Optical properties of colloidal crystalline arrays composed of hollow polystyrene spheres

We have evaluated the optical properties of close‐packed and non close‐packed colloidal crystalline arrays made of hollow polystyrene spheres. Close‐packed colloidal crystalline arrays were fabricated by simple evaporation of dispersions, whereas nonclose‐packed colloidal crystalline arrays were fabricated by exploiting electrostatic interactions between the spheres in aqueous dispersion. Optical properties of the arrays were estimated from angle‐resolved reflection spectra. The Bragg diffraction peak of the colloidal crystalline array made of hollow spheres was of shorter wavelength than in the case of solid spheres, not only for the close‐packed array but also for the nonclose‐packed array. These shifts were caused by a decrease in the effective refractive index n_eff with decreasing particle refractive index. We have found that this relationship could be explained by the simple equation n_eff = n_particle?+ n_solvent (1 ? ?), where ? is the volume fraction of the particles, for both close‐packed and non close‐packed arrays. The current work suggests new possibilities for the creation of advanced colloidal crystals. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2364–2368, 2007     

Fabrication of Macroporous Alumina with Tailored Porosity

Macroporous alumina materials were fabricated via colloidal processing using polymer spheres as the template and ceramic particles as the building blocks. The influence of the suspension conditions and volume ratio of the polymer/ceramic particles on the formation of the pore structure has been investigated. The results showed that the suspension conditions have a significant effect on the pore morphology. A well-defined three-dimensional, ordered porous structure with a controllable pore size and porosity could be obtained through the hetero-coagulation, self-assembled processing of the polymer/ceramic particles. The pore size and porosity could be easily tailored by varying the polymer size and the volume ratio of the polymer/ceramic particles.     

Facile synthesis of Ag/AgBr/RGO nanocomposite as a highly efficient sunlight plasmonic photocatalyst

Well-dispersed Ag/AgBr colloidal spheres and the corresponding reduced graphene oxide (RGO) hybridized nanocomposite, Ag/AgBr/RGO, were synthesized by a simple one-step polyolthermal method. By rational tuning the synthesis conditions such as the content of polyvinylpyrrolidone (PVP), hexadecyltrimethyl ammonium bromide (CTAB), and the initial reaction temperature, the morphology, size and dispersity of the Ag/AgBr products can be easily controlled. The formation mechanism of as-prepared Ag/AgBr colloidal spheres was further proposed. The hybridization of Ag/AgBr spheres with RGO enhanced the composite catalytic performance, and the Ag/AgBr/RGO hybrid exhibited excellent catalytic activity and stability towards decomposition of Rhodamine B (RhB) under sunlight irradiation.     

聚乙二醇对碳纤维电极材料性能的影响

以聚乙二醇为改性剂,采用静电纺丝法制备聚丙烯腈纤维。经预氧化、碳化过程制备了聚丙烯腈基碳纤维。用SEM、XRD等手段表征了碳纤维的微观形貌及结构。用XPS测试表征了碳纤维表面元素含量。用循环伏安测试法测试碳纤维电极材料的电化学性能。实验结果表明,当聚乙二醇加入量为4％时,得到的碳纤维电极材料电容性能最佳,其比电容值达到126．84F／g。     

Cationic polystyrene spheres for removal of anionic contaminants in white water of papermaking

In a paper mill's water circuit, normal runnability of the paper machine is often disturbed due to the buildup of dissolved and colloidal substances (DCS). Contaminant adsorption on a solid adsorbent in a fluidized bed reactor has been applied for white water treatment. In the present study, polystyrene (PS) spheres were firstly acylated by acryloyl chloride, then poly(methacryloxyethyltrimethyl ammonium chloride) (PMAC) was grafted onto the acylated PS spheres, induced by surface‐initiated free‐radical polymerization. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and scanning electron microscopy were used to characterize the changes of PS spheres in chemical structures and surface morphology. The results showed that acylated PS spheres could be easily grafted with PMAC in 53.83% weight increase. Polyelectrolyte loading of PS spheres reached up to 1.72 mmol/g. The resulted cationic modified PS spheres could effectively decrease the cationic demand in white water and it still maintained high performance after operating repeatedly for 10 batches. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 10.1002/app.41379.     

