Polyaniline Backbone Research Articles

A highly effective PANI@(Ce-Er) dual doped ZnO (PCEZ) nanocomposite as UV-light driven photocatalyst for degradation of MB dye: synthesis and characterization

Utilizing ecologically friendly methods to address wastewater concerns is paramount. In this study, we developed novel PANI@(Ce-Er) dual-doped ZnO (PCEZ) nanocomposites using a wet impregnation approach assisted by ultrasound. These composites were thoroughly characterized using XRD, FESEM, EDX, UV-DRS, PL, and Impedance Analyzer techniques to assess their structural, optical, and electrical properties. Structural characterization was conducted to analyze the crystalline behavior and chemical composition of the synthesized samples. UV-DRS and PL spectroscopy were utilized to analyze their optical properties. Compared to PANI alone, the PCEZ heterojunction demonstrated enhanced photocatalytic stability and efficiency. Notably, in neutral media, the PCEZ heterojunction exhibited a significant photodegradation efficiency against methylene blue (MB), achieving approximately to 90.13% degradation. Morphology analysis of the synthesized samples and elemental composition was effectively performed using SEM images and EDX data. The UV-DRS investigation aimed to confirm the active contacts of dopant metals with polyaniline backbone chains and assess the energy band gap, which defines the absorption behavior of the photocatalyst. Kinetic studies of methylene blue degradation were characterized using the Pseudo First-Order relation, with the best adjusted R2 value of 0.9947 observed for 50% w/w (PANI@(Ce-Er)-ZnO). The produced PANI@(Ce-Er) dual-doped ZnO nanocomposites show promise as effective photocatalyst for the elimination of methylene blue in aqueous environments.

Structural and electrical conductivity studies of Polyaniline - WO3 hybrid nanocomposites for gas sensing applications

Abstract Conducting polymer – metal oxide based hybrid nanocomposites are a fascinating class of materials for miniaturized and flexible gas sensor devices. They exhibit enhanced physiochemical properties such as sensitivity, selectivity towards various volatile and hazardous chemical and bioanalytes. Our study focuses on conducting polyaniline (PANI) and WO3 nanocomposites, where different weight percentages (wt.%) of WO3 nanoparticles are embedded within the conducting PANI matrix using an in-situ oxidation polymerization synthesis technique. The surface morphology analysis indicated that the WO3 nanoparticles with an average grain size of ~200 nm are homogeneously distributed within the PANI nanofibers. The Fourier Transform Infra-Red (FTIR) spectrum analysis showed that the absorption peaks at 1111,1291, 1385, 1474, and 1560 cm−1 are typical of the conducting PANI emeraldine phase. We attribute the additional broad peak ranging between 840 to 720 cm−1 in the spectrum to WO3 phase, wherein, the intensity of the peak increases with WO3 content in case of hybrid composites. Current-voltage (I-V) characteristics for all our samples showed linear behaviour up to 1.2 volts. Temperature-dependent DC electrical conductivity (σ) studies measured from room temperature to 120°C for pure PANI, and PANI-WO3 composites showed an enhanced electrical conductivity of values up to 0.12 S/cm for PANI as compared to WO3 with σ ~ 1.4 x 10−3 S/cm. Pure PANI exhibits semiconducting behavior with an increase in electrical conductivity with temperature due to the charge carrier delocalization within the dispersed PANI backbone. The addition of higher concentrations of WO3 in composites leads to a metallic-like behavior, characterized by a decrease in electrical conductivity with temperature. These observations are attributed to the field-assisted band bending effects at the interfaces of PANI and WO3. Our composites show desired electrical characteristics suitable for gas sensing applications.

