Low-temperature NO_2 sensors based on polythiophene/WO_3 organic-inorganic hybrids

Polythiophene （PTP） was prepared by a chemical oxidative polymerization and nanosized WO3 was prepared by a colloidal chemical method. The organic-inorganic PTP/WO3 hybrids with different mass fractions of PTP were obtained by a simple mechanically mixing the prepared PTP and WO3. The as-prepared PTP/WO3 hybrids have a higher thermal stability than the pure PTP. The gas sensing measurements demonstrate that the PTP/WO3 hybrid sensors exhibit higher response for detecting NO2 at low temperature than the pure PTP and WO3 sensor. The sensing mechanism is suggested to be related to the existence of p-n heterojunctions in the PTP/WO3 hybrids. The response of the PTP/WO3 hybrids is markedly influenced by the PTP mass fraction. The 20% PTP/WO3 hybrid shows high response and good selectivity to NO2 at low temperature （〈90℃）. Therefore, the PTP/WO3 hybrids can be expected to be potentially used as gas sensor material for detecting NO2 at low temperature.

Electrochemical Synthesis of Polythiophene in an Ionic Liquid

Polythiophene (PTh) was prepared by the direct electrochemical synthesis in an ionic liquid ([BMIM]PF6) containing 0.1 mol/L thiophene by cyclic voltammetry, constant potential and constant current techniques. It is found that smooth and bluegreen PTh films can be obtained at a potential of ca. +1.75 V ( vs. Ag/AgCl ) or a current of ca. 1.5 mA cm-2 in the ionic liquid.

DEFORMATION MEASUREMENT OF CON-DUCTING POLYTHIOPHENE THIN FILMS BY AN ELECTRONIC SPECKLE PATTERN INTERFEROMETRIC METHOD

The deformation measurement of electrosynthesized polythiophene(Pth) thin films is difficult because of the small thickness and highflexibility of the specimen. An electronic speckle patterninterferom- etry (ESPI) method is used to measure the deformation ofPth films of thicknesses in the range of 4-65 μm . Theirstress-strain curves are obtained. It is found that the mechanicalproperties of Pth films are sensitive to the specimen thickness. Thetensile strength increases with decreasing thickness of thin filmfrom 10 μm. The influence of the electrochemical synthesisconditions on the mechanical properties of Pth films is also dis-Cussed.

Preparation of polythiophene/WO_3 organic-inorganic hybrids and their gas sensing properties for NO_2 detection at low temperature

Polythiophene/WO3（PTP/WO3）organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and thermo-gravimetric analysis（TGA）.The Polythiophene/ WO3 hybrids have higher thermal stability than pure polythiophene,which is beneficial to potential application as chemical sensors.Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for de- tecting NO2 of ppm level at low temperature.Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2.The 10 wt%PTP/WO3 hybrid showed the highest response at low operating temperature of 70-C.It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.

LOW POTENTIAL ELECTROPOLYMERIZATION OF ANISOTROPIC CONDUCTIVE POLYTHIOPHENE FILMS AND FABRICATION OF ELECTRICAL DEVICES

The Complexation of thiophene with a Lewis acid with moderate acidity as a solvent, such as BF3-ethyl ether (BFEE) remarkedly lowered the electrochemical polymerization potential. The positively charged metal surface of electrode in the process of electrochemical deposition enhanced the coordination interaction between pi-electrons of thiophene unit and the metal, which makes thiophene rings lie parallel to the surface of electrode, resulting in a highly ordered polymeric structure. Because of the large intra-chain transfer integrals, the transport of charge is believed to be principally along the conjugated chains, which is much greater than the inter-chain hopping. The specific electrical resistance across the polythiophene film thickness is more than 10(4) times than that along the surface plane of the film. In this paper we review the recent development of polymerization technique by low potential electrochemical method performed in our lab and several electrical devices in which the compact polythiophene films, such as anionic and cationic sieves, and laminate film junction of undoped polythiophene derivatives were used.

