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.     

Ni/PS核壳结构纳米复合微球的制备及磁性能

采用乳液聚合法制备了纳米级聚苯乙烯微球,利用化学沉积法在微球表面镀镍,制备出了具有磁性的金属/高分子(Ni/PS)纳米复合微球。利用透射电子显微镜(TEM)、X射线衍射仪(XRD)和能量色散谱仪(EDS)分别对镀镍前后纳米微球的形貌结构、相组成、化学成分进行表征分析,用振动样品磁强计(VSM)测试了不同制备工艺条件下复合微球的磁学性能。结果表明,活化工艺、还原剂浓度、镀液pH值和温度对镀后复合微球的磁性能有显著影响。根据磁性能结果,优化工艺参数,制备了具有规则球形、单分散性好、粒径约为100nm、镀层完整、均匀的磁性Ni/PS核壳结构纳米复合微球,并获得最大的饱和磁化强度Ms=8.8764emu/g。     

反相乳液法制备海藻酸钠/壳聚糖纳米微球

分别以吐温80和复合乳化剂司盘80/吐温80为乳化剂,采用反相乳液法,以大豆油为油相,氯化钙(CaCl2)为交联剂制得海藻酸钠(ALG)/壳聚糖(CS)纳米微球。采用SEM和激光粒度分析仪对纳米微球的形貌和粒径进行表征。结果表明,采用复合乳化剂司盘80/吐温80适合油包水体系,制得的ALG/CS纳米微球粒子为球形;采用复合乳化剂比采用单一乳化剂制备的纳米微球粒径分散指数小;随着司盘80∶吐温80的质量配合比不同,微球的粒径随复合乳化剂中吐温80量的增加而减少,粒径分散指数PDI值在0.1~0.2之间;当司盘80∶吐温80质量配合比为1∶1.4时,制得的纳米微球平均粒径最小为364.4nm;当司盘80∶吐温80质量配合比为1∶0.2时,制得的纳米微球平均粒径最大为1171nm。     

种子细乳液聚合法制备PVAc/PS复合微球形貌的研究

以乙酸乙烯酯(VAc)和苯乙烯(St)为单体,十六烷(HD)和聚苯乙烯(PS)为助稳定剂,十二烷基硫酸钠(SDS)为乳化剂,采用种子细乳液聚合法通过不同的加料顺序制备了不同形貌的聚苯乙烯(PS)/聚乙酸乙烯酯(PVAc)复合微球。考察了乳化剂和助稳定剂的用量对聚合稳定性的影响。采用红外光谱(FTIR)、透射电子显微镜(TEM)和热失重分析(TGA)等方法对复合微球进行了表征。结果表明,乳化剂的用量为6.5mM、PS/HD质量比为1/4时,聚合反应稳定。以PVAc为种子可以得到Janus结构的复合微球;以PSt为种子可以得到核壳结构的复合微球。进一步采用溶剂去除PS核和皂化反应将PVAc水解,得到了中空结构的PVA微球和Janus型双亲性PS/PVA微球。     

Co/Co_9S_8/ZnO核壳结构纳米微球的制备与表征

在无水无氧条件下通过热分解还原制备Co纳米微粒,利用Co9S8和ZnO晶格的相匹配性,通过层层自组装对Co表面进行修饰,得到Co/Co9S8/ZnO核壳结构纳米微球.采用XRD、TEM、SQUID、光致发光光谱(PL)等对产物进行了表征.通过调节反应参数制备出核壳结构的Co/Co9S8/ZnO复合纳米微球,平均粒径58.8nm,壳层厚度均匀,常温下显示铁磁性,矫顽力为18.7kA/m.PL表明,产物在380~390nm处的带边跃迁不明显,光致发光最强峰在468nm处,属氧缺陷发射峰,研究了影响产物形貌的主要因素.结果表明,以油酸(OLA)及三正辛基氧化磷(TOPO)为溶剂和表面活性剂,Zn(acac)2温度为70℃、用量为1mmol,控制Co的硫化反应时间为5min,有利于核壳结构产物的形成.初步分析了Co/Co9S8/ZnO核壳结构纳米微球的形成机理.     

