Microwave synthesis: An alternative approach to synthesize conducting end-capped polymers

Within this study microwave assisted syntheses of functionalized polystyrene (PS), via ATRP, and tetra-aniline (TANI) end-capped polymers are demonstrated. Compared to conventional heating, microwave irradiation process in pulsed mode shows the feasibility of conducting end-capped polymers synthesis with no degradation, strong acceleration of polymerization rate and coupling reaction, controlled size and chemical formulation. Conducting polymers with controlled architectures in terms of molecular size of both the insulating (PS) and the conducting (TANI) moieties show a conductivity above 10⁻¹ S cm⁻¹ when containing 2 wt% TANI while composites of PS and TANI exhibited a conductivity of ca 10⁻⁵ S cm⁻¹ when containing more than 7 wt% TANI.     

导电高分子在雷达吸波材料中的应用研究进展

导电高分子具有密度低、结构多样化、可分子设计、电磁参量可调等独特的优点,符合雷达吸波材料"(涂层)薄、(质量)轻、(吸收频带)宽、(吸收能力)强"的发展要求,是极其有发展前景的新型雷达吸波材料。本文首先介绍了雷达吸波材料的吸波原理和导电高分子的一些基本知识,然后结合目前导电高分子材料在雷达吸波材料领域的研究状况,指出了导电高分子未来在雷达吸波材料中的研究方向。     

‘Stuffed’ conducting polymers

Conducting polymers (CP) obtained by oxidative polymerization using iron(III) salts shrink when Fe(II) and the excess counter ions are washed out after polymerization. This phenomenon can be used to incorporate active molecules into the CP matrix via their addition to the wash liquid. In the present work we demonstrate this principle on three different CP's: polypyrrole (PPy), poly-terthiophene (PTTh) and poly(3,4-ethylenedioxy thiophene) (PEDT), using ferrocene as a model molecule to be trapped in the polymer films.     

导电聚合物复合材料作为超级电容器电极材料

本文综述了基于导电聚合物的复合材料(导电聚合物/碳材料、导电聚合物/金属氧化物材料、导电聚合物/碳材料l金属氧化物材料)作为电极材料在超级电容器中的应用进展,指出将导电聚合物与碳材料或金属氧化物复合,双电层电容与法拉第准电容结合,有机材料与无机材料结合,是超级电容器电极材料研究的重要发展方向.     

噻吩类导电高聚物的研究进展

噻吩类聚合物是研究较为广泛的功能高分子材料。详述了通过化学氧化聚合法和电化学氧化聚合法所合成的噻吩类导电聚合物的性能和用途,常用的结构与性能表征方法以及噻吩类导电聚合物在光、电、磁等各种领域中的应用。     

Orange to black electrochromic behaviour in poly(2-(2-thienyl)-1H-pyrrole) thin films

We have studied an electrochromic precursor, 2-(2-thienyl)-1H-pyrrole (1), using two improved procedures of the Trofimov reaction. Optimised stereochemical calculations at the B3LYP/6-311G* level showed almost equal s-cis and s-trans conformational populations in 1 with marked out-of-plane deviations of ca. 30°. Model calculations suggest that the predominant rotational conformation in undoped poly(1) would be s-trans with the essential out-of-plane deviations around the all three interheterocyclic bonds of ca. 25-30°. Monomer 1 exhibited two irreversible oxidation processes at +0.86 and +1.3 V corresponding to the oxidation of the pyrrole and thiophene rings, respectively. Orange to black electrochromic behaviour was found in ClO₄⁻ doped poly(1) thin films with colouring and bleaching times of 1.8 and 1.3 s, respectively. The colouration efficiency during the bleaching process was 233 cm²/C. The optical contrast at 450 nm was 19% and in the near-IR was 36%. The band-gap of poly(1) (1.6-1.7 eV) was found to be significantly lower than that of polypyrrole (2.85 eV) and polythiophene (2.3 eV) as a consequence of increased electron delocalisation in the system. Important differences in the morphology of doped and dedoped poly(1) films were observed by atomic-force microscopy (AFM). Doped poly(1) films showed a granular morphology with primary particles of 45-60 nm in size and an average surface roughness of 3.5 nm. On the other hand, dedoped poly(1) films showed interconnected aggregates of 65-90 nm in size as a consequence of particle fusion, with a surface roughness of 9.2 nm. In summary, poly(1) is a promising material for emerging flexible electrochromic devices such as displays and variable optical attenuators.     

