Electrosynthesis of well-organized nanoporous poly(3,4-ethylenedioxythiophene) by nanosphere lithography

The electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) films from aqueous surfactant solution through a two-dimensional poly(styrene) (PS) template onto indium tin oxide (ITO) substrate has been investigated. The polymer grows in the interstitial spaces of the self-assembled PS spheres which were subsequently removed by dissolution in tetrahydrofuran (THF). Surface characterization by scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveals that two-dimensional nanoporous honeycomb PEDOT structures can easily be obtained by using PS spheres of different sizes. Gold electrodeposition onto the nanostructured PEDOT electrode was investigated and SEM images show preferential formation of nanoparticles (NP) on the wall and the rim of the PEDOT film but metal clusters inside the pores are also observed.     

Detection of free surface composition and molecular-level structural development of styrene(S)/butadiene(B) block copolymer films during a solution-to-film process

The surface chemical structure development in solution-cast styrene(S)/butadiene(B) block copolymer films as a function of solvent evaporation time was investigated using sum frequency generation vibrational spectroscopy(SFG).The surface structure formation of the styrene(S)/butadien(B) block copolymer(30 wt% PS) films during the solution-to-film process was found to be controlled mainly by dynamic factors,such as the mobility of the PB block in solution.For SB diblock copolymers,a pure PB surface layer was formed only when the film was cast by dilute toluene solution.With increasing concentration of casting solution,PB and PS components were found to coexist on the film surface,and the morphology of the PB component on the film surface changed from cylindrical rods to spheres.For SBS triblock copolymers,a small amount of PS component existed on the surface even if the film was cast by 1.0 wt% toluene solution.In addition,PS components at the outermost layer of the film increased and the length of PB cylindrical rods on the surface decreased with increasing concentration of casting solution.     

In situ synthesis of sulfide-coated polystyrene composites for the fabrication of photonic crystals

Sulfide (CdS, ZnS, and SnS(2))-coated polystyrene (PS) nanocomposites with a diameter of about 160 nm were synthesized by an in situ synthesis method. The PS spheres adsorbed polyelectrolytes, which were coordinated with Cd(2+) and Zn(2+) reacted with sulfions released through the hydrolysis of thioacetamide in an aqueous bath. As to the SnS(2)-coated PS composite, we introduced a deposition method in which a thin layer of SnS(2) was deposited on the surface of PS spheres. The PS spheres assembled on the patterned substrate of porous aluminum oxide (PAO) were more regular than those on the nonpatterned microslide, so the PS spheres coated with CdS and ZnS composites were assembled into ordered arrays on the PAO substrate, respectively. And the obtained lambda(max) of CdS-coated PS colloid crystal array red-shifted 262 nm compared with that of the pure PS colloid crystal array. All the particles and colloid crystal arrays were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) was undertaken to determine the elements Cd, S, and Sn.     

Urea Biosensor Based on Electrochromic Properties of Prussian Blue

Prussian blue (PB) is an electrochromic material, which can be used as a signal transducer in the formation of optical urea biosensors. The previous researches in electrochromic properties of PB demonstrated the optical PB response to ammonium ions, which occurs when ammonium ions are interacting with PB layer at a constant 0.2 V vs Ag|AgCl|KCl_sat potential. In this work PB optical dependence on ammonium ions concentration was applied in the formation of electrochromic urea biosensor. Biosensor was formed by modifying the optically transparent indium tin oxide (ITO) coated glass electrode (glass/ITO) with Prussian blue layer and immobilizing urease (glass/ITO/PB‐urease). Calibration curve showed the linear dependency (R²=0.995) between the change of maximal absorbance (ΔA) and urea concentration in concentration range varying from 3 mM to 30 mM. The highest sensitivity (4 ΔA M^?1) of glass/ITO/PB‐urease biosensor is in the concentration range from 7 mM to 30 mM. It was determined that working principle of the glass/ITO/PB‐urease biosensor is not related to pH changes occurring during enzymatic hydrolysis of urea.     

