PS/TiO2核壳型微球和空心TiO2微球有序排列的制备

利用纳米级二氧化钛（TiO₂）溶胶微粒与聚苯乙烯（PS）胶体颗粒的混合悬浮液,以垂直共沉积的方法制备了核壳型PS/TiO₂微球的有序排列。当利用煅烧的方法去除PS胶粒晶体模板后,可以形成空心TiO₂微球的三维有序排列。考察了混合悬浮液中两种胶体颗粒的体积比（PS∶TiO₂=R）对空心TiO₂微球有序排列形成的影响。实验结果表明,合适的R值（6∶1）对于空心微球有序排列的形成至关重要。与此同时,浸渍填充法对照实验的结果表明,煅烧过程中TiO₂纳米颗粒晶型转化引起的收缩是造成TiO₂空心球产生的主要原因。     

PS/TiO2核壳型微球和空心TiO2微球有序排列的制备

利用纳米级二氧化钛（TiO₂）溶胶微粒与聚苯乙烯（PS）胶体颗粒的混合悬浮液,以垂直共沉积的方法制备了核壳型PS/TiO₂微球的有序排列。当利用煅烧的方法去除PS胶粒晶体模板后,可以形成空心TiO₂微球的三维有序排列。考察了混合悬浮液中两种胶体颗粒的体积比（PS∶TiO₂=R）对空心TiO₂微球有序排列形成的影响。实验结果表明,合适的R值（6∶1）对于空心微球有序排列的形成至关重要。与此同时,浸渍填充法对照实验的结果表明,煅烧过程中TiO₂纳米颗粒晶型转化引起的收缩是造成TiO₂空心球产生的主要原因。     

弱酸性溶液中快速制备PS/SiO_2空心微球及其应用研究

以聚乙烯吡咯烷酮为稳定剂,通过乳液聚合法合成了单分散聚苯乙烯(PS)微球。以PS微球为种子,在弱酸性溶液及不同温度下水解正硅酸乙酯(TEOS),一步合成了具有PS和SiO_2复合壳层的空心微球。研究了溶液p H及反应温度对微球空心度的影响,结果表明,能否得到空心微球受制于不同pH及温度下TEOS水解、缩聚速率以及所生成的纳米Si O_2对PS微球的包覆程度,溶液p H为3.0左右时,室温下反应就可以得到空心微球; p H升高至4.0～5.0时,反应温度达到40℃以上才可以得到空心微球; pH达到6.0时即使升温至50℃以上也无法得到空心微球。通过实验证实了空心SiO_2微球镀层不仅对玻璃具有增透效果,还可以使玻璃表面呈现出超亲水性。     

有序大孔二氧化硅微球的制备研究

采用乳液聚合法合成了单分散改性聚苯乙烯（PS）乳胶粒,利用PS乳胶粒自组装制得胶体晶体（“蛋白石”）微球,通过溶胶-凝胶模板法制备了有序大孔SiO2（“反蛋白石”）微球,通过SEM对改性PS乳胶粒、胶体晶体微球和有序大孔SiO2微球表面形貌进行了表征。结果表明,改性PS乳胶粒呈单分散性,粒径为317 nm;胶体晶体微球表面PS乳胶粒排列有序;有序大孔SiO2微球表面呈有序多孔,其孔呈六边形,孔径分布均一,约为200 nm。     

SiO_2/TiO_2复合纳米粒子的可控制备及表征

以聚丙烯酸(PAA)为模板,采用正硅酸乙酯(TEOS)水解法制备了SiO_2微球,在体系中加入钛酸四丁酯(TBOT),水解后在SiO_2表面自组装一层TiO_2,煅烧产物获得SiO_2@TiO_2空心球;通过TEM、XRD、固体紫外分光光度计对SiO_2@TiO_2的粒子形貌尺寸、晶型、紫外吸收特性等进行表征。结果表明,900℃下煅烧的SiO_2@TiO_2紫外屏蔽效果最好。为抑制TiO_2的光催化活性,在SiO_2@TiO_2表面再包覆一层SiO_2,得到SiO_2@TiO_2@SiO_2微球,具有抗紫外线、防沉降、对皮肤友好等优点。包覆之后的SiO_2@TiO_2@SiO_2三层结构仍具有良好的紫外屏蔽效果。     

