Electroless plating of honeycomb and pincushion polymer films prepared by self-organization

This report describes the fabrication and electroless plating of regular porous and pincushion-like polymer structures prepared by self-organization. Honeycomb-patterned films were prepared by simple casting of polymer solution under applied humid air and pincushion structures by peeling off the top layer of the former films. Silver-deposited honeycomb-patterned films and pincushion films were obtained by simple electroless plating of the respective original structures. XPS revealed Ag deposition on the honeycomb-patterned film. After thermal decomposition or solvent elution of the template polymer, unique metal mesoscopic structures were obtained.     

Fabrication of Ordered Arrays of Biodegradable Polymer Pincushions Using Self-Organized Honeycomb-Patterned Films

Nano- and micropatterned structures of tissue engineering scaffolds made of biodegradable and biocompatible polymers profoundly influence cell behavior. The present study describes a technically simple and inexpensive method to rapidly fabricate hexagonal arrays of biodegradable polymer pillars (pincushions). As precursors to these polymer pincushion arrays, highly regular porous biodegradable polymer films (self-organized honeycomb-patterned films, called honeycomb films) were prepared on a glass substrate using a simple casting technique. Scanning electron microscope observations revealed that the honeycomb film was composed of a top and bottom layer. This double-layered structure is attributable to the self-organization of hexagonally packed arrays of water droplets that form the template. When we peeled off the top layer of the honeycomb film under ambient conditions using adhesive tape, we obtained arrays of polymer pincushions on both side of the glass substrate and on the adhesive tape. Each air hole is surrounded by six pincushions, each with a diameter of 0.1-1 µm. We also studied factors that determine the morphology of the pincushions, such as the thermal and mechanical properties of the polymers used. It was shown that the heights, widths, and distances of separation between the pincushions could be controlled by the choice of polymer and the pore structure of the original honeycomb film. Such well-ordered, biologically inspired pincushion structures could find application in biomedical, photonic, and electronic materials.     

溶剂散逸自组装制备导电各向异性的金属有序阵列

通过溶剂散逸自组装法制备了聚苯乙烯(PS)有序多孔膜. 利用水珠在冷的PS溶液表面凝结形成有序阵列, 使PS以水珠阵列为模板形成有序多孔膜. 将有序多孔膜的上层剥离并附着在可收缩性高分子表面, 并进行离子溅射, 除掉有序多孔膜后在可收缩膜上留下了有序的金属圆盘阵列. 经过收缩, 有序阵列不仅光学性质发生了改变, 而且实现了导电的各向异性.     

Superhydrophobic and lipophobic properties of self-organized honeycomb and pincushion structures

This report describes the simple preparation of superhydrophobic and lipophobic surfaces by self-organization. Microporous polymer films of a fluorinated polymer with hexagonally arranged pores were prepared by casting from solution under humid conditions. Hexagonally packed water microdroplets were formed by evaporative cooling on the surface of the casting solution. After solvent evaporation, a honeycomb-patterned polymer film was formed with the water droplet array acting as a template; the water droplets themselves evaporated soon after the solvent. Two porous polymer layers were stacked vertically, separated by pillars at the hexagon vertexes. After peeling off the top layer using adhesive tape, a pincushion-like structure was obtained. Here, we show that superhydrophobic behavior was achieved, with the maximum contact angle, 170 degrees, observed using these pincushion structures. Theoretical calculations fit the experimental results well. The lipophobic properties of the films are also discussed.     

Mesoscale pincushions, microrings, and microdots prepared by heating and peeling of self-organized honeycomb-patterned films deposited on a solid substrate

We describe here a preparation of pincushion structures with holes, hexagonally arranged microrings, and microdots by simple heating and peeling of self-organized honeycomb-patterned films. We have reported that the honeycomb-patterned films can be prepared by casting the solution of an amphiphilic polymer and a hydrophobic polymer under humid conditions. When annealing the honeycomb-patterned films prepared from an amphiphilic copolymer and poly(bisphenol A carbonate), we obtained a variety of mesoscale structures, depending on the heating temperatures. We revealed that these microstructures were formed by using the phase-separation structures in the self-organized honeycomb-patterned films. These micropatterns can be utilized for the template for microelectrodes, superhydrophobic surfaces, photonic crystals, and as a substrate for tissue engineering.     

