OCVD polymerization of PEDOT: effect of pre‐treatment steps on PEDOT‐coated conductive fibers and a morphological study of PEDOT distribution on textile yarns

The functionalization of textile fibers with intrinsically conductive polymers has become a prominent research area throughout the world. A number of coating techniques have already been utilized and optimized to get the uniform layers of conductive polymers on the surface of different substrates. In our previous study, we produced poly(3,4‐ethylenedioxythiophene) (PEDOT)‐coated conductive fibers by employing oxidative chemical vapor deposition (oCVD) technique. This paper describes the effects of pre‐treatment steps, such as surface treatment of textile fibers with organic solvents, drying of oxidant‐enriched fibers at variable temperatures and time, and oxidant type on the electrical, mechanical, and thermal properties of PEDOT‐coated conductive fibers. Two well‐known oxidants, ferric(III)chloride and ferric(III)p‐toluenesulfonate (FepTS), were studied, and then their results were compared. In order to verify the PEDOT‐coated layer and, to some extent, its impregnation inside the viscose yarns, a morphological study was carried out by using the attenuated total reflectance Fourier transform infrared spectroscopic imaging technique and computed tomography scanning across the obtained conductive fibers. Differential scanning calorimetric and thermogravimetric analysis were utilized to investigate the thermal properties and the contents of PEDOT in PEDOT‐coated fibers. The mechanical properties of conductive fibers were evaluated by tensile strength testing of produced fibers. Effects of all of these pre‐treatment steps on electrical properties were analyzed with Kiethly picoammeter. This study cannot only be exploited to improve the properties of conductive fibers but also to optimize the oCVD process for the production of conductive textile fibers by coating with different conjugated polymers. Copyright © 2012 John Wiley & Sons, Ltd.     

Improvement of sensitivity in the determination of organochlorine pesticides using a PSS injector with GC-ECD

This paper describes the optimisation of a PSS injector in a gas chromatograph with a programmed pneumatic control (PPC) for the determination of 21 organochlorine pesticides. The injection of high volumes of sample (20 l) improves the detection limits and allows a reduction in the amount of sample processed. The injection conditions were selected by a Plackett–Burman design followed by a central composite design. The LODs obtained in the optimum conditions were compared with those obtained with splitless/ECD. Finally, the method was successfully applied to the analysis of a leachate and vegetable samples.     

Screen-printed poly(3,4-ethylenedioxythiophene) (PEDOT): A new electrochemical mediator for acetylcholinesterase-based biosensors

This work describes the use of a PEDOT:PSS-based conductive polymer for designing AChE-based biosensors. The transducers were obtained directly by screen-printing a PEDOT:PSS suspension on the surface of thick film carbon electrodes. The obtained working electrodes showed a high conductivity when compared with electrodes modified with conventional mediators like cobalt phthalocyanine or tetracyanoquinodimethane. The PEDOT:PSS polymer was shown to be suitable for thiocholine oxidation, allowing the measurement of AChE activity at 100 mV vs Ag/AgCl. The high conductivity of PEDOT:PSS allowed the accurate detection of the organophosphate insecticide chlorpyrifos-oxon at concentrations as low as 4 × 10⁻⁹ M, corresponding to an inhibition ratio of 5%.     

Novel flexible chemical gas sensor based on poly(3,4-ethylenedioxythiophene) nanotube membrane

Poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT NTs) flexible membrane was successfully fabricated by vapor deposition polymerization (VDP) mediated electrospinning for ammonia gas detection. PVA nanofibers (NFs) were electrospun as a core part and polyvinyl alcohol (PVA)/PEDOT coaxial nanocables (NCs) were prepared by VDP method via EDOT monomer adsorption onto the electrospun PVA NFs as templates. To obtain the PEDOT NTs membrane, the PVA NFs were removed from PVA/PEDOT coaxial NCs with distilled water. PVA/PEDOT coaxial NCs and PEDOT NTs had the conductivities of 71 and 61 S cm⁻¹ and were applied as a transducer for ammonia gas detection in the range of 1-100 parts per million (ppm) of NH₃ gas. They exhibited the minimum detectable level of ca. 5 parts per million (ppm) and fast response time (less than 1 s) towards ammonia gas. In a recovery time, the PEDOT NTs membrane sensor was ca. 30 s and shorter compared to that of the membrane sensor based on the PVA/PEDOT NCs (ca. 50 s). In addition, sensor performance of PEDOT NTs membrane was also undertaken as a function of membrane thickness. Thick membrane sensor (30 μm) had the enhanced sensitivity and the sensitivity on the membrane thickness was in the order of 30 μm > 20 μm > 10 μm at 60 ppm of NH₃ gas.     