Novel sulfonated polyaniline/graphene oxide electrode with high cycling stability for all-solid-state flexible supercapacitors

Polyaniline (PANi) has high theoretical specific capacitance by storing energy through redox reactions and thus is widely used in supercapacitors. However, the skeleton of PANi expands and contracts during the process of ion inhalation and exfoliation, which leads to a decrease in electrochemical performance. To solve this problem, we graft the sulfonic acid group onto the PANi backbone via a borate ester bond, which serves as a proton reservoir to provide protons for PANi to undergo redox reactions and provide pseudocapacitance. SPANi is then polymerized in situ on graphene oxide (GO), and its comprehensive performance of the electrode is further enhanced by designing ordered structures and synergistic interactions. The SPANi5/GO5 composite that are created in-situ have a fantastic specific capacitance of 460.56 F g−1 at 1 A g−1 and maintained 85.19% of the primary capacitance after 10,000 cycles. The device is assembled with PAAM/H2SO4/GO as the gel electrolyte, which achieves a specific capacitance of 137.75 F g−1, and the capacitance is retains at 90.74% after 10,000 cycles. The supercapacitor exhibits a large energy density of 13.76 Wh kg−1 when the power density is 200.27 W kg−1. The present study presents a novel and efficient approach for the fabrication of high-performance supercapacitor electrodes.

Fabrication of a tailor-made conductive polyaniline/ascorbic acid-coated nanofibrous mat as a conductive and antioxidant cell-free cardiac patch

Polyaniline (PANI) was in-situ polymerized on nanofibrous polycaprolactone mats as cell-free antioxidant cardiac patches (CPs), providing electrical conductivity and antioxidant properties. The fabricated CPs took advantage of intrinsic and additive antioxidant properties in the presence of PANI backbone and ascorbic acid as a biocompatible dopant of PANI. The antioxidant nature of CPs may reduce the serious repercussions of oxidative stress, produced during the ischemia-reperfusion (I/R) process following myocardial infarction. The polymerization parameters were considered as aniline (60 mM, 90 mM, and 120 mM), ascorbic acid concentrations ([aniline]:[ascorbic acid] = 3:0, 3:0.5, 3:1, 3:3), and polymerization time (1 h and 3 h). Mainly, the more aniline concentrations and polymerization time, the less sheet resistance was obtained. 1,1 diphenyl-2-picrylhydrazyl (DPPH) assay confirmed the dual antioxidant properties of prepared samples. The advantage of the employed in-situ polymerization was confirmed by the de-doping/re-doping process. Non-desirable groups were excluded based on their electrical conductivity, antioxidant properties, and biocompatibility. The remained groups protected H9c2 cells against oxidative stress and hypoxia conditions. Selected CPs reduced the intracellular reactive oxygen species content and mRNA level of caspase-3 while the Bcl-2 mRNA level was improved. Also, the selected cardiac patch could attenuate the hypertrophic impact of hydrogen peroxide on H9c2 cells. The in vivo results of the skin flap model confirmed the CP potency to attenuate the harmful impact of I/R.

Bifunctional Potential Structure Design Breaks Electrolyte Limitations of Zinc Ion Battery

AbstractAqueous zinc‐ion batteries (ZIBs) are safe and economical for grid applications. However, current ZIBs have limitations in terms of inferior capacity and low output voltage, which are hampered by the electrolyte applicability of the Zn2+ hosts. In this study, we propose a novel organic cathode design strategy with a bifunctional potential region. This polymeric Zn2+ host combines the conjugated polyaniline backbone to tune the molecular surface pH and [Fe(CN)6]3−/4− redox couple for high output voltage and capacity. The polyaniline doped with ferricyanide (PAF) electrode exhibits two forms of charge storage in ZIBs: proton‐assisted Zn2+ doping below 1.2 V (mechanism I), and [Fe(CN)6]3−/4− redox pair above 1.8 V (mechanism II). Density functional theory calculations and in situ pH experiments demonstrated that the H+ doping process of mechanism I forms a localized pH regulation on the molecular chain surface, providing a favorable reaction environment for mechanism II. The Zn‐polymer battery delivered an outstanding discharge capacity (405.2 mAh g−1) and high output voltage (1.8 V) in the Zn(CF3SO3)2 electrolyte. This study provides a new route for enhancing the structural stability of electrodes and overcoming the electrolyte limitations of ferricyanide in weakly acidic electrolytes.

