Coordination polymers, 2. Effect of iodine doping on electrical properties of coordination polymers derived from terephthalaldehyde bis(S-benzyldithiocarbazate)

The electrical properties of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) chelate polymers of terephthalaldehyde bis(S-benzyldithiocarbazate) (TBDTC) have been studied. Similarly, different concentrations of iodine were doped to these chelate polymers to increase their conductivity for producing a new class of electrical conductive material. The current interest in doping of iodine in chelate polymers is to a great extent due to their possible application in power sources and electrochemical devices. Electrical conductivity of chelate polymers and iodine doped chelate polymers have been studied over a wide range of temperature (～ 300?450 K). From the electrical conductivity of these polymers activation energies of electrical conduction have been evaluated. A comparison of electrical conductivity and activation energy of electrical conduction of simple and iodine doped polymers has been made and conclusions about the role of iodine in chelate polymers regarding the electrical conductivity have been drawn.     

XPS and ESR studies of electrochemically synthesized polycarbazole post‐doped with iodine

Polycarbazole powders obtained by electrochemical oxidation of carbazole thin films or of carbazole in solution in the electrolyte have been post‐doped with iodine and characterized by room temperature electrical conductivity, X‐ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR). Similar results are obtained with polymers saturated with iodine at room temperature after 6 weeks and with polymers doped at 383 K for 24 h. The polymers obtained from carbazole thin films have a higher electrical conductivity (ς ∼ 10⁻⁴ Ω⁻¹ cm⁻¹) and a higher spin density (9.9 10²¹ spins mol⁻¹ g⁻¹), which corresponds to 71 atom % of ionic iodine. The polymer radicals are located on the nitrogen, and the percentage of N⁺ is 40 atom %. The electrical conductivity of the polymers obtained from carbazole in solution in the electrolyte is two order of magnitude smaller. The percentage of N⁺ is only 25 atom % with an ionic iodine percentage of 13 atom %. So, the most important parameter is not the iodine percentage introduced after doping into the polymers but the percentage of ionic iodine present in the polymers. The differences that are put in evidence can be explained by a better polymerization efficiency of the carbazole when it is deposited on thin film form by vacuum evaporation before electrochemical oxydation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 115–124, 1999     

CHEMICAL DOPING OF TRIPHENYLAMINE-BENZALDEHYDE POLYMERS

A series of different benzaldehydes-4-tolyldiphenylamine polymers has been oxidized by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetrachloro-1,4-benzoquinone (p-chloranil), and also doped by 10-camphorsulfonic acid in order to increase their conductivity. The doped polymers were characterized by ¹H NMR spectroscopy, cyclic voltammetry, UV, and IR spectroscopy. It was found by ¹H NMR spectroscopy that the oxidation yield increased with the increased amount of oxidation agent. It was shown that optical and electrochemical bandgaps of the polymers decreased after oxidation. Conductivity measurements revealed that the applied oxidation and doping procedure resulted in decreased electrical resistance of their initial polymers, down to the level of semiconducting materials. An increased thermal stability of the polymer after oxidation was confirmed by differential scanning calorimetry.     

Synthesis and Characterization of Poly(o-anisidine) Doped with Polymeric Acids

ABSTRACT

Conducting poly(o-anisidine) doped with polymeric acids [viz, poly(styrene sulphonic acid) (PSSA), poly(vinyl sulphonic acid) (PVSA) and poly(acrylic acid) (PAA)] was synthesized by in-situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is a single-step polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The polymers were characterized by using UV-Vis., FT-IR spectroscopy, thermal analysis, and conductivity measurements. Formation of mixed phases of polymer together with conducting emeraldine salt phase are confirmed by spectroscopic techniques. Thermal analysis shows that PAA doped poly(o-anisidine) undergoes three stage decomposition pattern similar to unsubstituted polyaniline. While, in PSSA and PVSA, doped sample splitting up of the second weight loss stage is observed leading to a four-step decomposition pattern. Room temperature conductivity measurements show less conductivity in poly(o-anisidine) than in polyaniline, due to the cumulative steric as well as electronic effects of the bulky methoxy substituent present at ortho position on the benzene ring. Increase in conductivity with increase in temperature is observed by high temperature conductivity measurements, showing “thermally activated behavior.”     