Enzymatic oxidation of alkoxyanilines for preparation of conducting polymers

A biomimetic route for synthesis of a conducting molecular complex between polyalkoxyanilines and a polyelectrolyte, poly (sodium 4‐styrenesulfonate) (SPS) is presented. Horseradish peroxidase (HRP) was used to catalyze the polymerization of alkoxyanilines. A few of water‐soluble ring‐substituted polyalkoxyanilines have been enzymatically synthesized with variation of groups, such as ortho‐methoxy, meta‐methoxy, ortho‐ethoxy, and meta‐ethoxy to form polyalkoxyanilines/SPS complexes. The presence of alkoxy substituents affects the polymerization reactions. These enzymatic oxidation reactions occur in a different potential range to that observed for the chemical polymerization. Similar electrochemical and optical properties were obtained for every pair of ortho‐ and meta‐alkoxy substituted polyanilines. For comparing, polyalkoxyanilines were also prepared by chemical polymerization in the presence of SPS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3724–3729, 2007     

Doping front migration in intrinsically conductive polymers and its application

Doping front migration is a recently discovered effect occurring in sandwich structures composed of intrinsically conductive polymers. A system based on chemical or electrochemical doping is capable of controlling an integrated display and modifying the electrical resistance of the conductive polymer. The effect does not require a battery and is capable of monitoring time and temperature exposure. Low-cost devices using doping front migration could be the basis of a new class of smart labels for applications such as electronic “best before” labels on food and drink.     

Proton‐conducting polymers with reduced methanol permeation

The permeability of Nafion®117 and some types of acid‐base and covalently crosslinked blend membranes to methanol was investigated. The methanol crossover was measured as a function of time using a gas chromatograph with a flame ionization detector. In comparison to Nafion, the investigated acid‐base and covalently crosslinked blend membranes show a significant lower permeation rate to methanol. Additionally, another method to reduce the methanol permeability is presented. In this concept a thin barrier layer is plasma polymerized on Nafion 117 membranes. It is shown that a plasma polymer layer with a thickness of 0.3 µm reduces the permeability to methanol by an order of magnitude. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 67–73, 1999     

Laccase‐catalyzed synthesis of conducting polyaniline‐lignosulfonate composite

Enzymatic polymerization of aniline was first performed in lignosulfonate (LGS) template system. High‐redox‐potential catalyst laccase, isolated from Aspergillus, was used as a biocatalyst in the synthesis of conducting polyaniline/lignosulfonate (PANI‐ES‐LGS) complex using atmospheric oxygen as the oxidizing agent. The linear templates (LGS), also serving as the dopants, could facilitate the directional alignment of the monomer and improve the solubility of the conducting polymer. The process of the polymerization was monitored using UV‐Vis spectroscopy, by which the conditions for laccase‐catalyzed synthesis of PANI‐ES‐LGS complex were also optimized. The structure characterizations and solubility of the complex were carried out using corresponding characterization techniques respectively. The PANI‐ES‐LGS suspensions obtained was used as coating for cotton with a conventional padder to explore the applications of the complex. The variable optoelectronic properties of the coated cotton were confirmed by cyclic voltammetry and color strength test. The molecular weight changes of LGS treated by laccase were also studied to discuss the mechanism of laccase catalyzed aniline polymerization in LGS template system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42941.     

Adsorption behavior of monomers and formation of conducting polymers on polyester fibers

In situ adsorption of monomers on fibers plays a key role in fabricating highly conductive polyaniline (PANI)‐based textiles by two‐stage oxidation polymerization. Experiments were conducted in aniline monomer and hydrochloric acid solution with the variables such as contact time, initial concentration, and temperature, which can enhance the equilibrium adsorption capacity to aniline of poly(ethylene terephthalate) (PET) fibers. Equilibrium data were fit well by a Henry partition‐type isotherm equation. It was found that the kinetics of the adsorption of aniline onto PET fibers at different operating conditions was best described by the pseudo‐second‐order model. The rate parameters of the intraparticle diffusion model for adsorption were also evaluated and compared to identify the adsorption mechanisms. The monomer exhaustion increased with increasing the temperature. The value of electrical surface resistance of conductive textiles about 3.2 kΩ was obtained when the padder squeeze step was introduced, and the molar ratio of 0.6 between the oxidant concentration and the exhausted concentration of monomers at the adsorption equilibrium was applied. Scanning electron micrographs of PANI/PET composite surfaces were observed, conforming that smooth films were produced by surface polymerization of aniline monomers adsorbed previously on fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrosynthesis of valuable conducting polymers from the anodic coupling of β-substituted oligothiophenes