Bifunctional Potential Structure Design Breaks Electrolyte Limitations of Zinc Ion Battery.

Aqueous zinc-ion batteries (ZIBs) are safe and economical for grid applications. However, current ZIBs have limitations in terms of inferior capacity and low output voltage, which are hampered by the electrolyte applicability of the Zn2+ hosts. In this study, we propose a novel organic cathode design strategy with a bifunctional potential region. This polymeric Zn2+ host combines the conjugated polyaniline backbone to tune the molecular surface pH and [Fe(CN)6]3-/4- redox couple for high output voltage and capacity. The polyaniline doped with ferricyanide (PAF) electrode exhibits two forms of charge storage in ZIBs: proton-assisted Zn2+ doping below 1.2 V (mechanism I), and [Fe(CN)6]3-/4- redox pair above 1.8 V (mechanism II). Density functional theory calculations and in situ pH experiments demonstrated that the H+ doping process of mechanism I forms a localized pH regulation on the molecular chain surface, providing a favorable reaction environment for mechanism II. The Zn-polymer battery delivered an outstanding discharge capacity (405.2 mAh g-1) and high output voltage (1.8 V) in the Zn(CF3SO3)2 electrolyte. This study provides a new route for enhancing the structural stability of electrodes and overcoming the electrolyte limitations of ferricyanide in weakly acidic electrolytes.

Interface engineering driven molybdenum disulfide coupled polyaniline functionalized carbon fabric with high mass loading anode for fiber lithium-ion batteries

Carbon fiber (CF) cloth presents a preeminent substrate for growing numerous active materials, emerging as a promising electrode design in fiber lithium-ion batteries (F-LiBs) for powering future wearable electronics. Nevertheless, the hydrophobic nature of CF affects the interaction between the active materials and CF, leading to inferior battery performance. Herein, we report a polyaniline (PANi) driven interface-engineering approach to address the recurring issue associated with CF. To demonstrate the concept, molybdenum disulfide (MoS2), a two-dimensional layered anode was grown on PANi-functionalized CF (MoS2/PANi/CF). The nitrogen functionalities of the PANi backbone enriched the surface functionality and facilitated the coupling adhesion between MoS2 and CF. This key feature influenced the charge transport kinetics across the MoS2/CF interface and preserved the structural integrity. More importantly, the strong coordination interaction between MoS2 and PANi improved the growth density of MoS2, resulting in high mass loading. Given these merits, the interfacially coupled MoS2/PANi/CF anode delivered a high specific capacity and enhanced rate and cycling performances. This study verifies the significance of the interface engineering approach, which can be extended to developing wide arrays of flexible electrodes for other wearable battery chemistries.

Enhancing the photoelectrochemical hydrogen evolution activity of polyaniline through small molecular acid doping to introduce polariton-enhanced active sites

Development of organic polymer photoelectrodes with high surface activity is the key to efficient water splitting for hydrogen production. Polyaniline (PANI) prepared under alkaline conditions has semiconducting properties, but high reaction rates are difficult to achieve due to its poor surface activity. In this study, electrochemical doping was used to introduce small molecular acids (2,3-hydroxybutanedioic acid (TA), 2-hydroxybutanedioic acid (MA), and succinic acid (SA)) containing different numbers of hydroxyl groups into the PANI backbone to form polarizers, dipolarizers and active sites. Density Functional Theory (DFT) shows that small molecular acids interact with the imine (=N-) structure of the PANI backbone via electron cloud stacking to form complex active sites. Meanwhile, the transition from polarons to dipolarons under light conditions increases the polarity of the PANI molecular chain, which further improves the photoelectrocatalytic performance. This study will bring new ideas for efficient photoelectrocatalysis based on organic polymers.

Synthesis and Characterization of a Novel Nanosized Polyaniline.