Polypropylene-polysilsesquioxane blends

This paper deals with the preparation of PP/polysilsesquioxane blends and their study to investigate silsesquioxane dispersion, mechanical properties, thermal stability and combustion properties by means of a number of techniques, such as SEM, XRD, Rheology, TGA, DSC, Cone Calorimeter tests and LOI.Polysilsesquioxane with different organic groups (methyl, vinyl or phenyl) were used; both dispersion and final properties were found to be dependent on the silsesquioxane organic fraction type.The PP/polysilsesquioxane blends showed an increased thermoxidative stability and combustion resistance, in terms of lower rate of heat release.Higher mechanical performances were also achieved with PP/vinyl polysilsesquioxane, with higher elastic modulus as well as higher elongation at break.     

Ti_3C_2T_x/PEDOT:PSS hybrid materials for room-temperature methanol sensor

It is essential to develop a methanol gas sensor with high selectivity and low working temperature for human health and environmental monitoring.In this work,a blend of PEDOT:PSS and Ti_3C_2T_x with the mass ratio of 4:1 is used to fabricate a methanol gas sensor.It possesses a high response ratio of the largest response and the second largest response(5.54) and an enhanced response compared to pure PEDOT:PSS and pure Ti_3C_2T_x tested at room temperature.These findings may pave the way towards design of the MXenes based high-performance gas-sensing materials in the future.     

伪火花放电开关电压跌落过程实验研究

 设计了典型参数下的伪火花放电开关，进行了空气介质下的电压特性实验，给出了伪火花开关放电电压与气压变化的关系曲线；测量了产生伪火花放电的气压范围（1~29Pa）和单间隙伪火花放电开关耐受电压的最大值(40kV)，测得了伪火花放电与辉光放电的转折点气压(29Pa)，并对实验结果进行了理论分析。研究了伪火花放电开关电压跌落时间与放电电压的关系，首次将开关电压跌落过程分为暂态阶段和稳态阶段，讨论了放电电路参数，气体压力，开关结构和放电电压对电压跌落时间的影响。实验表明，在气压和开关结构不变的条件下，暂态过程时间由放电电压决定，电压越高，则所需时间就越短；稳态过程时间由放电电路参数决定，不受放电电压影响。     

稀释溶剂对PEDOT：PSS薄膜和有机太阳能电池性能的影响

采用喷涂技术制备聚3,4-乙撑二氧噻吩：聚苯乙烯磺酸盐（PEDOT：PSS）有机层薄膜,系统研究了乙醇、去离子水、甲醇、异丙醇和乙二醇等稀释溶剂对PEDOT：PSS薄膜形貌、透过率及导电性能的影响。将PEDOT：PSS薄膜应用于有机太阳能电池器件的制备,研究了不同溶剂对器件性能的影响。实验结果表明：采用乙醇稀释PEDOT：PSS溶液,能有效抑制PEDOT：PSS颗粒团聚,降低薄膜粗糙度,提高薄膜的透过率和导电性。以其制备的太阳能电池器件的能量转换效率明显高于其他溶剂稀释,转换效率为2.66%。     

Thermoelectric behavior of organic thin film nanocomposites

Organic thin film nanocomposites, prepared by liquid‐phase exfoliation, were investigated for their superior electrical properties and thermoelectric behavior. Single‐walled carbon nanotubes (SWNT) were stabilized by intrinsically conductive poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in an aqueous solution. The electrical conductivity (σ) was found to increase linearly as 20 to 95 wt % SWNT. At 95 wt % SWNT, these thin films exhibit metallic electrical conductivity (～4.0 × 10⁵ S m^?1) that is among the highest values ever reported for a free‐standing, fully organic material. The thermopower (S) remains relatively unaltered as the electrical conductivity increases, leading to a maximum power factor (S²σ) of 140 μW m^?1 K^?2. This power factor is within an order of magnitude of bismuth telluride, so it is believed that these flexible films could be used for some unique thermoelectric applications requiring mechanical flexibility and printability. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Synthesis and characterization of all‐conjugated copolymers of 3‐hexyl‐thiophene and EDOT by grignard metathesis polymerization

Random regioregular copolymers of 3‐hexylthiophene and 3,4‐ethylenedioxythiophene were synthesized by grignard metathesis polymerization. Soluble copolymers were obtained with a high degree of regioregularity and with a monomer ratio close to the feed ratio. A comparison between the optical properties and the thin film morphologies of these copolymers and poly(3‐hexylthiophene) is also presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011