Nanoengineered multiscale hierarchical structures with tailored wetting properties

A simple method for fabricating micro/nanoscale hierarchical structures is presented using a two-step temperature-directed capillary molding technique. This lithographic method involves a sequential application of the molding process in which a uniform polymer-coated surface is molded with a patterned mold by means of capillary force above the glass transition temperature of the polymer. Various microstructures and nanostructures were fabricated with minimum resolution down to approximately 50 nm with good reproducibility. Also contact angle measurements of water indicated that two wetting states coexist on a multiscale hierarchical structure where heterogeneous wetting is dominant for the microstructure and homogeneous wetting for the nanostructure. A simple theoretical model combining these two wetting states was presented, which was in good agreement with the experimental data. Using this approach, multiscale hierarchical structures for biomimetic functional surfaces can be fabricated with precise control over geometrical parameters and the wettability of a solid surface can be tailored in a controllable manner.     

Polypyrrole electrodeposition on inorganic semiconductors CuInSe2 and CuInS2 for photovoltaic applications

Thin polypyrrole (PPy) layers with an average thickness of about 0.5 μm were deposited, using potentiostatic and galvanostatic techniques, on CuInSe₂ (CISe) structures prepared electrochemically on glass/ITO substrates and on CuInS₂ (CIS) structures fabricated on Cu tape substrates. The polymer layer of p-type is considered as an alternative to the traditional buffer layer and window layer in the conventional cell structure. The deposition proceeded from an aqueous solution containing sodium naphthalene-2-sulfonate as a dopant. In order to prepare stable PPy films of high quality with a good adherence to the surface of inorganic semiconductors CIS and CISe, the optimal concentrations of reagents, current densities and electrodepositing potentials were selected experimentally. Electrochemical polymerization of pyrrole to PPy on CIS surfaces is faster under white light irradiation and the polymerisation starts at lower potential than in the dark. Significant photovoltage and photocurrent of the fabricated CISe/PPy and CIS/PPy structures have been observed under standard white light illumination.     

Structure of a spin-crossover Fe(II)–1,2,4-triazole polymer complex dispersed in an isotactic polystyrene matrix

Isotactic polystyrene (i-PS) was employed as a matrix to disperse a metallo-organic polymer of [Fe(II) (4-octadecyl-1,2,4-triazole)₃(ClO₄)₂] in order to obtain novel functional materials exhibiting thermal spin-crossover transition. A detailed investigation of the structure of the metallo-organic polymer and metallo-organic polymer/iPS blends has been carried out by DSC, WAXD and SAXS techniques as a function of temperature and metallo-organic polymer/iPS proportion.The results obtained confirm on the one hand that a structural transition associated with a change in the magnetic susceptibility of the metallo-organic polymer is preserved in the presence of i-PS. This transition was found to be associated to both, an inter-conversion of lamellar structures into hexagonal structures and to an increase of inter-sheet distances within the lamellar structures in metallo-organic polymer films prepared by casting from toluene solutions. On the other hand, an increase of the degree of crystallinity of the iPS is observed in the presence of the metallo-organic polymer which suggests some nucleating effect of the metallo-organic polymer in the crystallization of isotactic polystyrene.     

Surface plasmon fluorescence investigation of energy-transfer-controllable organic thin films

Thin functional organic films on a gold substrate were fabricated by adsorbing tetrakis(carboxyphenyl)porphyrin (TCPP) on a spacer layer, which was prepared by the layer-by-layer adsorption of a dendrimer and a linear polymer. The thickness and photoluminescence of the films were investigated by surface plasmon resonance and surface plasmon fluorescence techniques, respectively. TCPP adsorbed on the spacer layer in aqueous solutions of different ionic strengths resulted in a thick TCPP adlayer at high ionic strength and a shrunk spacer layer at low ionic strength. The fluorescence was quenched at high ionic strength but could be observed at low ionic strength. The effects are explained by the states of dye aggregation. This study shows the control of energy transfer from a metal surface to a dye layer by changing the dye adlayer. It can contribute to the development of molecular devices involving energy-transfer systems.     