Electrochemical polymerization of thiophene oligomers (n = 4) bearing an hexamethylenic ω-methoxy functionalized side chain at the 3-3″′ position of the thiophene rings, was performed in different solvents and electrode surfaces. The degree of polymerization and the electrochemical behaviour of the different electrosynthetized polymers were compared with a polymer obtained by a chemical method. The polymeric films were characterized using cyclic voltammetry, FT-IR, AFM and SEM microscopy.     

Thermally stable conducting composites based on a carbon black‐filled polyoxadiazole matrix

New thermally stable conducting materials can be obtained by dispersing conducting carbon black into poly(4,4′‐diphenylether‐1,3,4‐oxadiazole) (POD–DPE) solution in NMP. The blend preparation process resulted in quite good dispersed composite and a relatively low percolation threshold (around 5 wt % of CB). The effect of the compressive stress on the resistivity of composite has been evaluated. The resistivity decreases continuously as the applied pressure is increased. In addition to the electrical conductivity, the presence of carbon black resulted in higher thermally stable materials. The thermal stability, electrical conductivity, and pressure‐sensible characteristics make this conducting material a good candidate for application in manufacture of pressure sensors for high temperature ambient. This material shows a typical semiconductor behavior, characterized by an increase of conductivity with the temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1631–1637, 2004     

New polymer syntheses part: 54 novel conducting polymers and copolymers based on 4‐Teriary butyl‐cyclohexanone moiety in the main chain

A new interesting class of conducting polymer and copolymers based on 4‐teriary butyl‐cyclohexanone in the main chain has been synthesized by solution polycodensation of terephthalaldehyde with 4‐teriary butyl‐cyclohexanone and/or cycloalkanone derivatives. The model compound I was synthesized from the 4‐teriary butyl‐cyclohexanone with benzaldehyde, and its structure was confirmed by elemental and spectral analyses. The resulting polymer and copolymers were characterized by elemental and spectral analyses including Fourier transform infrared spectrometer (FT‐IR) and nuclear magnetic resonance (¹H‐NMR), beside solubility and viscometry measurements. The thermal properties of those polymer and copolymers were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) measurements and correlated to their structural units. X‐ray analysis showed that it has some degree of crystallinity in the region 2θ = 5–60°. The UV–visible spectra of some selected polymers were measured in dimethyl sulfoxide (DMSO) solution and showed absorption bands in the range 253–398 nm, due to n–π* and π–π* transition. The morphological properties of selected examples were tested by scanning electron microscope (SEM). Moreover, the electrical conductivities and the doping with iodine were tested. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

X-ray photoelectron spectroscopy of conducting polyaniline and polyaniline–polystyrene blends

Conductive polyaniline solutions were chemically prepared using bis (2-ethylhexyl) hydrogen phosphate (DiOHP) as the dopant chemical species. The codissolution method leads to conductive polyaniline–polystyrene (PANI–PSt) composites with good mechanical properties. The electronic structure of both conducting PANI films and PANI–PSt blends was investigated by X-ray photoelectron spectroscopy, which allowed one to quantify the proportion of benzenoid amine, quinoid imine, and protonated units. Blending polyaniline with PSt does not involve important modifications in the polymer electronic structure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1209–1214, 1998     

Electrically conducting polyaniline‐PBMA composite films obtained by extrusion

Poly(n‐butyl methacrylate) (PBMA)–polyaniline (PANI) composite films were obtained by extrusion by use of two methods: the first method consisted of polymerizing a thin layer of PANI, with Cl^? as dopant, on the extruded film of PBMA; the second method was based on blends of PBMA and PANI produced by the extrusion of the two polymers by using dodecylbenzene sulfonic acid (DBSA) as dopant. The thermal properties, electrical conductivity, and morphology of the composite films obtained were measured. The sensitivity of the composites films as detectors of hydrogen peroxide and ammonia was evaluated. The change in the electrical resistance on exposure to different aqueous solutions of these components shows a linear behavior. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 179–183, 2003     

Electrical and mechanical characteristics of composites consisting of fractionated poly(3‐hexylthiophene) and conducting particles