Shape memory polyester-based nanomaterials: cutting-edge advancements

ABSTRACT

Shape memory polymers have gained immense importance across technical industries ranging from aerospace and electronics to biomedical fields. This article presents state-of-the-art overview of versatile shape memory polyesters and derived nanocomposites. Shape memory polyesters such as polylactic acid, polyhydroxyalkanoate, polycarbonate, and polyester blends have been identified. Shape memory polyesters have also been reinforced with nanoreinforcements including fullerene, graphene, carbon nanotube, and polyhedral oligomeric silsesquioxane (POSS). Consequently, different groups of stimuli-responsive polyester nanocomposites have been discussed such as polyester/graphene, polyester/carbon nanotube, polyester/fullerene, and polyester/POSS. Future development of shape memory polyesters may reveal superior electrical, mechanical, and thermal performance for technical applications.     

Synthesis,characterization, and comparison of self‐doped,doped, and undoped forms of polyaniline,poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)]

Polyaniline (PANI), poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)] were synthesized by chemical oxidative polymerization with ammonium persulfate as an oxidizing reagent in an HCl medium. The viscosities, electrical conductivity, and crystallinity of the resulting polymers (self‐doped forms) were compared with those of the doped and undoped forms. The self‐doped, doped, and undoped forms of these polymers were characterized with infrared spectroscopy, ultraviolet–visible spectroscopy, and a four‐point‐probe conductivity method. X‐ray diffraction characterization revealed the crystalline nature of the polymers. The observed decrease in the conductivity of the copolymer and poly(o‐anisidine) with respect to PANI was attributed to the incorporation of the methoxy moieties into the PANI chain. The homopolymers attained conductivity in the range of 3.97 × 10^?3 to 7.8 S/cm after doping with HCl. The conductivity of the undoped forms of the poly[aniline‐co‐(o‐anisidine)] and poly(o‐anisidine) was observed to be lower than 10^?5 J/S cm^?1. The conductivity of the studied polymer forms decreased by the doping process in the following order: self‐doped → doped → undoped. The conductivity of the studied polymers decreased by the monomer species in the following order: PANI → poly[aniline‐co‐(o‐anisidine)] → poly(o‐anisidine). All the polymer samples were largely amorphous, but with the attachment of the pendant groups of anisidine to the polymer system, the crystallinity region increased. The undoped form of poly[aniline‐co‐(o‐anisidine)] had good solubility in common organic solvents, whereas doped poly[aniline‐co‐(o‐anisidine)] was moderately crystalline and exhibited higher conductivity than the anisidine homopolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Temperature dependence of electrical conduction in pure and doped polypyrrole

Summary Pure polypyrrole and polypyrrole in salt form were synthesized using NaOH as reducing agent in aqueous HCl, respectively. Electrical conduction in these pure and doped polypyrrole samples was studied through the I-V characteristics of these materials. I-V characteristic curves for both pure and doped polypyrrole were found to be linear. The conductivity of chlorine-doped polypyrrole is about 10⁴ times that of pure polypyrrole. An attempt has been made to study the dependence of conductivity on temperature, in order to understand the application of these systems. It has been observed from the variation of conductivity vs. temperature curve in both the samples that the conductivity increases with the increase in temperature. This behaviour is indicative of semiconducting nature of the samples with a variation in electrical conductivity of each, which is a strong function of doping and temperature of the environment. Activation energies for both the samples have been found to be in millielectron-volt range, 101.94 meV and 121.68 meV for pure and doped polypyrrole, respectively. An effort has also been made to understand the charge transport in these conductive polymers through models.     