Polyaniline (PANI) is a conductive polymer easily converted into a conducting state. However, its limited mechanical properties have generated interest in fabricating PANI composites with other polymeric materials. In this study, a PANI-prevulcanized latex composite film was synthesized and fabricated in two phases following chronological steps. The first phase determined the following optimum parameters for synthesizing nanosized PANI, which were as follows: an initial molar ratio of 1, a stirring speed of 600 rpm, a synthesis temperature of 25 °C, purification via filtration, and washing using dopant acid, acetone, and distilled water. The use of a nonionic surfactant, Triton X-100, at 0.1% concentration favored PANI formation in a smaller particle size of approximately 600 nm and good dispersibility over seven days of observation compared to the use of anionic sodium dodecyl sulfate. Ultraviolet-visible spectroscopy (UV-Vis) showed that the PANI synthesized using a surfactant was in the emeraldine base form, as the washing process tends to decrease the doping level in the PANI backbone. Our scanning electron microscopy analysis showed that the optimized synthesis parameters produced colloidal PANI with an average particle size of 695 nm. This higher aspect ratio explained the higher conductivity of nanosized PANI compared to micron-sized PANI. Following the chronological steps to determine the optimal parameters produced a nanosized PANI powder. The nanosized PANI had higher conductivity than the micron-sized PANI because of its higher aspect ratio. When PANI is synthesized in smaller particle sizes, it has higher conductivity. Atomic force microscopy analysis showed that the current flow is higher across a 5 µm2 scanned area of nanosized PANI because it has a larger surface area. Thus, more sites for the current to flow through were present on the nanosized PANI particles.

Long-lived Photoacid-doped Conducting Composites Induce Photocurrent for Efficient Wound Healing.

Electrical stimulation is an effective strategy for facilitating wound healing. However, it is hindered by unwieldy electrical systems. In this study, we used a light-powered dressing based on long-lived photoacid generator (PAG)-doped polyaniline composites, which can generate a photocurrent under visible light irradiation to interact with the endogenous electric field and facilitate skin growth. Light-controlled proton binding and dissociation result in oxidation and reduction of the polyaniline backbone, inducing charge transfer to generate a photocurrent. Due to the rapid intramolecular photoreaction of PAG, a long-lived proton-induced localized acidic environment is formed, which protects the wound from microbial infection. In summary, we have introduced a simple and effective therapeutic strategy for light-powered and biocompatible wound dressings that show great potential for wound treatment. This article is protected by copyright. All rights reserved.

Synthesis of polyaniline-graphene oxide based ternary nanocomposite for supercapacitor application

This study focuses on the synthesis of Polyaniline (PANI), graphene oxide (GO), and their nanocomposites with metal oxides (MO) and hexagonal boron nitride (h-BN) for their application in the supercapacitor. In this study, PANI/GO, PANI/GO/TiO2, PANI/GO/MoS2 and PANI/GO/h-BN ternary nanocomposites were synthesized following a chemical oxidative polymerization method. The prepared nanocomposites were characterized by FTIR, XRD, TGA, SEM and electrochemical analysis. The electrochemical properties of the nanocomposites were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical polarization and impedance analysis. CV profile of the nanocomposite showed that incorporation of GO, MO and h-BN in the polyaniline backbone improved capacitance, energy density and power density significantly. Among the synthesized ternary nanocomposites, PANI/GO/h-BN showed highest capacitance of 946 F/g and high capacitance retention after 100 cycles of charging and discharging. Finally, a set of hybrid asymmetric supercapacitors were constructed using the synthesized nanocomposites as positive electrode and activated carbon as negative electrode. The device was assessed following the GCD method. The supercapacitor device with PANI/GO/h-BN nanocomposite as positive electrode exhibited higher specific capacitance of 351 F/g with high power density of 4500 W/kg, and it lit up a 5 mm LED for 243 min, indicating its superiority over other electrodes.

