Interfacial synthesis of platinum loaded polyaniline nanowires in poly(styrene sulfonic acid)

Polyaniline-poly(styrene sulfonic acid)-platinum (PANI-PSS-Pt) composite is prepared through an interfacial polymerization route. The composite is obtained by incorporating Pt nanoparticles into conductive PANI matrix by the reduction of Pt⁴⁺ ions to Pt nanoparticles during the oxidative polymerization of aniline in PSS as medium. The interfacial synthesis offers the microenvironment for the growth of PANI nanostructures with simultaneous incorporation of Pt nanoparticles to result PANI-PSS-Pt nanocomposite. PANI-PSS-Pt nanocomposite is characterized by UV-Vis absorption spectroscopy, FTIR spectroscopy, scanning microelectronic microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).     

碱性甲醇燃料电池用季铵化PPEK膜的研究

聚合物碱性甲醇燃料电池是一种正在兴起的移动电源,氢氧根离子交换膜是碱性甲醇燃料电池的关键材料题之一.从聚二氮杂萘酮醚酮(PPEK)出发,依次采用氯甲基化、溶液法流延成型、三甲胺季铵化和KOH溶液处理等方法,制备了季铵碱型的聚二氮杂萘酮醚酮(QPPEK-OH)电解质膜,测定了膜的电导率和甲醇渗透性.研究发现,每个重复链节中平均含有1.3个季铵碱离子的聚二氮杂萘酮醚酮膜,导电率和甲醇的渗透系数分别为1.14×10-2S/cm和6.57×10-7cm2/s.     

Surface modification of poly(3,4-ethylene dioxthiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films by atmospheric-pressure argon plasma for organic thin-film solar cells

Highly-conductive poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films obtained by the addition of dimethylsulfoxide (DMSO) and the argon plasma exposure were used as a transparent conductive anode (TCA) for copper-phthalocyanine (CuPc)/C60 organic thin-film solar cells (OSCs). The CuPc/C60 OSCs on as-grown DMSO added PEDOT:PSS layer showed a power efficiency of 0.6%, whereas it was improved markedly to 1.34% after the atmospheric-pressure argon plasma exposure, which was comparable to that formed on indium-tin-oxide layer. Effects of the DMSO addition and the argon plasma exposure in the spin-coated PEDOT:PSS films is demonstrated in terms of the in-depth characterization of optical and electrical properties.     

Dihydrogenimidazole modified silica-sulfonated poly(ether ether ketone) hybrid materials as electrolyte membranes for direct ethanol fuel cells

The present study reports on dihydrogenimidazole modified inorganic-organic mixed matrix membranes for possible application as a proton exchange membrane in direct ethanol fuel cells. The polymeric phase consisted mainly of sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree of 55%. The inorganic phase was built up from hydrophilic fumed silica particles interconnected with partially hydrolyzed and condensed tetraethoxysilane with a total inorganic loading of 27.3%. This inorganic phase was further modified with N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (DHIM), which consists of an hydrolyzable inorganic part and a functional organic group. The influence of the modifier on the mixed matrix system was studied by means of various modifier concentrations in various aqueous-ethanolic systems (water, 2 M and 4 M ethanol). Modifier concentration and ethanol concentration of the ethanol-water mixture exhibited significant but opposite effects on the liquid uptake of the mixed matrix membranes. The proton conductivity as well as the proton diffusion coefficient as a function of modifier content showed a linear decrease. The proton conductivity as a function of temperature showed Arrhenius behavior and the activation energy of the mixed matrix membranes was 43.9 ± 2.6 kJ mol⁻¹. High selectivity of proton diffusion coefficient to ethanol permeability coefficient was obtained with high modifier concentrations. At low modifier concentrations, this selectivity was dominated by ethanol permeation and at high modifier concentrations by proton diffusion. The main electrolyte properties can be optimized by setting the DHIM content in mixed matrix membrane. With this approach, tailor-made membranes can be prepared for possible application in direct ethanol fuel cells.     

Real-time ellipsometric characterization of the initial growth stage of poly(3,4-ethylene dioxythiophene): poly(styrene sulfonic acid) films by electrospray deposition

Kinetic spectroscopic ellipsometry have been used to study the initial growth stage of poly(3,4-polyethylene dioxythiophene):poly(styrenesulfonic acid)(PEDOT:PSS) films by the electrospray deposition (ESD) method. The real-time spectra analysis revealed that the surface overlayer decreased in thickness once the first bulk layer monolayer was formed, indicating a smoothening effect as the nucleation-related microstructure coalesced into the bulk layer. Once the coalescence was completed and the nucleation-induced surface roughness layer was stabilized, the underlying bulk layer increased linearly with time. These results originate from the degrees of the evaporation of solvent material during the transferring the precursors to the surface and/or of the diffusion of deposition precursors after sticking at the growing surface.     