Arylidene polymers. XVIII. Synthesis and thermal behavior of organometallic arylidene polyesters containing ferrocene derivatives in the main chain

A new interesting category of organometallic polyesters based on diarylidenecycloalkanones containing ferrocene derivatives in the polymer main chain has been prepared by interfacial polycondensation of 1,1′-dichlorocarbonyl ferrocene or 1,1′-dichlorocarbonyl-4,4′-diiodoferrocene with 2,5-bis(p-hydroxybenzylidene)cyclopentanone, 2,5-divanillylidenecyclopentanone, 2,6-bis(p-hydroxybenzylidene)cyclohexanone, 2,6-divanillylidenecyclohexanone, and 2,7-bis(p-hydroxybenzylidene) cycloheptanone. The resulting polyesters were characterized by elemental analyses, infrared spectroscopy, solubility, and viscometry measurements. The thermal behavior of the synthesized polymers was evaluated by thermal gravimetric analysis and correlated with their structures. The crystallinity of all polymers were examined by x-ray diffraction analysis. Moreover, the electrical conductivity of a selected example of polymer was investigated above the temperature range (300–500 K) and showed that it followed an Arrhenius-type equation with activation energy 2.09 eV. © 1993 John Wiley & Sons, Inc.     

Electrical behavior of polycarbonate doped with nickel chloride

The dc electrical conductivity (σ) and permittivity (ε′) of polycarbonate (PC) discs doped with different concentrations of NiCl₂ are studied. Both (σ) and (ε′) increase with increasing the concentration of NiCl₂, with a maximum value at 30 wt %. The activation energies for pure and doped PC are 0.49 and 0.53 eV, respectively. The increase in the electrical conductivity with increasing NiCl₂ concentration is attributed to the formation of chargetransfer complexes (CTC); the increase in ε′ may be due to the rise in the interfacial polarization which results from the increase in boundaries between PC and NiCl₂ phases. The currents in PC discs, both pure and doped with NiCl₂, in the high-field region are attributed to space charge limited conduction. The time dependence of conduction current before and after reversal of applied voltage is also investigated. Some parameters such as the density of mobile ions and their drift mobilities are estimated. © 1995 John Wiley & Sons, Inc.     

Electrically conductive composites prepared from 3-methyl thiophene by the FeCl3 oxidation method

Surface conductive polyurethane films from poly(propylene glycol), toluene 2,4-diisocyanate, 3-methyl thiophene and butyltin dilaurate can be successfully prepared by the diffusion-oxidative polymerization method. Various effects of the doping conditions, such as the reaction time, the FeCl₃ concentration, the weight ratio of the 3-methyl thiophene to PU and the temperature on the electrical conductivity and thickness of the conductive layer of the 3-methyl thiophene/PU composite were investigated. Decomposition temperature rises gradually from pure undoped PU to doped composite that indicates blending took place in FeCl₃/ethyl acetate solution. As oxidative reaction time increases, the electrical conductivity of the 3-methyl thiophene doped PU film increases together with the thickness of the coating layer. With increasing FeCl₃ concentration and weight ratio of the 3-methyl thiophene to PU, the thickness of the coating layer decreases, while the electrical conductivity increases. The increase of the thickness of the PU film leads to the rise of the electrical conductivity. The thickness of the coating layer decreases, while the electrical conductivity of the 3-MT doped PU film increases with increasing reaction temperature. As the reaction time and temperature increase, the polar components of the PU film increase resulting into the increase of moisture regain value.     

The effect of Fe2+ state in electrical property variations of Sn‐doped hematite powders

The structural, electrical, and chemical properties of Sn‐doped Fe₂O₃ powders were investigated. Various quantities of Sn‐doped Fe₂O₃ powders were synthesized using solid‐state reactions. Rietveld analysis for the powders that were doped below 2% revealed a phase‐pure Sn‐doped Fe₂O₃ structure (i.e., identical to Fe₂O₃ structure). Alternatively, the analysis for the powders that were doped more than 3% exhibited secondary phase. The unit cell volume and electrical conductivity of the phase‐pure samples increased with an increase in the doping concentration. X‐ray photoelectron spectroscopy measurements showed an increased Fe²⁺ state with the increase in Sn doping concentration. Therefore, the improved electrical conductivity and unit cell volume with the increase in doping concentration of the phase‐pure powders might be related to the increased Fe²⁺ state.     