空心球型二氧化硅担载Li_3PO_4催化剂的制备及催化效果研究

笔者以正硅酸乙酯(TEOS)为硅源,氨水溶液为催化剂,聚乙烯吡咯烷酮(PVP)功能化的聚苯乙烯为模板,在乙醇介质中利用一步法制得纳米空心二氧化硅,并用TEM、XRD、BET、TG、FTIR等表征手段对SiO_2粉体进行分析。首先,以苯乙烯(St)为单体,过硫酸铵为引发剂,聚乙烯吡咯烷酮为分散剂,水为分散介质,单分散聚合法制备功能化的聚苯乙烯,可得到平均粒径为90 nm的聚苯乙烯微球。以这种微球为模板,在乙醇/氨水介质中,正硅酸乙酯发生水解和缩合,在聚苯乙烯微球包覆形成SiO_2,同时PS核被溶解,得到纳米空心二氧化硅微球。研究氨水用量、TEOS用量及反应时间等因素对二氧化硅微球形貌和产率的影响。以空心纳米二氧化硅为Li_3PO_4催化剂载体,催化环氧丙烷的异构化,与以硅胶作为载体的Li_3PO_4催化剂的催化效果进行比较。结果表明,使用空心球形二氧化硅代替硅胶作为催化剂载体可提高环氧丙烷转化率和烯丙醇的选择性,降低反应温度和副产物选择性。     

利用不同造孔剂制备Al2O3多孔陶瓷

以炭黑和自制的PS微球（聚苯乙烯微球）、PMMA微球（聚甲基丙稀酸甲酯微球）为造孔剂制备氧化铝多孔陶瓷,通过SEM和其他方法对其强度、密度、外观形貌进行比较。结果表明,用PS微球与PMMA微球为造孔剂的多孔陶瓷在强度、气孔率等这些方面对多孔陶瓷的影响相近,炭黑对多孔陶瓷的各方面影响最大,以炭黑为造孔剂的多孔陶瓷比以PS微球与PMMA微球为造孔剂的多孔陶瓷的强度大、但是气孔率的稳定性差且不易控制。     

采用模板法制备毫米级半透明Al2O3空心球EI北大核心CSCD

以自制毫米级聚苯乙烯(PS)球为模板,采用物理包覆和真空烧结方法制备Al2O3半透明空心球。用离心加压物理包覆法制备PS–Al2O3复合球壳,经3步煅烧法制备出毫米级半透明氧化铝空心球。制备过程为:第1步以1℃/min的升温速率在320℃保温2 h和900℃保温2 h,去除模板得到白色氧化铝空心球素坯;第2步在1 300℃保温2 h,去除残余模板和大部分气孔,对氧化铝空心球壳预烧结;第3步在1 800℃真空条件下烧结,得到半透明氧化铝空心球,其球壳厚度约为150μm,具有较高的致密度,可用作惯性约束核聚变靶丸材料。     

交联PS微球表面PEMA刷子的合成与表征

将含有双键的N，N-二甲氨基甲基丙烯酸乙酯化学锚接在交联聚苯乙烯（PS）微球表面,再用过氧化苯甲酰引发甲基丙烯酸乙酯（EMA）氮氧调控自由基原位接枝聚合反应．将聚甲基丙烯酸乙酯（PEMA）接枝在交联PS微球表面，制备了PEMA刷子层；研究了聚合反应机理．并对所合成交联PS接枝PEMA共聚物进行了表征。结果表明，在2，2，6．6-四甲基哌啶-1-氧自由基存在下，EMA的聚合反应为“活性”自由基聚合．所得到的PEMA摩尔质量分布在1．18—1．3范围，摩尔质量随聚合时间的延长而增大（9000～57000g／mol）；红外光谱显示PEMA被接枝到了交联PS微球表面，交联PS微球粒径在0．5—1．2μm之间。     

水热法合成SiO_2@Ag核壳纳米微球

通过控制单一变量(反应时间、水醇比例、还原剂种类、氨水用量、还原剂用量),利用高温水热法,直接在SiO_2微球表面沉积Ag纳米粒子,制备SiO_2@Ag纳米核壳微球。通过SEM、XRD和FT-IR对SiO_2@Ag核壳纳米微球的形貌与结构等进行表征,研究各反应条件对载银量的影响规律,以此来确定SiO_2@Ag的最佳实验条件。结果表明,在最佳反应条件下,用水热法可使Ag纳米粒子致密均匀地包覆在SiO_2微球表面,并且SiO_2微球表面包覆的是Ag纳米粒子,而不是Ag_2O。     

Photonic bandgap of inverse opals prepared from core-shell spheres

ABSTRACT: In this study we synthesized the monodispersed polystyrene (PS)-silica core-shell spheres with various shell thickness for the fabrication of photonic crystals. The shell thickness of spheres was controlled by the various additions of tetraethyl orthosilicate during the shell growth process. The shrinkage ratio of the inverse opal photonic crystals prepared from the core-shell spheres was significantly reduced from 14.7% to within 3%. We suspected that the improvement resulted from the confinement of silica to the contraction of PS space during calcination. Due to the shell effect, the inverse opals prepared from the core-shell spheres have the higher filling fraction and the larger wavelength of stop band maximum.     