微接触印刷技术转移Au纳米粒子及氧化石墨烯复合图案及其性质研究

通过改良的“Hummers方法”制得氧化石墨烯,利用聚二甲基硅氧烷（PDMS）弹性印章的微接触印刷技术,以Au膜和氧化石墨烯溶液为“墨水”,通过二次印章转移,分别将Au纳米粒子和氧化石墨烯（Graphene Oxide,GO）转移至修饰了(3-氨基丙基)三乙氧基硅烷（APTES）的ITO基底（APTES/ITO）表面. 利用场发射扫描电子显微镜（FE-SEM）、原子力显微镜（AFM）等表征图案,结果表明转移的AuNPs和GO组成的复合图案均匀,致密性较好. 利用表面电势显微镜（Surface Potential Microscope,SEPM,KFM）测定了各部分的表面电势,以APTES/ITO基底表面为表面电势零点,各部分表面电势大小为：APTES/ITO > GO > Au（0,-11.6,-44.2 mV）.     

Direct electrochemistry and electrocatalysis of reduced glutathione on CNFs-PDDA/PB nanocomposite film modified ITO electrode for biosensors

The electrochemical oxidation of reduced glutathione (GSH) catalyzed by electro generated Berlin green at carbon nanofibers-poly(diallyldimethylammonium chloride)/Prussian blue (CNFs-PDDA/PB) nanocomposite film modified ITO electrode has been studied. The CNFs-PDDA/PB nanocomposite film were fabricated by casting the composite CNFs enfolded PDDA on ITO electrode followed by electrochemical deposition of PB on the CNFs-PDDA matrix using cyclic voltammetry (CV). Electron microscopy (TEM, AFM), and Fourier transform infrared spectroscopy (FT-IR) studies were used to characterize the morphology and structure of the nanocomposite. The fabricated CNFs-PDDA/PB/ITO nanocomposite film electrode shows significant improvement of redox activity of PB due to the excellent electron transfer ability of CNFs. It was also found to possess prominent electrocatalytic activity toward the oxidation of glutathione with high sensitivity as high as 2.07 μA dm(3) mol(-1) cm(-2). A nontoxic, stable and convenient method for the detection of GSH in the concentration range of 6.0×10(-6) to 1.74×10(-5) M has been developed and it showed improved sensor performance compared to the unmodified PB electrode. The high sensitivity, wider linear range, good reproducibility, and the minimal surface fouling make this CNFs/PDDA/PB nanocomposite film a promising candidate for GSH sensors.     

Patterned assembly of colloidal particles by confined dewetting lithography

We report the assembly of colloidal particles into confined arrangements and patterns on various cleaned and chemically modified solid substrates using a method which we term "confined dewetting lithography" or CDL for short. The experimental setup for CDL is a simple deposition cell where an aqueous suspension of colloidal particles (e.g., polystyrene spheres) is placed between a floating deposition template (i.e., metal microgrid) and the solid substrate. The voids of the deposition template serve as an array of micrometer-sized reservoirs where several hydrodynamic processes are confined. These processes include water evaporation, meniscus formation, convective flow, rupturing, dewetting, and capillary-bridge formation. We discuss the optimal conditions where the CDL has a high efficiency to deposit intricate patterns of colloidal particles using polystyrene spheres (PS; 4.5, 2.0, 1.7, 0.11, 0.064 microm diameter) and square and hexagonal deposition templates as model systems. We find that the optimization conditions of the CDL method, when using submicrometer, sulfate-functionalized PS particles, are primarily dependent on minimizing attractive particle-substrate interactions. The CDL methodology described herein presents a relatively simple and rapid method to assemble virtually any geometric pattern, including more complex patterns assembled using PS particles with different diameters, from aqueous suspensions by choosing suitable conditions and materials.     