The dynamic viscoelasticity of fractionated poly(3‐ hexylthiophene)titanium carbide (P3HT/TiC) composites was examined with regard to their electrical characteristics. The elastic modulus (E′) at 0°C [i.e., near the glass‐transition temperature (T_g) of P3HT] increased with increasing TiC content of the composite. In particular, composites whose TiC content exceeded the threshold concentration showed a high E′. This was caused by the high E′ of TiC and the strong interaction between TiC and P3HT. When the sample was heated above the T_g, E′ decreased rapidly and an increase in the loss tangent appeared near the T_g of P3HT. Mechanical loss was caused by friction between TiC and P3HT. The change in mechanical characteristics affected the electrical conductivity. When the TiC content of the composite approximated to the threshold concentration, a significant change in mechanical characteristics took place, so that a large positive temperature coefficient (PTC) effect was observed near the T_g. To explain the PTC phenomenon, we propose a model of conductive pathway for P3HT/TiC. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1429– 1433, 2002     

Low‐potential electrochemical polymerization of 6‐nitroindole and characterization of its polymers

Conducting polymers bearing nitro substituents are very important from both academic and industrial viewpoints. However, it is very difficult to electrosynthesize such conducting polymers because of the strong electron‐withdrawing effect of nitro groups. In this article, we describe the electrochemical synthesis of films of a new conducting polymer, high‐quality poly(6‐nitroindole) (P6NI), by direct anodic oxidation of 6‐nitroindole in boron trifluoride diethyl etherate containing 10% (v/v) diethyl ether. The oxidation potential onset of 6‐nitroindole in this medium has been measured to be just 0.98 V versus a saturated calomel electrode (SCE), which is much lower than that determined in acetonitrile containing 0.1 mol/L tetrabutylammonium tetrafluoroborate (1.6 V vs SCE). Thermal studies have revealed that P6NI displays good thermal stability. The electrical conductivity of the P6NI films has been measured to be 0.08 S/cm. Structural studies have shown that the polymerization of the 6‐nitroindole ring occurs mainly at the 2,3‐positions. Fluorescence spectral studies have shown that the principal excitation and emission peaks of P6NI are at 416 and 535 nm, respectively, with a fluorescence quantum yield of 0.05. All these properties of P6NI films may facilitate their potential applications in various fields, such as electrochemical sensors and green‐light‐emitting materials. To the best of our knowledge, this is the first report on the electrosynthesis and characterization of 6‐nitro‐substituted polyindole films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Chemical preparation of conducting polyfuran/poly(2‐chloroaniline) composites and their properties: A comparison of their components,polyfuran and poly(2‐chloroaniline)

Conductive homopolymers and composites of poly(2‐chloroaniline) (P2ClAn) and polyfuran (PFu) were synthesized chemically in hydrous and anhydrous media, and their properties were investigated. The polymers and composites were characterized by Fourier infrared spectroscopy, ultraviolet‐visible absorption spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, magnetic susceptibility, and conductivity measurements. It was found that the PFu/P2ClAn composite is thermally more stable than both the P2ClAn/PFu composite and the homopolymers. It was determined from Gouy scale measurements that conducting mechanisms of homopolymers and composites are polaron and bipolaron in nature. It was observed that the conductivity and magnetic susceptibility values changed with a changing amount of the guest polymer in the prepared composites. The conductivity (3.21 × 10^?2 S/cm) of the P2ClAn/PFu (55.8% m/m) composite was found to be higher than the conductivities of both homopolymers (σ_PFu = 1.44 × 10^?5 S/cm; σ_P2ClAn = 1.32 × 10^?3 S/cm). It was determined that the composites synthesized had different conductivities and morphological and thermal properties from changing synthesis order. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2924–2931, 2003     

Synthesis and characterization of conducting polyaniline‐activated carbon nanocomposites

Conducting polyaniline (PAni)/activated carbon (AC) nanocomposites were synthesized by the in situ chemical polymerization method. The resultant shell–core PAni–AC nanocomposites were characterized by elemental analysis, Fourier transform infrared, scanning electron microscopy, thermal gravimetric analysis, X‐ray diffraction, and transmission electron microscopy. We did not observe any significant chemical interaction between the PAni and AC, only core–shell coupling between the AC and the tightly coated polymer chain was revealed. Measurement of the physical properties showed that the incorporation of conducting PAni on to AC particles during chemical synthesis increased electrical conductivity and thermal stability by several orders of magnitude to that of the pristine PAni powders. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1973–1977, 2007