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.     

聚苯乙烯/纳米金刚石复合微球的制备及性能测定

以纳米金刚石为乳化剂,BPO为引发剂,利用Pickering效应成功合成得到了聚苯乙烯/纳米金刚石复合微球.XRD、TDA-DTA、TEM、BET以及FT-IR分别进行了结构表征.研究结果表明,在聚苯乙烯/纳米金刚石复合微球中,纳米金刚石晶体为立方相,聚苯乙烯为无定形态,颗粒径粒大约为40～70nm,分散较好,比较面积达到230m2/g,该复合材料具有良好热稳定性.进一步的力学系性能测定表明,随着聚苯乙烯/纳米金刚石复合微球添加应用,聚苯乙烯的拉伸强度、断裂伸长率性能得到了明显地改善,但弯曲强度性能有所下降.     

分散聚合法制备二氧化硅/ 聚苯乙烯单分散复合微球

在醇/ 水混合介质中用分散聚合方法制备二氧化硅/ 聚苯乙烯单分散复合微球。探讨了分散聚合法制备无机/ 有机复合微球的过程, 考察了分散聚合反应的动力学过程。SEM 和TEM 观察结果表明: 在醇/ 水混合介质中, 用PVP K-30 作为稳定剂, 用分散聚合法制备了单分散的以二氧化硅为核、聚苯乙烯为壳的复合微球,成功实现了聚苯乙烯对二氧化硅的包覆, 复合微球的平均粒径为1.25μm , 分散系数ε为0.035 , 达到了单分散水平。还考察了稳定剂的浓度对复合微球粒径的影响, 当稳定剂PVP K-30 浓度增加时, 发现微球的粒径有所减小, 而微球的单分散性提高。      

聚合物中空微球的制备及粒径控制EI北大核心CSCD

采用种子乳液聚合法制备了高羧基含量的多层核/壳聚合物微球,然后用氨水对其进行碱处理,形成了粒径均一且内部具有空腔结构的聚合物微球。通过傅里叶变换红外光谱仪对核壳微球上的官能团进行分析;结合电导滴定曲线及Zeta电位值对聚合物微球亲水核/疏水壳的结构进行确定。研究了乳化剂十二烷基硫酸钠(SDS)用量和碱处理过程中的碱酸摩尔比对微球粒径及形貌的影响。结果表明,核、多层核/壳和聚合物中空微球的粒径及空腔直径均随SDS用量的增加而减小;碱酸摩尔比的增加有利于聚合物微球体积的膨胀,所得中空微球粒径及空腔直径均随碱酸摩尔比的增加而增大。控制乳化剂用量为0.01~0.03 g,碱酸摩尔比为1.0~2.0,可制得粒径为355~790 nm、空腔为118~450 nm的聚合物中空微球。     

聚苯乙烯-SiO2/NiFe2O4磁性微球的制备与表征

以NiFe2O4纳米粒子作磁性载体、苯乙烯(ST)、正硅酸乙酯(TEOS)为原料,KH-570为交联剂,采用乳液聚合法制备了聚苯乙烯-SiO2/NiFe2O4磁性微球材料。通过VSM、FT-IR、SEM、TG-DTA、溶剂抽提等方法对磁性微球材料进行了测试。制备的NiFe2O4粒子为面心立方结构,NiFe2O4纳米颗粒及聚苯乙烯-SiO2/NiFe2O4磁性微球具有超顺磁性。聚苯乙烯-SiO2/NiFe2O4磁性微球以SiO2/NiFe2O4为核、PS为壳,通过KH-570接枝到SiO2/NiFe2O4上,核壳间以共价键相接的包覆型纳米粒子,平均直径为100nm左右,具有良好的热稳定性和耐溶剂性能。热重(TG)分析表明,磁性聚苯乙烯微球磁性物质质量分数为28.8%。     

Facile route for preparation of silica-silver heterogeneous nanocomposite particles using alcohol reduction method

Silica-silver heterogeneous nanocomposite particles were successfully prepared by facile route including alcohol reduction method. Thiol groups were employed as a chemical protocol to make a binding between silver nanoparticle and silica surface. After the reaction for 10 min, a large number of quasi-spherical silver nanoparticles with an average size of 6.9 nm in diameter were homogeneously formed on the surface of silica particles. The immobilized silver nanoparticles grew to large ones with an average size of 10.6 nm in diameter after additional reaction for 2 h. The resulting nanocomposite particles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), UV-vis spectrophotometer, and X-ray diffraction (XRD) analysis.     