Synthesis of porous hollow silica spheres using functionalized polystyrene latex spheres as templates

Uniform sized and integrated hollow silica spheres with porous shells were prepared by using sulfuric and carboxylic acid-functionalized polystyrene latex spheres as templates, sodium silicate as a precursor, and cetyltrimethylammonium bromide as a shell structure-directing agent. When polystyrene-methyl acrylic acid latex spheres were used as the templates, the pores in the shells of the resultant hollow silica spheres were composed of both micropores and mesopores. The pores in the shells of the hollow silica spheres were mainly composed of mesopores when sulfonated polystyrene-methyl acrylic acid latex spheres were used as the templates. The shell thickness and the specific surface area of the hollow silica spheres increased with the increase in the surface acidity of the latex spheres.     

Synthesis of modified silica spheres used for the preparation of dual ultraviolet‐ and thermo‐cured epoxyacrylate/silica composites

To investigate the interfacial effect on properties of epoxyacrylate–silica composites, submicron‐sized silica spheres were synthesized by sol–gel reaction under a basic environment and their surfaces were endowed with vinyl functional groups by further modification with 3‐methacryloxypropyl trimethoxy silane. The pure silica (PS) and the modified silica (MPS) spheres were characterized by Fourier transform infrared, ²⁹Si‐ and ¹³C‐nuclear magnetic resonance (NMR), scanning electron microscope (SEM), and particle size analyzer. The silica spheres were then added to the presynthesized difunctional epoxyacrylate resin with one vinyl group and one epoxide group at each end, in addition to the photo‐ and thermo‐curing agents. After cure, thermal and mechanical properties of the obtained epoxyacrylate–silica composites were measured and compared. Tensile mechanical properties including initial modulus, ultimate tensile strength, and elongation at break, as well as the fracture energy of the epoxyacrylate–silica composite were all increased by increasing the content of silica spheres. Moreover, the composites filled with MPS had stronger interfacial strength between silica sphere and matrix than those with PS and thus exhibited an additional increase of tensile mechanical properties and fracture toughness. The increase of fracture toughness was owing to the crack deflection and particle–matrix debonding as evidenced by SEM pictures on the fracture surface. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

核-壳型聚苯乙烯/二氧化硅复合微球的制备

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，并对复合微球的热分解过程进行了研究．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；比较PS，SiO2和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．在吸附相同层数的前提下，随着所选用的二氧化硅纳米粒子的粒径的增大(10-40nm)，复合微球的粒径增大，空腔球体的壁厚增加，中心粒子热分解的活化能增大．复合微球的热分解机理符合三维扩散机理．     

Synthesis of stable hollow silica nanospheres

Hollow silica nanospheres with their size distribution ranging from 350 nm to 450 nm are synthesized by using polystyrene (PS) templates in the present study. On the basis of PS templates, silica, the hydrolyzate of TEOS(tetraethyl orthosilicate) under moist alkaline condition at ambient temperatures and atmospheric pressures, it is set to be coated on the surface of the PS spheres. Since the size of PS sphere core can be easily controlled, it is expected to serve various needs of different sized hollow silica nanospheres in industrial applications. It is proposed that the PS cores be removed by either thermal pyrogenation or solvent dissolved. Morphology of the hollow silica nanospheres is characterized by scanning electron microscopy (SEM).     

油性介质中组装二氧化硅胶体晶体薄膜

报道厂一种由粒径大于700nm的SiO2微球组装胶体晶体薄膜的方法。以一种密度较大的疏水性有机物替代水或醇类为分散剂,通过对SiO2微球表面进行疏水性处理改善其在油性介质中的分散性,采用改进的垂直沉积法在油性分散剂中制备SiO2胶体晶体。用扫描电子显微镜、红外光谱仪和紫外－可见光谱仪对SiO2胶体晶体薄膜的形貌、结构和光学性能进行了观察测试。结果表明;较大密度的分散剂能有效降低SiO2微球的沉降速度,组装成直径在700～2000nm范围的SiO2微球的胶体晶体。获得的SiO2光子晶体具有长程有序结构,并在近红外区具有显著的光子频率带隙。     