Development of whey protein isolate/polyaniline smart packaging: Morphological,structural, thermal,and electrical properties

Development of smart packaging from biodegradable polymers that allow monitoring food exposure conditions is important to reduce food and material packaging waste. The objective of this article is to evaluate the conductivity of polyaniline (PANI) in its doped form with dodecylbenzene sulfonic acid on morphological, structure, thermal, and electrical (Hall effect) properties of whey protein isolate (films. Films show immiscible with 10⁻³ S cm⁻¹ conductivity and semiconductor behavior due to a phase separation that is observed (scanning electron microscopy and thermogravimetric analysis). Fourier transform infrared and Raman spectra do not present changes in relation to control samples, suggesting no chemical interaction with polymers. This result is probably due to deprotonation of PANI. No significant differences are observed for conductivity of film made above 60 mg mL⁻¹ of PANI. Films showed semiconducting properties that allow a new application on smart packaging to help monitor electrical properties of foods in processes of degradable. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47316.     

Photoluminescence,FTIR, and electrical characterization of samarium(III) chloride‐doped polyaniline

The synthesized polyaniline (PANI) is doped with different concentrations of Samarium(III) chloride (SmCl₃). The electrical conductivity of doped PANI samples has been measured in the temperature range (300–400K). It has been found that dc conductivity increases with the increase of dopant concentration. Different parameters, based on the conductivity, such as pre‐exponential factor (σ₀) and activation energy (ΔE) have also been calculated. These parameters exhibit information about the nature and suitability of the dopant. Doped samples are characterized by FTIR and photoluminescence studies, which show the interaction of dopant with PANI. Two sharp peaks of different intensities from PL spectra at 388 and 604nm have appeared in doped PANI, which might be due to the effect of SmCl₃. It has been observed that SmCl₃ (dopant) shows noticeable changes in the electrical and spectroscopic properties of doped PANI. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrical conductivity of plasma-treated poly(p-phenylene sulfide) doped with iodine

Plasma treatment of poly(p-phenylene sulfide) (PPS) doped with I₂ is found to increase both the electrical conductivity and the stability of the material. The average conductivity of plasma-treated samples reaches an apparently saturated value of 1.7 × 10^?3s cm^?1, which is about six orders of magnitude higher than that of the same material without plasma treatment, and this conductivity remains practically unchanged under exposure to ambient environment for 10 days. Infrared and secondary ion mass spectra of the samples before and after plasma treatment suggest that the charge-transfer complexes are formed in PPS doped with I₂ after plasma treatment. This is also consistent with the temperature dependence of conductivity results which show that the activation energy for electrical conduction decreases from 2.0 eV for pure PPS to 0.2 eV for plasma-treated I₂-doped PPS. Using isothermal potential and current decay techniques, we have also measured the trap density distribution. Plasma treatment, on the one hand, does create more traps in PPS, but, on the other hand, it enhances conductivity. The mechanism of electrical conduction is briefly discussed.     

Repeat Unit Structure and Gas Transport Properties of Aromatic Polymers

Abstract

Structure/transport-property correlations for a family of aromatic polyesters and polyphenylene oxides are presented. How modification in repeat unit structure changes the packing of bulk polymers, and subsequently the solubility and diffusivity of gases in polymers is addressed in detail. In addition to polymer-gas attraction, polymer packing density is proposed to be an important factor in determining the gas-absorbing capacity of glassy polymers. The observed diffusivity data are strongly correlated with polymer packing. Moreover, scatter in the correlation can be satisfactorily attributed to differences in local chain mobility among the polymers investigated here.     

Synthesis and characterization of new unsaturated polyesters containing cyclopentapyrazoline moiety in the main chain

3‐p‐Hydroxyphenyl‐6‐p‐hydroxybenzylidene cyclopentapyrazoline (III) and 3‐vanillyl‐7‐vanillylidene cyclopentapyrazoline (IV) were used as new starting materials for preparing new unsaturated polyesters. The polyesters were prepared by reacting (III) or (IV) with adipoyl, sebacoyl, isophthaloyl, and terephthaloyl dichlorides utilizing the interfacial polycondensation technique. The polyester samples have been characterized by elemental and spectral analyses. The polyesters have inherent viscosities of 0.55–0.97 dL/g. All the polyesters are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in concentrated sulfuric acid. Their glass transition temperatures (T_g) range from 103.34 to 208.81°C, and the temperatures of 10% weight loss as high as 190 to 260°C in air, indicating that these aromatic polyesters have high T_g and excellent thermal stability. Doping with iodine dramatically raised the conductivity and produced dark brown colored semiconductive polymers with a maximum conductivity in the order of 3.1 × 10^?7 Ω^?1 cm^?1. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Conductive polymeric compositions