Proton-conducting membrane preparation based on SiO2-riveted phosphotungstic acid and poly (2,5-benzimidazole) via direct casting method and its durability

SiO₂-riveted phosphotungstic acid (T–PWA–SiO₂) was synthesized using the sol–gel method and thermally treated in a microwave synthesizer. The dissolving-detaching experiment shows that PWA in T–PWA–SiO₂ exhibits better fastness than in the sample without thermal treatment (PWA–SiO₂). The T–PWA–SiO₂ samples were then combined with poly(2,5-benzimidazole) (ABPBI) to prepare ABPBI/(T–PWA–SiO₂) composite membranes using the polyphosphoric acid direct-casting method. These composite membranes were characterized through X-ray diffraction and infrared spectroscopy. Then, the T–PWA–SiO₂ particles were combined with ABPBI through hydrogen bonding between PWA and C=N in ABPBI. Membrane morphologies were investigated using scanning electron microscopy. Results of the thermogravimetric analysis indicate thermal stability of the composite membranes below 200 °C. The proton conductivity and durability between ABPBI/(T–PWA–SiO₂) and ABPBI/(PWA–SiO₂) composite membranes were also compared. The conductivity and life of the composite membranes were enhanced using T–PWA–SiO₂. The conductivity of the ABPBI/(T–PWA–SiO₂) (46 wt%) composite membrane was approximately 0.055 S/cm at 180 °C under 100% relative humidity.     

Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview

Polymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity. The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on modified-Nafion membranes. Energy security refers to various security measures that a given nation, or the global community as a whole, must carryout to maintain an adequate energy supply     

界面聚合法合成苯胺与邻甲氧基苯胺的樟脑磺酸掺杂共聚物及其表征

采用界面聚合法在樟脑磺酸存在的状态下合成了聚苯胺、聚邻甲氧基苯胺以及苯胺与邻甲氧基苯胺的共聚物.利用红外光谱,紫外可见吸收光谱,电子扫描微电镜,X-射线粉末衍射,循环伏安,电导率测试等手段对聚合物进行了表征,初步探讨了单体配比对共聚物形貌、结构及性能的影响.结果表明,界面聚合法合成的上述各聚合物均呈现微米级颗粒状分布,颗粒直径大多在100nm以内;共聚后聚合物的结晶性能下降;循环伏安及电导率测试结果表明,随着聚合物主链中邻甲氧基苯胺结构单元的增加,聚合物的电化学活性及电导率呈下降趋势.     

Fabrication of high yield and highly crystalline poly(2,5-dimethoxyanline) nanoplates using various organic sulfonic acids as the dopant agents and soft-templates

This paper demonstrates a simple and effective approach to fabricate highly crystalline poly(2,5-dimethoxyaniline) (PDMA) nanoplates using various organic sulfonic acids including Dodecyl benzenesulfonic acid (DBSA), Camphorsulfonic acid (CSA) and p-Toluenesulfonic Acid (p-TSA) as the dopant agents. The structures and morphologies of PDMA nanoplates were characterized using Fourier transform infrared spectrometer, Raman spectrometer, X-ray diffraction, Atom force microscope and Electron microscope. The results show that the PDMA nanoplates possess high crystallinity and layered nanoplate aggregation structure. The estimated degree of crystallinity is higher than 95 %. With different organic sulfonic acids used, the aggregation structures of PDMA nanoplates vary from triclinic hexahedron to cuboid and rod shape. Through adjusting the dopant agent/monomer molar ratio, the yield of PDMA nanoplates can be as high as 53 %.     

Effects of thermal annealing as polymer processing step on poly(lactic acid)

Thermal annealing as an additional polymer processing step or post-treatment processing step enables the structural changes of amorphous parts into crystalline parts. This paper investigates the feasibility of thermal annealing at 100°C up to 90?min used as an additional processing step to modify the crystalline structure and the thermo-mechanical stability of poly(lactic acid) (PLA). Moreover, the crystallization ability of PLA has been amended by the addition of 3?wt% of wood flour and kaolin. The values of the degree of crystallinity and lamellar thickness determined by wide-angle-X-ray scattering showed that the thermal annealing of PLA samples modified with nucleating agents was an efficient processing step to increase the final crystallinity of PLA. Moreover, altered crystalline structure helped to improve the thermomechanical stability of PLA.     

