SYNTHESIS AND PROPERTIES OF POLYSTYRENE／LAPONITE NANOCOMPOSITES

Exfoliated polystyrene (PS)/laponite nanocomposites were prepared successfully. The characteristic doo1 diffraction peak of organo-laponite disappeared in the XRD patterns of nanocomposites, indicating that the laponite layers were exfoliated and the ordered crystal structure of laponite was destroyed because of the styrene polymerization. TEM observations showed that the exfoliated laponite primary particles were dispersed randomly in the PS matrix with lateral dimensions from 1 nm to 10 rim. SEM results showed that the PS/laponite nanocomposite particles were almost monodispersed spheres with the size of about 120 rim. Because of the interaction between PS and laponite nanolayers, the nanocomposites exhibited higher thermal stability and glass transition temperature when compared to pure PS.     

Synthesis of monodispersed organic-inorganic hybrid spheres

This paper describes the attempt to prepare a new group of monodispersed silica-polymer hybrid particles, which consists of silica and amide polymer: poly(vinylpyrrolidone) (PVP) and poly(2-ethyloxazoline) (POXZ). Preparation method is based on the growth of hybrid seeds by the addition of TEOS-polymer solution.Monodispersed PVP-silica hybrid particles of 1.24 µm in diameter were prepared by growing the hybrid seeds of 0.54 µm by the addition of TEOS-PVP solution with ammonia catalyst. In the case of POXZ-silica particles, addition of TEOS-POXZ solution to the solution containing 0.54 µm seeds resulted in monodispersed POXZ-silica hybrid particles and four times repetition of the addition for particle growth gave the hybrid particles of the diameter of 1.6 µm.Improvement of mechanical properties of hybrid particles was observed when the particles were heated at 100 200°C.     

Supramolecular Crystallization of Monodispersed Silica Spherical Particles (MSSP) in Concentrated Suspensions

The supramolecular crystallization of MSSP concentrated suspensions in alcohol and ethyl ether with various ammonia concentrations is found to occur as a phase transition, with appearence of a pre-transitional state. The temperature dependence of the time, it takes for this state to be established, evidences for the presence of processes of nucleation and activation character.     

单分散SiO2微球的制备及疏水改性研究

采用改进的凝胶-溶胶法制备了200~800 nm的单分散SiO2微球,并通过真空冷冻干燥法得到不易团聚的单分散SiO2粉体,采用乙醇超临界方法对制备的SiO2微球进行疏水改性.通过扫描电镜和氮吸附-脱附分析仪对SiO2微球的表面形貌、粒径以及孔径分布进行表征;用傅里叶红外变换测试和测量接触角对疏水改性的SiO2微球进行分析.结果表明SiO2微球粒径随二次加入TEOS体积增加呈先增大后减小.经过乙醇超临界处理,SiO2微球表面成功接枝上了疏水烷基,微球尺寸越小,疏水性越好,其接触角高达149°,单次SiO2微球处理量对结果无明显影响.采用本方法可以单次处理12 g以上的SiO2微球,接触角均在140°左右,可充分满足实验室使用需求.经过真空冷冻技术和乙醇超临界技术得到疏水单分散SiO2微球粉体,具有不易团聚及单分散性良好的优点,能够作为胶体晶体原料和三维有序材料(3-DOM)模板剂进行广泛应用.     

无皂乳液聚合合成均分散PMMA微球

甲基丙烯酸甲酯;微波辐照;无皂乳液聚合合成均分散PMMA微球     

均分散球形氧化铕超细微粒的制备和表征

采用尿素分解法制备了均分散球形Eu(OH)CO~3·H~2O超细沉淀粒子,进一步在空气中750℃下焙烧4h,得到了均分散球形氧化铕超细微粒。考察了各种反应条件的影响,获得了最佳的制备条件。用XRD,IR,TEM,TG以及比表面测定等手段对样品进行了表征。     

Dispersion copolymerization of styrene and glycidyl methacrylate in polar solvents

Monodispersed copolymer microspheres consisting of styrene and glycidyl methacrylate have been prepared by dispersion polymerization. The effects of various polymerization parameters on the particle size and size distribution were systematically investigated. The initial solubility parameter of the system had a significant effect on the final particle size and size distribution. With decreasing initial solubility parameter, the particle size increased and the size distribution broadened. The particle size decreased with increasing stabilizer concentration, the amount of styrene in the monomer mixture, and decreasing initiator concentration. Received: 30 September 1998 Accepted in revised form: 10 December 1998     

Synthesis of halogenated monodispersed telechelic oligomers. III. Bistelomerization of allyl acetate with telogens which exhibit α, ω-di(trichloromethyled) end groups

The redox bistelomerization of allyl acetate with telogens which exhibit α, ω-di(trichloromethyled) end groups catalyzed by copper, iron salts, or a ruthenium complex led to monoadducts and telechelic oligomers. These diacetates were quantitatively changed into diols. Such compounds have been characterized by both ¹H- and ¹³C-NMR. A reactivity series has been determined and shows that both end groups must be activated to obtain the expected telechelic products in satisfactory yields.     

表面附聚薄壳型单分散高效阳离子柱填料的研制及其性能

 报道了一种新的表面附聚薄壳型阳离子柱填料的简易制备方法。首次合成了单分散高效阳离子柱填料。以10μm的单分散聚苯乙烯 二乙烯基苯(PSTDVB)微球为基球,对其表面季铵化,然后均匀附聚一层磺化的阳离子乳胶(0 2μm),即得到阳离子固定相。分别用碱金属及碱土金属离子对用该填料制成的柱的性能进行了测试,结果表明该柱填料对常见阳离子具有很好的分离效果、良好的重现性和低的检测限。     

Nd‐Doped TiO2 Nanorods: Preparation and Application in Dye‐Sensitized Solar Cells

Monodispersed Nd‐doped TiO₂ nanorods (20 nm×2 nm) were synthesized by solvothermal methods and characterized by TEM, XRD, and EDS. Application of the nanorods for modifying conventional photoanodes in dye‐sensitized solar cells (DSSCs) was investigated. Data show that, after modification, an enhancement of the incident‐photon‐to‐current conversion efficiency (IPCE) in the whole range of visible light was observed and an increase of 33.3 % for overall conversion efficiency was achieved. Our mechanistic proposal is that Nd ions doped on TiO₂ nanorods to some extent enhance the injection of excited electrons and decrease the recombination rate of the injected electrons.