hsTnI、PTH及BNP水平与CKD5期患者高血压分级的相关性研究

目的:探讨血清高敏肌钙蛋白I(hsTnI)、甲状旁腺激素(PTH)及血浆钠尿肽(BNP)水平与慢性肾脏病(CKD)5期患者高血压分级的相关性及临床意义。方法:选取85例CKD5期并伴有不同程度高血压的患者作为研究组,其中高血压I级(甲组)17例,IⅡ级(乙组)26例,Ⅲ级(丙组)42例,30例同期入院体检的健康对象作为对照组。比较3组患者hsTnI、PTH及BNP水平与对照组的差异,并分析其与高血压分级的相关性。结果:甲、乙、丙组患者hsTnl、PTH及BNP水平均明显高于对照组(P<0.05);经Spearman相关性分析,hsTnl、PTH及BNP水平与高血压分级均为强正相关(P<0.001)。结论:血清hsTnI、PTH及血浆BNP水平与CKD5期患者高血压分级相关性强,对于CKD5期合并高血压患者的临床病情评估具有重要作用。

术后血清MMIF、IL-6及PTH水平与甲状腺乳头状癌术后甲状旁腺功能减退的相关性

目的分析术后血清巨噬细胞移动抑制因子(MMIF)、白介素-6(IL-6)及甲状旁腺激素(PTH)水平与甲状腺乳头状癌术后甲状旁腺功能减退的相关性。方法选取2020年6月至2022年4月于北京市平谷区医院确诊为甲状腺乳头状癌并采用甲状腺全切以及颈中央区淋巴结清扫手术患者134例为研究对象。统计患者术后甲状旁腺功能减退发生情况;分析影响患者甲状旁腺功能减退的单因素,并采用多元Logistic回归分析影响甲状旁腺功能减退的危险因素,采用Pearson系数分析术后血清MMIF、IL-6、PTH与甲状旁腺功能减退的相关性。结果134例患者术后甲状旁腺功能正常者112例(83.58%)、甲状旁腺功能减退者22例(16.42%);两组年龄、性别、肿瘤直径等指标比较,差异无统计学意义(P>0.05);两组肿瘤位置、中央区淋巴结清扫位置及数量、合并桥本甲状腺炎以及术后血清MMIF、IL-6、PTH水平比较,差异有统计学意义(P<0.05);多元Logistic回归分析显示:肿瘤位于后背膜、合并患有桥本甲状腺炎以及术后血清MMIF≥2 ng/mL、IL-6>10.0 pg/L、PTH≥15 pg/mL是影响甲状旁腺功能减退的危险因素(P<0.05);Pearson相关性分析可知:术后血清MMIF、IL-6、PTH水平与甲状旁腺功能减退呈正相关(P<0.05)。结论临床可通过检测术后血清MMIF水平、IL-6、PTH水平用以预测甲状腺乳头状癌术后甲状旁腺功能是否出现减退,为治疗提供可靠的依据。

In-situ Microscopic FT-IR Spectroelectrochemical Investigation of Polythiophene Film Modified Electrode

A polythiophene film was electrochemically deposited on a Pt micro plate electrode and investigated by cyclic voltammetry and in situ reflection microscopic FTIR spectroscopy. The FTIR analysis showed that the electropolymerization of thiophene on the Pt surface was affected by the surface adsorption processes of thiophene molecules. Two adsorption modes were identified. Two structure models of the polythiophene chain were observed simultaneously. It was proposed that the good conductibility of the polythiophene film was originated from a co vibratory equilibrium of the link part of model Ⅰ and model Ⅱ.

