit great potential as good catalyst supports.     

Gd_2O_3空心微球的制备及Gd_2O_3/丁基橡胶复合材料低频阻尼性能

以分散聚合法制备的聚苯乙烯(PS)微球作为模板,通过均相沉淀法制备前驱体PS-Gd(OH)CO_3复合微球,高温煅烧后得到Gd_2O_3空心微球,将其与丁基橡胶复合制备低频高阻尼Gd_2O_3/丁基橡胶复合材料。采用FTIR、SEM、TEM分析、TG分析仪、XRD分析和XPS对Gd_2O_3空心微球的形貌与结构组成进行表征。将Gd_2O_3空心微球与粉体分别作为填料加入丁基橡胶中制备Gd_2O_3/丁基橡胶复合材料。结果表明:Gd_2O_3空心微球由立方萤石结构的颗粒组成,外空心直径为0.9μm,壳层厚度约为100nm;添加空心微球的复合材料阻尼性能较好;与纯丁基橡胶相比,Gd_2O_3/丁基橡胶复合材料的低频阻尼性能明显提高。