Analysis of the structural parameters of polyacrylonitrile fibers containing nanohydroxyapatite

The structural parameters and strength properties of a new generation of polyacrylonitrile fibers have been analyzed. These fibers, after being carbonized, can be used in biomaterial engineering. They are characterized by a high tensile strength of 31–43 cN/tex. An advantageous influence of nanoparticles added to the fiber matter on the degree of crystallinity has been found. When nanoparticles of hydroxyapatite are incorporated into these fibers, their degree of crystallinity increases by about 5%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 760–765, 2006     

以聚苯乙烯为模板制备有序大孔氧化铝

采用少皂乳液聚合法成功制备了单分散的聚苯乙烯微球,以微球自组装后的聚苯乙烯胶体晶体为大孔模板,铝溶胶为前驱体填充模板,干燥焙烧除去模板后制备了氧化铝载体。用激光粒度仪、扫描电镜、X射线衍射和氮气吸脱附对聚苯乙烯胶体晶体和氧化铝载体进行了表征。结果表明:少皂乳液聚合法制备的聚苯乙烯微球具有粒径较小(100~350 nm)、单分散性好(0.005)、收率高(约80%)等优点;自组装的胶体晶体呈规则有序排列,微球表面光滑洁净,并以此为模板成功制备了具有三维有序结构的、大孔孔径可调的氧化铝材料。     

Effect of spinning conditions on the structure and properties of PAN fibers containing nano‐hydroxyapatite

Spinning conditions for nano‐hydroxyapatite‐containing precursor polyacrylonitrile (PAN) fibers have been developed and their effects on the structure and properties of nanocomposite PAN fibers have been assessed. The precursor PAN fibers prepared under the developed conditions are characterized by high strength, with their total pore content being at a level of 0.25 cm³/g. After carbonization, these fibers are designed for use as implants that support and stimulate the process of bone reconstruction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2881–2888, 2006     

Control of pit initiation sites on aluminum foil using colloidal crystals as mask

The electrochemical etching of aluminum foils using a physical mask of colloidal spheres was studied to directly control the initiation sites of pits independent of the surface activation state of the substrate. A two-dimensional array of colloidal spheres used as a mask was prepared by self-assembly on an aluminum substrate. The transfer of the hexagonally ordered pattern of self-assembled colloidal spheres to the aluminum substrate could be achieved by the selective electrochemical etching of an exposed aluminum surface. That is, etch pits were generated only in the triangular void space among the three spheres on the aluminum surface. Based on this process, the dispersibility of the initiation sites of pits was improved clearly in comparison with that for the conventional method. The density of pits could also be controlled by changing the diameter of spheres used as a mask.     

Effect of coagulation on the structure and property of PAN nascent fibers during dry jet wet-spinning

The paper has studied the effect of coagulation process on the structure and property of polyacrylonitrile nascent fibers during dry jet wet-spinning. The coagulation process to form polyacrylonitrile fibers has been studied by examination of FTIR, XRD, and SEM and so on. The results indicated that compared with coagulation directly, polyacrylonitrile nascent fibers gradually formed with fine crystallites and high degree of crystallization were achieved, the flex vibration peak of S=O gradually decreased, and less solvents remained in the nascent fibers with compact cross section morphology. At the same time, nascent fibers with less DMSO under different draw ratios showed higher fracture intensity and lower elongation.     