STRUCTURAL ANALYSIS AND ENVIRONMENTAL STABILITY OF POLYFLUORINATED GROUP SUBSTITUTED POLYTHIOPHENES

Electrochemical polymerization of 3-fluoroalkoxy and 3-fluoroether thiophenes gives polymers with relatively high molecular weights and good processibility. Investigation of these polymers by means of GPC indicates that an increase in the number of fluorine atoms in the fluorinated group results in a decrease in degree of polymerization of the polymers in the same polythiophene series. As shown by NMR and FTIR, the polyfluorinated group substituted polythiophenes have regular 2, 5-coupling in their main chains. The SEM micrographs of the polymer films exhibit that polymer (1)-poly [3-2, 2, 3, 3-tetrafluoro-propoxy) thiophene] possesses more regular structure than the other polymers do. Substitution of polythiophenes by fluorinated groups leads to the polymers with high electric, electrochemical and thermal stability.

Synthesis and Characterization of Polythiophenes Bearing Diphenyl Groups in the Conjugated Chain

4,4＇-dibromo-2-nitro-biphenyl and 4,4＇-dibromo-2,3＇-dinitro-biphenyl have been synthesized via nitration reaction with 4,4＇-dibromobiphenyl as the raw material. Three novel thiophene derivatives, 4, 4＇-di（4-hexyl-thiophen-2-yl）biphenyl, 4,4＇-di（4-hexyl-thiophen-2-yl）-2- nitro-biphenyl and 4,4＇-di（4- hexyl-thiophen-2-yl）-2,3＇-dinitrobiphenyl were synthesized through Stille coupling reaction, followed by polymerization in the presence of FeC13, respectively. UV-vis absorption spectra, fluorescence spectra, photoluminescence spectra and electrochemical properties of the polymers were investigated. And the band-gap （Eg）, HOMO orbital energy （EHCMO）, and LUMO orbital energy （EUJMO） of the polymers were calculated. Among the polymers, polymer PBTN and PBTD show lower band-gap （2.67 and 2.63 eV）, lower HOMO energy level （-5.38 and -5.4 eV） and broader wavelength （432 and 438 nm） than that of polymer PBTB （2.69 eV, -5.36 eV and 424 nm） with incorporation of one nitro group or two nitro groups in the main chain, respectively.

Charge and spin-dependent thermal efficiency of polythiophene molecular junction in presence of dephasing

The charge and spin-dependent thermoelectric properties of different lengths of polythiophene in a molecular junction are investigated using the B ¨uttiker probe method within Green function formalism in linear response regime. The coupling of the molecular chain to three-dimensional ferromagnetic electrodes is described by a tight-binding model for both parallel and antiparallel spin configurations. The decrease of height of transmission probability peaks and thermoelectric coefficients are observed in the presence of the B ¨uttiker probes. The reduction is more intensive in the strong dephased chains.Results show that the spin magnetothermopower is bigger than the charge magnetothermopower due to the larger difference between the spin thermopowers with respect to the charge ones. In addition, we observed that the kind of carriers participating in the thermoelectric transport depends on the number of the thiophene rings.

Polythiophene encapsulated inside(13, 0) CNT: A nano-hybrid system

We present a first-principles calculation on the electronic and optical properties of a hybrid nanotube system consisting of a （13, 0） single-walled carbon nanotube encapsulated by polythiophene. This hybrid-system represents a complete new type of matter and is known as the peapod system. We analyze bow the polythiophene changes the electronic and optical properties of the nanotube. In particular, we examine new features in the dielectric function due to the transitions between the states of the polymer and the nanotube. The electronic structure of the combined system appears to be a simple superposition of the individual constituents. The density functional theory calculations demonstrate van der Waals interaction as the bonding mechanism between the tube and the encapsulated molecule.

ELECTRONIC EFFECTS OF POLYFLUORINATED SUBSTITUENTS ON THE POLYMERIZATION AND THE PROPERTIES OF POLYTHIOPHENES

Three series of polythiophenes containing fluoroalkoxy and fluoroether substituents were prepared by electrochemical polymerization. The effect of substituents with fluoroalkoxy or ether functional groups on the electrochemical polymerization of thiophene monomers and properties of the obtained polymers were analyzed. The introduction of a fluoroether functional group at the 3-position of the thiophene ring leads to an increase of the oxidation potential of the monomer and to a decrease of the conductivity of the resulting polymers, even with the use of a CH2 group as spacer. Conversely, the presence of an oxygen atom directly at the 3-position of the thiophene ring, which offsets the negative withdrawing effect of fluoroalkyl groups, facilitates the synthesis of highly conducting polythiophenes.