均苯型聚酰亚胺模塑粉的制备与性能

用含有扭曲非共平面结构的二胺1,3-二(3-氨基苯氧基-4'-苯酰基 )苯(BABB)与均苯四甲酸二酐(PMDA)缩聚制备了具有3种不同分子量的均苯型热塑性聚酰亚胺模塑粉, 并研究了其组成、 聚集态结构、 熔体黏度、 稳定性和热性能, 将模塑粉模压成型后进行机械性能测试. 结果表明, 引入柔性的二胺, 模塑粉的玻璃化转变温度(T_g)与传统的均苯型聚酰亚胺相比明显下降, 熔体黏度大幅度下降, 且具有良好的熔体黏度稳定性. 同时, 均苯四甲酸酐的存在保证了该模塑粉具有优异的热稳定性和优异的机械性能及较低的吸水率.     

新型超支化聚(芴-co-吡啶并[3,2-b]吡嗪)共聚物的合成与发光性能

合成了新型三溴代的含有吡啶并[3,2-b]吡嗪的化合物, 通过Suzuki缩聚反应合成了以吡啶并[3,2-b]吡嗪为核, 以9,9-二辛基芴为枝的超支化共聚物. 该共聚物在甲苯和四氢呋喃等有机溶剂中具有较好的溶解性能. 采用共聚物制备了结构为ITO/PEDOT/polymer/Ca/Al的发光器件, 其中基于共聚物PFPQ-2的器件在电流密度为3.8 mA/cm²时得到蓝光发射, 最大外量子效率为1.29%, 最大亮度为1173 cd/m², 色坐标为(0.16, 0.11).     

Phase-inversion gradient-porous films on the basis of polyamidoimides derived from phthalimidobenzenedicarbonyl dichloride and various diamines

Morphology of microporous films prepared from aromatic polyamidoimides under different molding conditions was studied by scanning, transmission, and atomic force microscopy with the specific attention given to the nanosize skin layer. The films were manufactured by the phase inversion molding of aromatic polyamidoimides which were synthesized by low-temperature polycondensation of phthalimidobenzenedicarbonyl dichloride with various diamines. Comparison of the parameters of films, including their wettability and X-ray photoelectron spectroscopy data, gave additional information on factors affecting the mechanism of formation of microporous membranes in the system polymer (polyamidoimide)-solvent (N-methylpyrrolidin-2-one)-non-solvent (water).     

聚合物主体中纳米CdTe的光致发光与电致发光性质

利用紫外和荧光光谱技术研究了共轭聚合物PPE4+分别在溶液和薄膜中与纳晶CdTe间的能量传递现象。通过静电层层组装技术制备了混杂有纳晶CdTe的PPE4+薄膜发光二极管,并测试了其电致发光性质。结果表明在溶液和薄膜中共轭聚合物PPE4+与纳晶CdTe间均能发生有效的能量转移,而共轭聚合物PPE4+在能量传递过程中起到分子天线的作用。     

A novel hierarchical crystalline structure of injection-molded bars of linear polymer: co-existence of bending and normal shish–kebab structure

The hierarchy structures and orientation behavior of high-density polyethylene (HDPE) molded by conventional injection molding (CIM) and gas-assisted injection molding (GAIM) were intensively examined by using scanning electronic microscopy (SEM) and 2D wide-angle X-ray diffraction (2D-WAXD). Results show that the spatial variation of crystals across the thickness of sample molded by CIM was characterized by a typical skin–core structure as a result of general shear-induced crystallization. Unusually, the crystalline morphologies of the parts prepared by GAIM, primarily due to the penetration of secondary high-compressed gas that was exerted on the polymer melt during gas injection, featured a richer and fascinating supermolecular structure. Besides, the oriented lamellar structure, general shish–kebab structure, and common spherulites existed in the skin, sub-skin, and gas channel region, respectively; a novel morphology of shish–kebab structure was seen in the sub-skin layer of the GAIM parts of HDPE. This special shish–kebab structure (recognized as “bending shish–kebab”) was neither parallel nor perpendicular to the flow direction but at an angle. Furthermore, there was a clear interface between the bending and the normal shish–kebab structures, which may be very significant for our understanding of the melt flow or polymer rheology under the coupling effect of multi-fluid flow and complex temperature profiles in the GAIM process. Based on experimental observations, a schematic illustration was proposed to interpret the formation mechanism of the bending shish–kebab structure during GAIM process.     