Preparation of spherical macroporous silica in an aerosol phase

Macroporous silica (MS) and macro/mesoporous silica (MMS) were prepared by spray drying a polystyrene (PS) latex sol containing a silica source, followed by calcination. As a silica source, 3-aminopropyl triethoxysilane (APS) was used for MS while either silica sol (SS) or tetraethoxyothosilicate using P123 templating (P123-TEOS) was used for MMS. Spray drying and calcination could also take place in a once-through aerosol reactor. The transformation of the silicon alkoxides to silica and decomposition of PS occurred at similar temperatures. Therefore, for APS-originated MS, the metal additives such as silver and nickel were required to accelerate the former. In addition, the nickel was well dispersed in the silica matrix during calcination even at 800 °C, in turn to thermally stabilize the porous structures. The wall-preforming additives were unnecessary for PS/SS and PS/P123-TEOS, since the SS drying and P123 templating, respectively, took place at lower temperature than PS decomposition. The porosities of all the porous silica prepared ranged from 0.54 to 0.57, which were close to the volume fraction of PS in the PS-alkoxides mixture solidified right after spray drying.     

A comparative study on the preparation and physical properties of environmental friendly PMMA‐silica nano/sub‐micron‐scale hybrid latexes controlled by chelating agent

In this article, a comparative study of the preparation and physical properties of as‐prepared PMMA‐silica nano‐hybrid (PSN) and sub‐micro‐hybrid (PSM) latexes is successfully presented. Vinyl‐modified silica spheres were prepared using the Stöber process with/without a chelating agent to control particle size. The as‐prepared vinyl‐modified silica spheres with different particle sizes were subsequently characterized by SEM, ¹³C‐solid‐state NMR, and ²⁹Si‐solid‐state NMR spectroscopy. A certain feeding amount of silica spheres was reacted with MMA monomers by emulsion polymerization to yield a series of PSN and corresponding PSM. Both as‐prepared nano/sub‐micronscale hybrid materials were further characterized by FTIR, SEM‐EDX mapping, and TEM studies. The comparative study on the physical properties of both as‐prepared nano/sub‐micron‐scale hybrid materials was done systematically based on a series of instrumentation evaluations performed using a dynamic mechanical analyzer, electrochemical corrosion measurements, salt spray test, and gas permeability analysis. Results indicated that PSN has more effectively enhanced mechanical properties, corrosion protection properties, as well as gas barrier compared to PSM. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

二氧化硅球的制备及其功能化

以正硅酸四乙酯为硅源,分别在碱性和酸性条件下制备了二氧化硅(SiO2)球状粒子;在碱性条件下制备了具有荧光功能的SiO2-FITC复合纳米球;以Sn2+作为敏化剂,在SiO2球表面沉积Ag纳米颗粒,制备了SiO2/Ag核-壳结构纳米粒子。通过透射电子显微镜(TEM)、紫外-可见近红外(UV-vis-NIR)分光光度计,荧光分光光度计对SiO2球,SiO2-FITC荧光纳米球,SiO2/Ag核-壳结构纳米粒子的形貌和光学吸收、荧光发射特性进行了表征。结果表明,碱性环境下制备的SiO2球粒径大小为纳米级,酸性环境下制备的SiO2球粒径大小为微米级,酸性环境下制备的SiO2球比碱性环境下制备的硅球致密。掺入FITC的SiO2球具有荧光发射特性,且发光强度可以控制。Ag纳米颗粒修饰的SiO2/Ag核-壳结构纳米粒子具有等表面等离子体共振吸收特性。     

Preparation of monodispersed PNIPAm/silica composites and characterization of their thermal behaviors

Two types of thermosensitive poly(N-isopropylacrylamide) (PNIPAm)-silica organic/inorganic hybrid particles were successfully prepared in aqueous solution through a facile synthetic process. Silane coupler of vinyl organic groups connects the PNIPAm to silica. First, hybrid spheres were prepared by grafting PNIPAm polymers to VTMS (vinyl trimethoxysilane) silica spheres. The thickness of polymer shell on the silica surfaces could be easily controlled by varying the concentrations of NIPAm monomer. Second, another type of hybrid particle was fabricated by encapsulating PNIPAm polymer with silica materials. The PNIPAm polymers were completely encapsulated by silica shell. The morphologies and shell thickness were characterized through SEM and TEM. The variations of phase transition temperature of PNIPAm were measured using DSC.