Facile preparation of water-dispersible carboxylated polyaniline

Polyaniline (PANI), containing carboxylic groups, was prepared by covalent modification of PANI base, using various amounts of thiolactic acid (TLA). It was found that using the excess of TLA, compared to the stoichiometric amount required for modification of emeraldine form of PANI, did not lead to increase of substitution degree. Elemental analysis showed that in all studied conditions ≈6.5 wt% of carboxylic groups were introduced into PANI backbone. Change of PANI chemical structure as a result of modification by TLA was studied by electronic, vibrational and photoelectron spectroscopy. It was shown that TLA is covalently bound to PANI without significant amount of free TLA and the initial PANI base also becomes partially protonated. Conductivity of PANI-TLA materials (≈5 ×10–7 S cm–1) increased by 4 orders of magnitude, compared to PANI base (5 ×10–11 S cm–1). Due to the presence of carboxylic groups, TLA-modified PANI is dispersible in alkaline aqueous medium, which can enable eco-friendly ways of PANI deposition for the applications in sensors and anticorrosive coatings.

Anthraquinone-2-sulfonic acid-loaded polyaniline nanostructures: Construction of symmetric supercapacitor electrodes thereof

Polyaniline (PANI) nanostructures were synthesized via an acid-free green route using redox-active, water-soluble 9,10-Anthraquinone-2-sulfonic acid sodium salt (AQSA). As a counter anion for the PANI backbone, the AQSA plays an important role in polyaniline (PANI) chain growth and as a morphology regulator. The AQSA doped PANI shows pronounced specific capacitance with effective cycling stability. As-synthesized nanotubular structures of PANI_AQSA (0.5, 1.0, and 1.5) with various concentration ratios of aniline to AQSA were achieved in appreciable yield. The intrinsic physico-chemical properties were analyzed using various physico-analytical techniques such as Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), powder X-ray diffraction analysis (XRD), Fourier Transmission Infrared spectroscopy (FT-IR), X-ray Photo Electron Spectroscopy (XPS), and Raman analysis. Nanotubular structures of PANI_AQSA were analyzed using FESEM studies. The electrochemical studies, galvanostatic charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS) were methodically investigated. PANI_AQSA_1.5 portrays enhanced specific capacitance of 440 Fg−1 at 1 Ag−1 (three-electrode system) in 1 M sulphuric acid electrolyte than its regular Cl− counter ion (276 Fg−1 at 1 Ag−1). The fabricated symmetric PANI_AQSA//PVA_H2SO4//PANI_AQSA supercapacitor showed a specific capacitance of 391 Fg−1 at 1 Ag−1 with 93 % capacitance retention for ~1000 cycles.

Unprecedented strong and reversible atomic orbital hybridization enables a highly stable Li-S battery.

The shuttle effect and excessive volume change of the sulfur cathode severely impede the industrial implementation of Li–S batteries. It is still highly challenging to find an efficient way to suppress the shuttle effect and volume expansion. Here, we report, for the first time, an innovative atomic orbital hybridization concept to construct the hierarchical hollow sandwiched sulfur nanospheres with double-polyaniline layers as the cathode material for large-scale high-performance Li–S batteries. This hierarchically 3D, cross-linked and stable sulfur–polyaniline backbone with interconnected disulfide bonds provides a new type and strong intrinsic chemical confinement of sulfur owing to the atomic orbital hybridization of Li 2s, S 3p, C 2p and N 2p. Crucially, such atomic orbital hybridization of sulfur sandwiched in the double sulfur–polyaniline network is highly reversible during the discharge/charge process and can very efficiently suppress the shuttle effect and volume expansion, contributing to a very high capacity of 1142 mAh g–1 and an excellent stabilized capacity of 886 mAh g–1 at 0.2 C after 500 cycles with a suppressed volume expansion and an unprecedented electrode integrity. This innovative atomic orbital hybridization concept can be extended to the preparation of other electrode materials to eliminate the shuttle effect and volume expansion in battery technologies. The present work also provides a commercially viable and up-scalable cathode material based on this strong and highly reversible atomic orbital hybridation for large-scale high-performance Li–S batteries.