Study on mechanical properties of co-injection self-reinforced single polymer composites based on micro-morphology under different molding parameters

Self-reinforced single polymer composites (SRCs), which are fabricated by combining the same type of polymer with different properties into one body, have high specific strength, no interfacial heterogeneity, and ease of recycling. To better understand the relationship between the micro-morphology and mechanical properties of SRCs, the co-injection molding process was used in this study to process SRCs parts with different molding parameters and obtain the co-injection self-reinforced single polymer composites parts(CI-SRCs parts). Further, the micro-morphology of CI-SRCs parts were observed by polarizing microscope (PLM), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and wide Angle X-ray diffraction (WAXD). From the results, it was found that the tensile properties of CI-SRCs parts with different molding parameters were improved by up to 23.94% compared with the conventional parts. Through PLM observation, it is found that the section shape of CI-SRCs parts perpendicular to the flow direction shows a double ‘skin-core’ structure, and the area ratio of skin layer was higher than that of conventional parts, with a maximum increase of 68%. The low-temperature and low-speed environment were conducive to the formation of skin layer, and the tensile property of CI-SRCs parts were positively correlated with the area ratio of skin layer. SEM was carried out on the skin layer near the fusion position of the interface, and the highly oriented ‘shish-kebab’ structure was observed. The 1D-WAXD pattern analysis shows that the crystallinity of CI-SRCs parts were lower than that of conventional parts, with a maximum reduction of 19.32%. The crystallinity of CI-SRCs parts were positively correlated with melt temperature gradient, and its tensile properties were negatively correlated with the change of crystallinity. The 2D-WAXD pattern analysis shows that the molecular orientation of CI-SRCs parts were higher than conventional parts, with the maximum increase of 37.44%. Low temperature and low speed can improve the molecular orientation of CI-SRCs parts, and the change of molecular orientations were positively correlated with the tensile properties of CI-SRCs parts. By means of response surface method, the molecular orientation obtained was the decisive factor affecting the performance of CI-SRCs parts. Furthermore, by means of the least squares minimization program, the dimensionless equations among molding parameters, micro-morphologies and mechanical properties were established. The prediction of mechanical properties of CI-SRCs parts based on micro-morphologies were realized, providing theoretical support for the ‘adjustability’ of CI-SRCs parts properties.     

Duplication of photoinduced azo polymer surface-relief gratings through a soft lithographic approach

In this work, a soft lithographic approach has been developed to duplicate photoinduced surface-relief-gratings (SRGs) of azo polymer films to generate the surface pattern replicas composed of different materials on various substrates. For this purpose, thin films of an epoxy-based azo polymer (BP-AZ-CA) were prepared by spin-coating, and SRGs with different structures were inscribed by exposing the films to interference patterns of Ar(+) laser beams at modest intensity (150 mW/cm(2)). Using the azo polymer films as masters, stamps of poly(dimethylsiloxane) (PDMS) were prepared by replica molding. The PDMS stamps were then used to transfer the solutions of poly(3-hexylthiophene) (P3HT), multiwalled carbon nanotube (MWNT), and BP-AZ-CA to different substrates by contact printing. Through this process, surface pattern replicas made of the functional materials were obtained. The pattern formation and quality depended on the factors such as the solution concentration, contacting time in the printing process, and printing pressure. Under the proper conditions, the printed patterns showed the same grating periods as the masters and the same relief depths as the stamps (replicas of the masters). This approach, showing some attractive characteristics such as the easiness of master preparation and the versatility of soft fabrication processes, can be applied to the fabrications of optical functional surfaces, sensors, and photonic devices.     

Patterned deposition at moving contact lines

When a simple or complex liquid recedes from a smooth solid substrate it often leaves a homogeneous or structured deposit behind. In the case of a receding non-volatile pure liquid the deposit might be a liquid film or an arrangement of droplets depending on the receding speed of the meniscus and the wetting properties of the system. For complex liquids with volatile components as, e.g., polymer solutions and particle or surfactant suspensions, the deposit might be a homogeneous or structured layer of solute — with structures ranging from line patterns that can be orthogonal or parallel to the receding contact line via hexagonal or square arrangements of drops to complicated hierarchical structures. We review a number of recent experiments and modelling approaches with a particular focus on mesoscopic hydrodynamic long-wave models. The conclusion highlights open question and speculates about future developments.     