FeNi@SiO2磁性纳米复合粒子的制备及磁热性能

大量制备磁热性能优异的磁性纳米粒子对磁热疗和组织复温的生物学应用具有理论价值.本研究通过高温电弧法制备FeNi磁性纳米颗粒,通过超声-沉降分级筛分得到平均粒径为80 nm的FeNi纳米颗粒,通过溶胶-凝胶法得到平均粒径为100 nm,SiO2壳层厚度为15～20 nm的FeNi@SiO2纳米复合粒子.超导量子干涉仪测定...     

纳米镍/介孔二氧化硅复合材料的组装及结构和性质 Ⅰ : 纳米镍/介孔二氧化硅复合材料的制备及结构表征

利用介孔组装,可以进行纳米复合材料结构和功能设计。通过溶胶-凝胶方法,采用混合、浸泡和氢热还原工艺,获得纳米镍/介孔二氧化硅复合材料。运用DSC、XRD、XPS、TEM等手段对纳米镍/介孔二氧化硅复合材料进行表征。结果表明,纳米金属Ni颗粒的尺寸由介孔SiO₂的结构和孔径分布决定,受还原温度和成分等影响,在8~20nm范围变化,浸泡法更容易获得纳米金属颗粒均匀分布的复合材料。由于SiO₂介孔结构连通,纳米Ni表面存在氧化,纳米颗粒存在于介孔中形成壳结构。介孔二氧化硅基体中添加稀土元素Ce,有利于增强介孔基体骨架强度,限制纳米颗粒聚集长大。      

Sonochemical preparation of silica nanorods for gene delivery using single-walled carbon nanotubes as templates

Silica nanorods were fabricated with single-walled carbon nanotubes (SWCNTs) via ultrasound. The diameter of the resulting SWCNT-silica particles ranged from 60 to 70 nm. The morphology of this composite material was investigated via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The individual SWCNTs are uniformly coated with silica and formed a unique nanocomposite material. The important role of ultrasound and the mechanism of silica layer formation on SWCNTs were explained via the hydrolysis of the silica source and the adsorption of the siloxane groups on the SWCNT surfaces under ultrasound irradiation. The amino-functionalized silica nanorods were demonstrated as non-viral vectors for gene delivery.     

Proton conductivity of Nafion/ex situ Stöber silica nanocomposite membranes as a function of silica particle size and temperature

In the first systematic study of the influence of the size of silica particles on ion exchange capacity (IEC) and proton conductivity of Nafion–silica nanocomposite membranes, thin films cast from mixtures of silica particles (5 wt%) with varying diameters ranging from 10 to 400 nm and Nafion in alcohol were examined. IECs decreased exactly as expected with the dilution of Nafion and its sulfonic acid groups with added silica. At 80 °C, the proton conductivity was also less with silica particles. However, at higher temperatures (120 °C), there was a 58 % improvement in proton conductivity at low relative humidity and a 45 % improvement at higher relative humidity for nanocomposite membranes prepared with silica particles <50 nm in size. The improvement was less significant with larger silica particles in the membranes.     

Composite formation of Thiol-capped Au nanoparticles and mesoporous silica prepared by a sol-gel method

We have previously reported the fabrication of a nanocomposite from dodecanethiol-capped Au nanoparticles (average diameter 2.6 nm) and a silica aerogel. It was found that the Au particles were efficiently adsorbed on a silica wet-gel in organic solvents. In this paper, surface analysis of the silica surface and evaluation of adsorption rates for various solvents, performed to elucidate the nature of the interaction between the capped nanoparticles and the silica gel, are described. These observations indicate that dipole-induced dipole interaction between OH groups on the silica surface and metal cores of the nanoparticles is probably important for the adsorption. It was demonstrated that, by changing the solvent polarity, spatial distribution of the nanoparticles inside the gel can be controlled.     