New Colloidal Lithographic Nanopatterns Fabricated by Combining Pre-Heating and Reactive Ion Etching

We report a low-cost and simple method for fabrication of nonspherical colloidal lithographic nanopatterns with a long-range order by preheating and oxygen reactive ion etching of monolayer and double-layer polystyrene spheres. This strategy allows excellent control of size and morphology of the colloidal particles and expands the applications of the colloidal patterns as templates for preparing ordered functional nanostructure arrays. For the first time, various unique nanostructures with long-range order, including network structures with tunable neck length and width, hexagonal-shaped, and rectangular-shaped arrays as well as size tunable nanohole arrays, were fabricated by this route. Promising potentials of such unique periodic nanostructures in various fields, such as photonic crystals, catalysts, templates for deposition, and masks for etching, are naturally expected.     

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。     

垂直沉积法制备SiO_2胶体晶体及其光子带隙特性

采用stober法在乙醇介质中合成S iO2微球,将制得的样品在30℃下用双氧水浸泡处理48 h。扫描电子显微镜(SEM)测定结果表明,样品平均粒径为292 nm,平均标准偏差小于5%。傅里叶红外光谱(FTIR)测定表明,经双氧水浸泡处理后,S iO2微球表面的羟基数目增多。Zeta电位和标准氢氧化钠滴定测试结果显示,经双氧水浸泡处理后,S iO2微球在水溶液中的Zeta电位从-55.72 mV提高到-63.26 mV,表面电荷密度从0.19 uC/cm2提高到0.28 uC/cm2。用垂直沉积法制备出有序性较好的密排结构的S iO2胶体晶体。在SEM下,观察到这种胶体晶体是面心立方(fcc)密排结构,其(111)晶面平行于基底。透射光谱表明,所制备的胶体晶体在(111)方向具有光子晶体的带隙性质。     

Influence of chromophoric electron-withdrawing groups on photoinduced deformation of azo polymer colloids

This study investigated the influence of chromophoric electron-withdrawing groups on photoinduced deformation behavior of colloidal spheres of three azo polymers. The colloidal spheres were prepared by using the epoxy-based azo polymers (BP-AZ-CA, BP-AZ-CN, and BP-AZ-NT) through gradual hydrophobic aggregation of the polymers in THF-H₂O media. The colloidal spheres were controlled to have similar average sizes by adjusting both the polymer concentrations in the initial THF solutions and water-adding rates in the preparation processes. The colloids were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The colloid deformation was investigated by irradiating the colloidal spheres in solid state with a linearly polarized Ar⁺ laser beam (488 nm, 130 mW/cm²). For comparison, the colloids were also studied by irradiation with a polarized diode solid state laser beam (532 nm, 130 mW/cm²). Upon the light irradiation, all the colloidal spheres were elongated along the polarization direction of the laser beams. The electron-withdrawing groups showed significant influence on the colloid deformation behavior related with the response to the light irradiation. The colloid deformation was more efficiently induced by irradiation with the laser beams having the intermediate wavelengths between the λ_max and the absorption band tails of the azo chromophores. When the hydrophilic carboxylic group was used as the electron-withdrawing groups, more significant deformation was induced under the same light irradiation condition, which could be attributed to the higher hydrophilicity of the polymer. Above observations can lead to a better understanding of the photoinduced deformation mechanism of azo polymer colloids.     

Effect of DMSO/H2O coagulation bath on the structure and property of polyacrylonitrile fibers during wet‐spinning

The effect of coagulation bath condition on the structure and property of the nascent fibers and polyacrylonitrile fibers during wet‐spinning is studied. The best coagulation condition to produce polyacrylonitrile fibers has been found by examination of EA, XRD, SEM, and so on. The results indicated that when the coagulation bath was DMSO/H₂O system, the temperature was 60°C, the concentration was 65%, the minus stretch ratio was ?10%, fine crystallites and high degree of crystallization in the nascent fibers and polyacrylonitrile fibers could be achieved, and less solvents remained in the nascent fibers with circular cross section morphology. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