Redox‐mediated proton transport of two‐dimensional polyaniline‐based nanochannels for fast capacitive performance

AbstractTwo‐dimensional (2D) materials are being increasingly exploited for ion transport and storage under nanoconfinement. Here we demonstrate distinct ion transport behavior upon potential‐induced redox reaction in 2D tungstate anion cross‐linked polyaniline (TALP) electrode. It is found that, in the neutral electrolyte, SO42− ion serves as the main charge carrier in 2D polyaniline backbone when the electrical double layer charging dominates. While in an acidic electrolyte, proton transport in TALP turns to be the dominant ion behavior that is associated with the proton‐promoting surface redox processes. Moreover, higher capacitance along with better capacitive retention at a high rate is also demonstrated for TALP electrode in acidic electrolyte compared with that in the neutral environment. The results show that 2D nanoionics can be manipulated by applying redox‐active materials to build the nanochannels that allow the regulation of surface charge and chemistry with potential‐specific redox reactions.

Synthesis and characterizations of Co–Zr doped Ni ferrite/PANI nanocomposites for photocatalytic methyl orange dye degradation

Co–Zr doped Ni ferrite substituted polyaniline (PANI) nanocomposites were prepared using polymerization reaction method. NiFeCo0.5Zr0.5O4 with 12.5%, 25%, 37.5% and 50% PANI (A1, A2, A3 and A4) were used to obtain better photocatalytic efficiency. XRD, UV/VIS, BET, and FESEM were employed to characterize the PANI/ferrite nanocomposites. The effect of reaction time and nanoparticle concentrations on the photocatalytic degradation were thoroughly evaluated. XRD analysis confirmed the phase of NiFeCo0·5Zr0·5O4ferrite, while FESEM analysis was performed to investigate the surface morphology of the nanocomposites. The crystallinity was increased with the Co–Zr doped Ni ferrite contents in the prepared nanocomposites. UV/VIS study was done to evaluate the optical properties. Shifting of peaks towards higher wave number in FTIR spectra evident the interactions between the polymer and nanoparticles. UV–Vis studies also confirm the interactions of dopant metals with polyaniline backbone chains. The surface area and porosity of the nanocomposites were concluded by BET and FESEM images. The kinetics studies of methyl orange were described by the Pseudo First-Order relation (best adjust R20.9947 for 50% w/w (A4)). The degradation efficiency was increased with the increase of Co–Zr ferrite contents which depicted the remarkable influences of nanoparticles in the nanocomposites. It is expected that the prepared PANI/NiFeCo0·5Zr0·5O4 nanocomposites are suitable photocatalyst for the removal of methyl orange in aqueous media.

Effect of low energy Li-negative ions irradiation on electrochemically synthesized Copper nanoflakes/Polyaniline nanofibers composite thin film

Multi cathode source of negative ions cesium sputtering unit is used for irradiation of 50 keV Li-negative ions with varying fluences from 5 × 1011 to 5 × 1014 ions/cm2 on polyaniline nanofibers and copper nanoflakes/polyaniline nanofibers composite thin films. The X-ray diffraction pattern of polyaniline nanofibers thin film shows the broad peak at 2θ≈25.36° which is the characteristic peak of polyaniline and the X-ray diffraction pattern of copper nanoflakes/polyaniline nanofibers show a prominent peak at 2θ≈50.66° which confirmed the presence of copper. Fourier transform infrared spectra confirmed the formation of polyaniline thin films with characteristics absorption band at 1438 cm−1 for a benzenoid ring of polyaniline backbone, which shifted slightly after irradiation. Polyaniline nanofibers and copper nanoflakes/polyaniline nanofibers composite thin films confirmed hydrophobic nature and the contact angle changes insignificantly after irradiation. Field emission scanning electron microscope images of polyaniline nanofibers and copper nanoflakes/polyaniline nanofibers composite thin films show the nanofibrous network of the diameters ranging from 50 nm to 60 nm and the copper nanoflakes get deposited uniformly on the polyaniline nanofibers. From the application point of view, this work might provide strong evidence to use negative ion irradiation for creating defects in polyaniline nanofibers and copper nanoflakes/polyaniline nanofibers composite thin films and it would attract wide attention towards their use in sensing, electronic devices, and energy storage device applications.