Surface-guided self-assembly of silver nanoparticles on edges of heterogeneous surfaces

A general method for the generation of two-dimensional (2D) ordered silver nanoparticles (av 45 nm) ring array has been demonstrated via controllable self-assembly. The selective self-assembly is conducted on the edges of a gold coated polyelectrolyte film. This film is fabricated using the monolayer polystyrene (PS) spheres (av 600 nm) on a substrate as template, followed by depositing a positively charged polyelectrolyte and gold colloids (av 17 nm) via the layer-by-layer (LbL) self-assembly technique, and finally by eliminating the PS monolayer. This gold coated polyelectrolyte film has a regular pattern of sharp edges, and those edges are composed of abundant polyelectrolyte. This heterogeneous surface is easily prepared and universal for site-selective absorption of nanoparticles (silver nanoparticles in this paper, av 45 nm). This surface-guided self-assembly is powerful for fabricating micro/nanostructures on the edges of prepatterns. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the products.     

Solvent Induced Sphere Development in Symmetric Diblock Copolymer Thin Films

Summary: We follow the time development of the microdomain structure in symmetric polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) diblock copolymer thin films during acetone vapor treatment. Besides the highly ordered nanoscopic spheres or stripes as reported previously, a novel so‐called flower‐like pattern, which comprises six PS spheres and each PS sphere belongs to three “flowers” is formed. This finding is very helpful to discuss the highly ordered nanoscopic sphere formation process.

Transition from flower‐like structure to well‐ordered arrays of spheres, in which the flower‐like pattern, the transitional morphology, and the ordered spheres are in the portion A, B, and C, respectively.     

悬浮液气-液界面二元胶体颗粒的漂浮组装机理

提出一种在悬浮液气-液界面漂浮组装亚微米单分散聚苯乙烯(PS)微球和纳米SiO2颗粒二元胶粒晶体的新方法, 并系统研究了漂浮组装机理. 研究表明, 聚苯乙烯微球和二氧化硅两种胶体颗粒在悬浮液气-液界面的漂浮组装是以PS微球的组装为主导的. 在一定PS微球相浓度范围内, 悬浮液中PS 微球与SiO2颗粒的初始体积配比基本不影响PS微球有序组装的形成. PS微球粒径在150-500 nm时易于形成有序排列, 较小或较大粒径的PS微球难以形成有序排列. SiO2颗粒的组装是一种以PS微球为“基底”的沉积过程. 二元胶粒晶体中SiO2颗粒的体积分数由其在混合悬浮液中的相浓度所决定.     

New high impact polystyrene: Use of poly(1‐hexene) and poly(1‐hexene‐co‐hexadiene) as impact modifiers

In this study, polystyrene (PS) was melt blended with different amounts of poly1‐hexene (PH) and poly(1‐hexene‐co‐hexadiene) (COPOLY) and the blends were compared with conventional PS/polybutadiene (PS/PB) one. Scanning electron microscope revealed that the dispersion of PH and COPOLY in PS matrix was more uniform with the appearance of small particles in PS matrix; however, in the case of PS/PB blends, the fracture surface showed nonhomogenous morphology with the appearance of bigger rubber particles. Based on Differential Scanning Calorimetry (DSC) and dynamic mechanical thermal analysis results, T_g of the blends decreased in comparison with it in neat PS. Impact strength of PS/PH and PS/COPOLY blends was considerably higher than that in PS/PB and significantly higher than the value for neat PS. Tensile test showed substantial improvement in stress at yield and better elongation at break for COPOLY containing blend than the samples containing PH and PB rubbers. Also, blending of PS with 10% of the rubbers was considered in the presence of dicumylperoxide as a probable grafting/cross‐linking agent to produce XPS/COPOLY10 and XPS/PB10 samples, respectively. IR results of the nonsoluble solvent extracted gel showed that COPOLY and PB were grafted to PS matrix during melt blending, which caused higher impact strength in the related samples.     

Electrochemical quartz crystal microbalance study on the two-electrode-system cyclic voltammetric behavior of Prussian blue films

A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.     