Expression of basal lamina components by Schwann cells cultured on poly(lactic acid) (PLLA) and poly(caprolactone) (PCL) membranes

The present in vitro study investigated the expression of basal lamina components by Schwann cells (SCs) cultivated on PCL and PLLA membranes prepared by solvent evaporation. Cultures of SCs were obtained from sciatic nerves from neonatal Sprague Dawley rats and seeded on 24 well culture plates containing the polymer membranes. The purity of the cultures was evaluated with a Schwann cell marker antibody (anti-S-100). After one week, the cultures were fixed and processed for immunocytochemistry by using antibodies against type IV collagen, laminin I and II. Positive labeling against the studied molecules was observed, indicating that such biomaterials positively stimulate Schwann cell adhesion and proliferation. Overall, the present results provide evidence that membrane-derived biodegradable polymers, particularly those derived from PLLA, are able to provide adequate substrate and stimulate SCs to produce ECM molecules, what may have in turn positive effects in vivo, influencing the peripheral nerve regeneration process.     

Solid polymer electrolytes based on poly(vinylchloride)–lithium sulfate

Ionic conductivity studies in the temperature range 304–373 K for PVC---Li₂SO₄---dibutylphthalate polymer electrolyte systems are reported and discussed. Poly(vinylchloride) (PVC) has an electrical conductivity 10⁻⁸ S cm⁻¹. The prepared films were studies by X-ray diffraction, Fourier transformation infrared, scanning electron microscopy and thermal analysis. The temperature dependence of the conductivity of the polymer films obeys the Vogel–Tammann–Fulcher relation.     

In vivo interaction of cells on poly L-(lactic acid) membranes containing plasticizer

The development of biodegradable materials has lead to renewed interest in the study of their interactions with the host organism in order to make the resulting products appropriate for use as temporary materials in protheses. Poly L-(lactic acid)(PLLA)-based biodegradable devices have been used for several purposes. The physical properties of these materials can be modified by the addition of a plasticizer, such as the triethylcitrate, to provide flexibility and porosity to the implants and enhance control of the polymer degradation time. In this work we examined the biological properties of a PLLA porous membrane containing 7% triethylcitrate, by assessing the process of degradation and the interaction with dermal tissue. Samples of skin obtained from female Wistar rats 2–180 days after implantation with PLLA-based membrane were processed for light microscopy and scanning electron microscopy. The membranes became surrounded by a delicate network of connective tissue which gradually invaded the membrane structure. Polymer degradation began with the appearance of radial fractures in the globular units of the biodegradable membrane, especially by 90 and 180 days after implantation.     

3-Methyltrimethylammonium poly(2,6-dimethyl-1,4-phenylene oxide) based anion exchange membrane for alkaline polymer electrolyte fuel cells

Hydroxyl ion (OH^?) conducting anion exchange membranes based on modified poly (phenylene oxide) are fabricated for their application in alkaline polymer electrolyte fuel cells (APEFCs). In the present study, chloromethylation of poly(phenylene oxide) (PPO) is performed by aryl substitution rather than benzyl substitution and homogeneously quaternized to form an anion exchange membrane (AEM). ¹H NMR and FT-IR studies reveal successful incorporation of the above groups in the polymer backbone. The membrane is characterized for its ion exchange capacity and water uptake. The membrane formed by these processes show good ionic conductivity and when used in fuel cell exhibited an enhanced performance in comparison with the state-of-the-art commercial AHA membrane. A peak power density of 111 mW/cm² at a load current density of 250 mA/cm² is obtained for PPO based membrane in APEFCs at 30 °C.     

Synthesis and characterization of poly(2,5-dimethoxyaniline) and poly(aniline-Co-2,5-dimethoxyaniline): The processable conducting polymers

Poly(2,5-dimethoxyaniline) (PDMOA) and its copolymers with aniline (PADMOA), which exhibit remarkably improved solubility in common organic solvents, were obtained by chemical polymerization, and characterized by a host of physical techniques. The lowering of the quinoid absorption in the IR spectra and the upshifting of the N_1s envelope in the XPS spectra indicate residual doping in the XPS polymers and thermal characteristic of the polymers provide evidence for hydrogen bonding, which appear to enhance the thermal stability of the homopolymer. These polymers are highly planar and conjugated, with well-developed polaronic features, shown by the XRD, ESR and UV-spectral data. The conductivity, however, is not high and apparently may be due to localization of polaronic charges at the hydrogen-bonding sites and the increased proportion of the insulating methoxy component in the polymer matrix.