In most low-strength applications, plastics offer cost, maintenance, and density advantages over metals. Major deficiencies of plastics, however, are low thermal and electrical conductivities. Various studies have dealt with these problems, and it has been found that thermal conductivity and electrical conductivity can both be increased by the addition of conductive fillers to the polymer. The two parameters that most significantly affect the increase in conductivity of the resulting composite are volume loading of filler and filler shape. Fibrous conductors improve conductivity much-more significantly than spheres, flakes, or irregular particulates. The effect of fillers on thermal and electrical conductivities is not the same. The maximum increase in thermal conductivity that can reasonably be expected over the base polymer is 100:1. Electrical conductivity, on the other hand, can be increased by a factor of 10¹⁵. One particularly attractive technique for increasing the electrical conductivity of polymers is electroless plating of metals onto glass fibers which are then incorporated into the polymer. Such a composite can he made electrically conductive with as little as 6 volume percent metal.     

Study of polyaniline polyacrylamide composites by positron annihilation technique

Polyaniline doped with nonoxidizing Bronsted acids is recognized as a conducting material, as its electrical conductivity changes with percentage of doping. In the present work, different percentages of doped polyaniline were blended with polyacrylamide and their electrical conductivities as well as the positron annihilation lifetimes were measured. Analysis of data yielded three lifetime components. It was observed that the value of the short lifetime component remained constant for doping concentration, whereas that of the intermediate component τ₂ decreased. The relative intensity pertaining to τ₂, however, increased with the increase in doped PANI concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 930–933, 2003     

Liquid phase synthesis of aromatic poly(azomethine)s,their physicochemical properties,and measurement of ex situ electrical conductivity of pelletized powdered samples

Aromatic bis-aldehydes have been used as building blocks in the synthesis of polyazomethines (a class of conjugated Schiff bases) and their physicochemical properties have been studied. Six dialdehydes have been synthesized, 3a-3f, via etherification reaction between aromatic diols (2a-2f) and 4-fluorobenzaldehyde (1) (see Scheme 1), and then polymerized with 1,4-phenylenediamine (4a) and 4,4′-oxydianiline (4b) (see Scheme 2). The chemical structures of the bis-aldehydes were elucidated by FTIR, ¹H NMR and ¹³C NMR spectroscopic studies, elemental analysis and single crystal whereas the polymers were studied by FTIR and NMR spectroscopy. Their physicochemical properties were examined by their inherent viscosity, organosolubility, differential scanning calorimetry, X-ray powder diffraction, thermogravimetric analysis, solvatochromism, and photoluminescence. We report the electrical conductivity of each polymer measured by the four probe method. The results indicate that the electrical conductivity of polymers lies in range 0.019–0.051 mScm^?1 which is reasonably higher than any reported value.     

Thermoelectric performance of electrodeposited nanostructured polyaniline doped with sulfo‐salicylic acid

Conducting polymers, in present days, are considered to be potential thermoelectric (TE) materials. Among them polyaniline (PANI) is a promising candidate. Nanostructured polyaniline doped with organic dopant is electrodeposited and structurally characterized. Its transport properties are investigated for thermoelectric applications. The analysis of transmission electron microscopy image reveals that the sample is rod like nanostructure. This study shows that the type (inorganic/organic) of dopants plays an important role to influence the dimension of nanostructure and the electrical transport properties of PANI. In this study, organic dopant sulfosalicylic acid is proposed for enhancement of figure of merit through an increase in thermoelectric power and decrease in thermal conductivity. Compared to our earlier work the figure of merit evaluated is two orders higher than that of the inorganic dopant bismuth nitrate doped PANI. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39920.