Glass transitions and mixed phases in block SBS

Differential scanning calorimetry (DSC) does not allow for easy determination of the glass‐transition temperature (T_g) of the polystyrene (PS) block in styrene–butadiene–styrene (SBS) block copolymers. Modulated DSC (MDSC), which deconvolutes the standard DSC signal into reversing and nonreversing signals, was used to determine the (T_g) of both the polybutadiene (PB) and PS blocks in SBS. The T_g of the PB block was sharp, at ?92 °C, but that for the PS blocks was extremely broad, from ?60 to 125 °C with a maximum at 68 °C because of blending with PB. PS blocks were found only to exist in a mixed PS–PB phase. This concurred with the results from dynamic mechanical analysis. Annealing did not allow for a segregation of the PS blocks into a pure phase, but allowed for the segregation of the mixed phase into two mixed phases, one that was PB‐rich and the other that was PS‐rich. It is concluded that three phases coexist in SBS: PB, PB‐rich, and PS‐rich phases. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 276–279, 2005     

Hydrothermal Synthesis and Field Enhancement Behavior of ZnO Nanorods Pattern

We provide a new way to prepare ZnO nanorods pattern from the solution composed of hexamethylenetetramine (HMT) and Zn(NO₃)₂. The substrate is ITO substrate covered by well ordered Au islands. Since Au and the underneath ITO substrate have two different nucleation rates in the initial stage of heterogeneous nucleation process, the subsequent ZnO growth on the quick nucleating area takes place under diffusion control and is able to confine the synthesis of ZnO nanorods to specific locations. The concentrations of zinc nitrate and HMT are well adjusted to show the possibility of the new route for the patterning of the ZnO nanorods. Furthermore, the nanorods pattern was characterized by X-ray diffraction and photoluminescence and the performance of field emission property from ZnO nanorod patterns was investigated. The ZnO nanorods pattern with a good alignment also shows a good field enhancement behavior with a high value of the field enhancement factor.     

Synthesis of an amphiphilic styrenic block copolymer: Polycondensation of dichloromethane and low molecular weight poly(ethylene glycol) in the presence of hydroxypropylated polystyrene‐block‐polybutadiene

An amphiphilic styrenic block copolymer, polystyrene‐block‐polybutadiene‐block‐poly[oxymethylene‐alt‐oligo(oxyethylene)] (PS‐b‐PB‐b‐POME), was synthesized through a polycondensation reaction of low molecular weight poly(ethylene glycol) and dichloromethane in the presence of hydroxypropylated polystyrene‐block‐polybutadiene (PS‐b‐PB‐OH) used as a monofunctional chain‐capping reagent. PS‐b‐PB‐OH was in turn prepared via an anionic synthesis of PS‐b‐PB followed by oxetane capping and methanol quenching. Although PS‐b‐PB‐OH has insignificant hydrophilicity, PS‐b‐PB‐b‐POME containing both the hydrophobic PS‐b‐PB segment and the hydrophilic POME segment had an improved emulsifying capability and effectively decreased the interfacial tension between water and toluene. The hydrophile–lipophile balance value of this amphiphilic PS‐b‐PB‐b‐POME copolymer, consisting of 86 wt % of the POME segment and 14 wt % of the PS‐b‐PB segment, was 17.2. The molecular weight of the copolymer molecule was determined by gel permeation chromatography–multi‐angle laser light scattering, and the microstructure was analyzed using ¹H NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2625–2632, 2001     

ITO pattern fabrication of glass platforms for electropolymerization of light sensitive polymer for its conjugation to bioreceptors on a micro-array

We present herein an effective and versatile method to fabricate a micro-patterned structure of conductive polymer, poly(pyrrole-benzophenone), on Indium Tin Oxide (ITO) glass chips for the subsequent photo-immobilization of various bioreceptor, antigens. Such methodologies are based on photolithography of ITO pattern fabrication on non-conductive surfaces, glass slides, and on a photo-active electrogenerated polymer films. The photo-active polymer serves as a substrate platform for the photo-immobilization of the bioreceptor reagents used for subsequent immunoreactions. We were able to show the resolution of electropolymerization on an ITO pattern as well as immobilization of more than one bioreceptor for the simultaneous detection of several analytes. The antigen micro-arrays were tested for sensitivity, specificity, and overall practicality for the simultaneous detection of analyte anti-Cholera Toxin B, anti-Hepatitis B virus surface and core protein antibodies. In addition we used our pattern ITO-poly(pyrrole-benzophenone) micro-array for the detection of serum samples of Hepatitis B virus patients previously screened by a standard hospital detection method.     