Development of Conducting Polythiophene

Polythiophene and its derivatives are getting more andmore attention as a new kind of conducting polymers.Their conductivity,application,possible processingmethods and development are discussed in this article.

Dynamical study on charge injection and transport in a metal/polythiophene/metal structure

The dynamical process of charge injection from metal electrode to a nondegenerate polymer in a metal/polythiophene （PT）/metal structure has been investigated by using a nonadiabatic dynamic approach. It is found that the injected charges form wave packets due to the strong electron-lattice interaction in PT. We demonstrate that the dynamical formation of the wave packet sensitively depends on the strength of applied voltage, the electric field, and the contact between PT and electrode. At a strength of the electric field more than 3.0 × 10^4 V/cm, the carriers can be ejected from the PT into the right electrode. At an electric field more than 3.0 × 10^5 V/cm, the wave packet cannot form while it moves rapidly to the right PT/metal interface. It is shown that the ejected quantity of charge is noninteger.

Synthesis of Soluble Polythiophene Partially Containing 3,4-Ethylenedioxythiophene and 3-Hexylthiophene by Polycondensation

A novel poly(quinquethiophene) partially containing 3,4-ethylenedioxythiophene (EDOT) and 3-hexylthiophene, poly(3,3 ''''-dihexyl-3',4',3''',4'''-diethylenedioxy-2,2':5',2'':5'',2''':5''',2''''-quinquethiophene), was synthesized by three types of polycondensations. Among them, direct C-H coupling reaction gave the polymer with the highest molecular weight. The resulting polymer was soluble in common organic solvents. Absorption and fluorescence spectra of the polymer showed a remarkable red-shift compared with the corresponding monomer due to the expansion of effective π-conjugation length.

Metallic Interaction in Polythiophene-Ti Plasma Composites

This work presents a study about the structure and morphology of thin plasma composite films of polythiophene (PTh) with metallic particles of Ti (PTh-Ti). The objective was to study the water affinity and electric conductivity in PTh with the addition of metallic phases. The hydrophilicity was studied with the contact angles formed between water and surfaces, and the electric conductivity was calculated with the resistance measured in a two-probe device. The structure and morphology of the composites were studied with X-ray diffraction and scanning electron microscopy. The results indicated that PTh-Ti formed thin films of hybrid composites with oxidized Ti and Fe additional particles released from the electrodes used in the syntheses. The metallic fraction resulted in 2 diffraction angles at 31.6° and 66.1° product of the complex interaction among Ti, resembling orthorhombic TiO2 structures, and PTh. The metallic particles and iodine, added as a dopant to the composites to increase conductivity, reduced the hydrophilicity with water in a competition between roughness and chemical composition. In these conditions, the contact angles resulted between 46° and 75°. The electric conductivity was about 10-6 S/m increasing one order of magnitude with the metallic fraction. However, the high resistance of the polymeric fraction apparently dominates the transference of charges.

Meyer-Neldel Rule in Plasma Polythiophene Thin Films

In polymers, the electronic activation energy depends on the fragmentation, crosslinking, dopants, moisture and in general on the structure-environment interaction. This has a special importance in plasma polymers because fragmentation and crosslinking are usually higher than in other polymers. In this work, DC electrical conductivity of polythiophene thin films prepared by plasma (pPTh) was studied using the Meyer-Neldel (MN) rule to calculate the characteristic MN energy and temperature as a function of moisture and metallic dopants. The experimental data for pPTh synthesized in different conditions indicated that EM = 32 meV and TM = 373 K, suggesting a thermally activated conduction mechanism;however, in polymer-metal matrices with metal concentration higher than the percolation threshold, the conduction mechanism is different causing that the MN rule was only partially fulfilled. The congruence of the experimental data with the multiexcitation entropy model is discussed.