Silica/Perfluoropolymer nanocomposites fabricated by direct melt-compounding: a novel method without surface modification on nano-silica

A novel method for the fabrication of silica/perfluoropolymer nanocomposites was investigated, whereby nano-sized silica particles without surface modification were dispersed uniformly through mechanical breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages. The first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, poly(tetrafluoroethyleneco-perfluoropropylvinylether), with the loose silica agglomerates prepared in the first stage. In the first stage, the packing structure and the fracture strength of the silica agglomerate were controlled by destabilizing an aqueous colloidal silica solution with a mean primary diameter of 190 nm via pH control and salt addition. In the next stage, the silica/perfluoropolymer nanocomposite was fabricated by breaking down the prepared loose silica agglomerates with low fracture strength by means of a shear force inside the polymer melt during melt-compounding.     

Fabrication of nanocomposite particles with superparamagnetic and luminescent functionalities

A new kind of superparamagnetic luminescent nanocomposite particles has been synthesized using a modified Stöber method combined with an electrostatic assembly process. Fe₃O₄ superparamagnetic nanoparticles were coated with uniform silica shell, and then 3-aminopropyltrimethoxysilane was used to terminate the silica surface with amino groups. Finally, negatively charged CdSe quantum dots (QDs) were assembled onto the surface of the amino-terminated SiO₂/Fe₃O₄ nanoparticles through electrostatic interactions. X-ray diffraction (XRD), transmission electron microscopy (TEM), microelectrophoresis, UV-vis absorption and emission spectroscopy and magnetometry were applied to characterize the nanocomposite particles. Dense CdSe QDs were immobilized on the silica surface. The thickness of silica shell was about 35 nm and the particle size of the final products was about 100 nm. The particles exhibited favorable superparamagnetic and photoluminescent properties.     

Preparation and characterization of polyimide/silica nanocomposite spheres

Silica (SiO₂) nanocomposite spherical particles coated with polyimide had been synthesized by a dispersion polymerization method. The chemical structure of polyimide/silica (PI/SiO₂) nanocomposite spherical particles was investigated by using FT-IR, and the surface morphology characterization was performed with SEM. The TEM showed that SiO₂ core was surface-coated with a multilayer composite and the multilayer thickness was about 20 nm. Moreover, the particles were homogeneously distributed and interconnected very fine. Basing the results, it was found that the PI/SiO₂ nanocomposite particles were core–shell structure.     

Influence of Egyptian nanoilmenite/amorphous silica composite particles on the electrochemical and mechanical properties of cold galvanizing formulation coatings

In the present work, Egyptian ilmenite nanoparticles (FeTiO₃ NPs) were obtained with the average diameters of 20?nm by a direct solid-phase milling process and synthesized amorphous silica powder grains were processed to prepare a novel fabricated Egyptian nanoilmenite/amorphous silica composite (ENI/AS) particles. Flaky-like nature of ENI/AS and the spherical shape of Zn-dust particles were emphasized by scanning electron microscopic (SEM) micrographs. The nano features of ENI/AS particles were confirmed by transmission electron microscope (TEM) investigation. Various alkyd-based cold galvanizing coating formulations were modified using different uniformly dispersing amounts of the processed ENI/AS particles as a modifier to form some nanocomposite coatings. The electrochemical behavior of nanocomposite modified coated steel films in oil-wells formation water solution have been studied by both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The mechanical properties of the coated films were studied through some coating tests as cross-cut adhesion, bend and impact to assert their application efficiency. Scanning electron microscope (SEM) technique was utilized to survey the protective film formed on the carbon steel surface by these modified coatings in formation water solution. The results of this study reinforced remarkable corrosion protection properties of ENI/AS modified cold galvanizing coating.