氧化铟锡(ITO)自组装修饰及其对有机电致发光器件性能的影响

设计合成了一种新型的有机硅氧烷Cz-Si,并将其用于ITO自组装修饰。制备的Cz-Si具有较好的稳定性,可以在空气中对ITO进行自组装修饰,实验操作简单。为考察ITO自组装修饰对有机电致发光器件性能的影响,分别以修饰后的ITO(ITO/SAM)及不修饰的ITO(unmodified)作阳极,制备了一系列有机电致发光器件ITO/SAM(or unmodified)/NPB(40~50 nm)/Alq₃(60 nm)/LiF(1.0 nm)/Al。实验结果表明,ITO自组装修饰后器件性能可以得到显著提升,研究认为这与其调控ITO/有机层界面的电子能级、粗糙度以及界面一致性有关。     

Fabrication of BaTiO3 Inverse Opal Photonic Crystal

The colloidal crystal template or opal with a closed-packed face centered cubic (fcc) lattice, was prepared from monodisperse polystyrene (PS) spheres by gravity sedimentation. The template was used for the generation of photonic crystal. The template provided void space for infiltration of liquid precursor composed of titanium butyloxide, barium acetate, ethanol, and acetic acid. The opal composite was hydrolyzed, dried, sintered by heating for completely removing PS spheres to form BaTiO3 photonic crystals with inverse opal structure. The PS spheres were replaced by air spheres, which interconnected each other through the windows on the BaTiO3 wall.So both the BaTiO3 wall and air void constitute continuous phases.     

Novel block–comb/graft copolymers with the macromonomer strategy and anionic polymerization

The following block–comb/graft copolymers of styrene (S), isoprene (I), and butadiene (B)—PS‐b‐(PB‐g‐PB), PS‐b‐(PB‐g‐PB)‐b‐PS, (PB‐g‐PB)‐b‐P2VP, (PS‐g‐PB)‐b‐(PI‐g‐PS), (PS‐g‐PB)‐b‐(PI‐g‐PS)‐b‐(PB‐g‐PI), (PS‐g‐PB)‐b‐(PI‐g‐PS)‐b‐(PB‐g‐PI)‐b‐(PI‐g‐PS)‐b‐(PS‐g‐PB), and (PS)₂(PB‐g‐PB) [where PS is polystyrene, PB is polybutadiene, P2VP is poly(2‐vinylpyridine) (2VP), and PI is polyisoprene]—were synthesized with the macromonomer strategy and anionic polymerization high‐vacuum techniques. The synthetic approach involves the synthesis and block copolymerization of styrenic macromonomers in situ without isolation. The prepared samples were characterized by size exclusion chromatography with a differential refractometer detector, size exclusion chromatography with a two‐angle laser light scattering detector, and NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4040–4049, 2005     

Ampholyte polystyrene spheres self-regulated deposition of noble metal nanoparticles for catalyst applications

The polystyrene (PS) spheres having dual functional groups were synthesized using emulsifier-free emulsion polymerization based on St/potassium persulfate/water system in the presence of V-50 as co-initiator. Fourier transform infrared (FTIR) confirms the presence of the sulfate and the amino groups on the surfaces of PS spheres. Transmission electron microscopy and X-ray photoelectron spectra revealed that the PS spheres were successfully deposited with catalytic palladium (Pd) or gold (Au) nanoparticles (NPs). The reduction of 4-nitroaniline to 4-phenylenediamine used as a model reaction was performed for catalysis studies and examined by ultraviolet. It was found that both Au and Pd PS dispersions show high catalytic activity. The Pd PS dispersion of 200 μl with only Pd content of 1.09 wt.% exhibits an excellent catalytic effect superior to the commercial Pd/C catalyst, i.e., less than 35 s taken for the completion of the reduction of 4-nitroaniline.