X-ray diffraction study of the structure of carboxymethylcellulose-cationic surfactant complexes.

We have investigated dilute aqueous solutions of an anionic polymer (carboxymethylcellulose) mixed with cationic surfactants of different chain lengths (dodecyl to octadecyl trimethylammonium bromides: DTAB, TTAB, CTAB and OTAB). The structures of the concentrated phases formed above the precipitation threshold were studied by X-ray diffraction. Different body-centred cubic structures with space groups Pm3n were observed in the presence of surfactant with a short aliphatic chain (DTAB), despite the fact that the polymer persistence length is comparable to the repeat distance of the structure (5 nm). For larger surfactant chain lengths (TTAB and CTAB), the structure of the precipitates can be either cubic (Pm3n) or 2D hexagonal depending on the initial surfactant and polymer concentrations. For still larger chain length (OTAB), the structure becomes lamellar. This structural evolution from micellar cubic towards 2D hexagonal and lamellar is attributed to the decrease of the local curvature of the surfactant aggregates, as observed for flexible synthetic polymers and short DNA fragments under similar conditions. Furthermore, the structure of the bulk complexes formed just below the precipitation threshold anticipates the structure seen in the precipitated phases.     

多层核-壳结构P(AM-co-MAA)/W/UF复合微球制备研究

以反相悬浮聚合技术合成的丙烯酰胺(acrylamide,AM)和甲基丙烯酸(methacrylic acid,MAA)共聚高分子微凝胶P(AM-co-MAA)为模板,通过离心沉积法将微米级钨粉沉积于高分子微凝胶表面,得到具有核-壳结构的P(AM-co-MAA)/W复合微球材料;再以P(AM-co-MAA)/W复合微球为模板,通过控制甲醛和尿素的缩聚反应在模板与油/水相界面进行,制备得到了具有多层核-壳结构的高分子/钨/脲醛树脂[P(AM-co-MAA)/W/Urea-formaldehyde resin]复合微球材料.利用扫描电子显微镜(SEM)、红外(FT-IR)、X射线衍射(XRD)和热分析(TGA)等手段对复合微球进行了表征.实验结果表明,外壳层脲醛树脂的包覆量、复合微球的表面形貌可通过改变甲醛和尿素溶液的浓度、甲醛和尿素的物质的量之比等因素进行控制.复合微球的导电性测试结果表明,P(AM-co-MAA)/W复合微球表面壳层脲醛树脂包覆前后,其电导率由1.9×10-3降低为0.9×10-8S·m-1.该研究获得的三层核-壳复合微球材料其外层脲醛树脂的包覆较为完整、致密,其导电性接近于绝缘材料,为含钨复合微球作为电子元件的抗辐射涂层材料打下了基础.     

Water soluble amino grafted silicon nanoparticles and their use in polymer solar cells

Stable aqueous amino-grafted silicon nanoparticles(SiNPs-NH2) were prepared via one-pot solution method. By grafting amino groups on the particle surface, the dispersion of SiNPs in water became very stable and clear aqueous solutions could be obtained. By incorporating SiNPs-NH2 into the hole transport layer of poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid(PEDOT:PSS), the performance of polymer solar cells composed of poly[2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene](MEH-PPV):[6,6]-phenyl-C61-butyric acid methyl ester(PCBM) as active layer can be improved. SiNPs-NH2 are dispersed uniformly in the PEDOT:PSS solution and help form morphologies with small-sized domains in the PEDOT:PSS film. SiNPs-NH2 serve as screens between conducting polymer PEDOT and ionomer PSS to improve the phase separation and charge transport of the hole transport layer. As a result, the sheet resistance of PEDOT:PSS thin films is decreased from(93 ± 5) × 105 to(13 ± 3) × 105 ?/□. The power conversion efficiency(PCE) of polymer solar cells was thus improved by 9.8% for devices fabricated with PEDOT:PSS containing 1 wt% of SiNPs-NH2, compared with the devices fabricated by original PEDOT:PSS.