胶体模板法制备三维锗光子晶体

采用胶体模板法并通过简单可控的化学填充工艺制备了三维锗光子晶体;以单分散二氧化硅小球的蛋白石结构为模板,由氯化亚锗与丙烯酸化合制备得到3-三氯锗丙酸（Cl3GeCH2CH2COOH）白色粉末,以三氯锗丙酸的乙醇溶液作为锗源先驱体,低温水解得到β-羧乙基锗倍半氧化物,在600～660℃经H2还原后形成锗,由2％HF化学浸蚀消除模板．对终产物进行X射线衍射分析。结果表明：产物为多晶锗。通过扫描电子显微镜对终产物的形貌进行观察的结果表明：包裹有空气的锗壳球有序阵列已经形成。将先驱体浓度为0．6mol／L的溶液填入模板空隙后。壳层表面可以获得较为光滑致密的锗壳。     

A comparative structure–property study of polyphosphazene micro-nano spheres

Novel fluorinated cross-linked polyphosphazene micro-nano spheres have been prepared by precipitation polymerization of hexachlorocyclotriphosphazene (HCCP) monomer. The influence of molecular structure on the morphology of polyphosphazene micro-nano spheres was investigated by SEM and TEM. The micro-nano spheres were also characterized by Fourier transforms infrared, X-ray photoelectron spectroscopy and thermo gravimetric analysis. The results indicate that the 5 % thermal degradation temperature is 366 °C. It was found that a silicon wafer dip-coated with thus prepared micro-nano spheres has a water contact angle as high as 137° ± 1.5°. Furthermore, the effects of the concentration of HCCP and ultrasonic power on the morphology were also discussed.     

Interaction between polyacrylonitrile and alkalis

Interactions between highly isotactic acrylonitrile homopolymers and alkalis in dimethyl sulfoxide solvent were examined. Coloration occurred as soon as polyacrylonitrile was added to a dimethyl sulfoxide/alkali mixture. The effects of alkali on highly isotactic polyacrylonitrile were greater than those on ordinary polyacrylonitrile. The intrinsic viscosity of polyacrylonitrile decreased quickly with the addition of sodium ethoxide and sodium hydroxide, and the effect of sodium ethoxide was more prominent than that of sodium hydroxide. As the concentration of sodium ethoxide and sodium hydroxide went beyond 0.01 mol/L, the intrinsic viscosity showed a trend of increasing. Within the first half‐hour, there was a great drop in the intrinsic viscosity of highly isotactic polyacrylonitrile, and then the intrinsic viscosity appeared to increase. The intrinsic viscosity of highly isotactic polyacrylonitrile increased continuously with the addition of diethylamine along with time. The effects of alkalis on the tacticity of the polymers followed the order of the alkali strength. Diethylamine was more effective for moderating the stabilization exotherm of polyacrylonitrile than sodium ethoxide and sodium hydroxide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 272–275, 2006     

NiO纳米电池材料的制备及电化学性能研究

在200℃下用溶剂热的方式将醋酸镍热分解,引入PVP活性剂,得到由3～5nm厚的薄片组成的直径约为100nm NiO中空球,通过改变PVP的数量,完成了NiO组装线表面积从约70m2.g-1到约200m2.g-1的调整,对比实验表明NiO组装球表面积对其放电容量有显著的影响,电化学测试NiO中空球具有823mA’h/g的放电容量,而且这些中空球也显示慢的容量衰退速度。     

Catalyst-free synthesis of multi-walled carbon nanotubes from carbon spheres and its implications for the formation mechanism

A route to producing multi-walled carbon nanotubes (MWCNTs) was reported, in which polyacrylonitrile microspheres (PANMSs) were assembled into one-dimensional strings of carbon spheres and transformed to carbon nanotubes at 1000 °C. It was found that the diameters of the MWCNTs are uniform and correlated with the size of the PANMSs used. Structures of intermediate products obtained by stopping the reaction have been examined by high-resolution transmission electron microscopy. The observations indicate that the formation of MWCNTs follows a different mechanism from the well-studied vapor–liquid–solid mode. It involves a direct self-assembly and solid-state structural transformation of PANMSs under the promotion of nitrogen atoms as shown by the X-ray photoelectron spectra of the resulting samples. On the basis of these observations, a sphere-string-tube mechanism was proposed for the MWCNT formation.