Phthalocyanine pendented polyaniline via amide linkage for an electrochemical sensing of H2O2

Cobalt phthalocyanines are known to be the better electrocatalyst for a wide range of organic, inorganic, and biomolecular analytes. The synthesis of electrocatalysts through phthalocyanine (Pc) functionalization involves a single-step reaction to a multi-step reaction. The functionalization of Pc catalyst with the conducting polymer involves either simple electronic interactions or direct covalent bonding. Here we are reporting covalently connected tetra carboxy cobalt phthalocyanine (TCCoPc) pendent via amide linking to the conducting polyaniline (PANI) backbone. The synthesized electrocatalyst is extensively utilized for the sensing of biologically active H2O2 on the surface of the catalyst modified glassy carbon electrode (GCE). The synthesized molecule was characterized by various spectroscopic techniques and the detailed electrochemical activity of the synthesized molecule for the sensing of H2O2 was investigated using linear sweep voltammetry and chronoamperometry techniques, by fabricating on the GCE. The superlative catalytic activity of the synthesized molecule is might be due to the synergetic effect of pendanted macrocyclic Pc molecule with the redox-active demeanor of central cobalt metal atom and anchoring of the metal-centered Pc through amide linking with the conducting PANI.

Synthesis of Phosphorus-Containing Polyanilines by Electrochemical Copolymerization.

In this study, the phosphonation of a polyaniline (PANI) backbone was achieved in an acid medium by electrochemical methods using aminophenylphosphonic (APPA) monomers. This was done through the electrochemical copolymerization of aniline with either 2- or 4-aminophenylphosphonic acid. Stable, electroactive polymers were obtained after the oxidation of the monomers up to 1.35 V (reversible hydrogen electrode, RHE). X-ray photoelectron spectroscopy (XPS) results revealed that the position of the phosphonic group in the aromatic ring of the monomer affected the amount of phosphorus incorporated into the copolymer. In addition, the redox transitions of the copolymers were examined by in situ Fourier-transform infrared (FTIR) spectroscopy, and it was concluded that their electroactive structures were analogous to those of PANI. From the APPA monomers it was possible to synthesize, in a controlled manner, polymeric materials with significant amounts of phosphorus in their structure through copolymerization with PANI.

Correlation between Nanoscale Elasticity, Semiconductivity, and Structural Order in Functionalized Polyaniline Thin Films.

The correlation between structural order, elasticity, and semiconductivity for butylthio-functionalized polyaniline (PANI-SBu) thin films was investigated using atomic force microscopy (AFM)-based techniques with X-ray diffraction (XRD) and scanning electron microscopy (SEM). After different stirring times, the thin films were cast from the solution of PANI-SBu in N-methyl-2-pyrrolidone that was continuously stirred at a constant rate of 150 rpm in an airtight round-bottom flask. According to the XRD and SEM results, the cross-sectional film structure evolved from being generally holey to highly lamellar with an increase in the stirring time. However, some new types of disordered structures began emerging beyond the optimal stirring time, possibly caused by the formation of disordered packing structures as contributed from the overoxidized polyaniline backbones during the additional stirring time. Moreover, according to the investigation results obtained using AFM-based techniques, the out-of-plane elastic moduli and charge mobilities of the PANI-SBu films were consistently smaller for disordered thin films and larger for structurally more ordered ones. The shear force resulting from the mechanical stirring of the PANI-SBu solution may gradually disentangle the polymer chains and thus help transform the individual polyaniline molecule from a coil-like chain conformation to a better extended rodlike chain conformation. Therefore, when cast into a film, the stretched polymer chains facilitate self-organization among the PANI-SBu backbones during the film formation process. Thus, an improved structural order in the film is attained. Our results demonstrate an unambiguous correlation between the structure order, elasticity, and conductivity in PANI-SBu thin films, which may have useful applications in conducting polymer-based flexible electronics.