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Covalent organic frameworks (COFs) possess extraordinary porosity, structural diversity, and good electrochemical performance, and have broad application prospects in the field of energy storage. However, the low conductivity of COFs limits its further development. In this paper, the electrochemical performance of triphenylamine-based COFs (TPA-COFs) was improved by compounding with highly conductive polyaniline (PANI) using solvothermal synthesis process. The highly conductive polyaniline fibers can act as conductive path in the composite to accelerate the charge transfer rate of TPA-COFs. The π-π interaction between TPA-COFs and PANI effectively decreases the agglomeration degree of PANI. The good dispersion of composite results in that the specific surface area of TPA-COFs/PANI-20 is high as 1233.9 m2 g−1, which provides rich diffusion channels for electrolyte ions. Moreover, the strong π-π structure in the composites ensures the stability of the material skeleton. Thus, TPA-COFs/PANI composite exhibits excellent rate characteristics and cycling stability.

Free-standing flexible supercapacitive electrodes have practical application for wearable energy storage devices. In this paper, graphene paper (GP), a flexible electrode substrate, was prepared by one-step reduction of graphene oxide (GO) using HI solution. GP can be used independently as a flexible electrode with specific capacitance of 227 F/g. In order to make up for the shortage of GP specific capacitance storage, polyaniline (PANI) with high specific capacitance and good electrical conductivity was selected to composite with GP by electrochemical polymerization approach. This method to fabricate electrode material by direct electrochemical polymerization avoids the use of conductive binder and organic solvent. Owing to the specific capacitance contribution of PANI and GP, the PANI/GP composites exhibit higher specific capacitance when the polymerization time is 30 s and the polymerization voltage is 0.8 V. At 1 A/g current density, the specific capacitance of composite is up to 759 F/g, which is 3.34 times of neat GP.

Composite supercapacitive materials can combine two different kinds of electrode materials with different energy storage mechanisms, as well as present enhanced supercapacitive performance. In this paper, a reduced graphene oxide aerogel (GA) was prepared with an adjustable pore structure and used as a matrix for loading of secondary active material (MnO2) through an electrochemical deposition method. The influences of the deposition time and deposition voltage on the electrochemical behaviors and specific capacitances of MnO2/GA composites were studied. The unique three-dimensional porous structure of GA can act as a good matrix for MnO2. The results show that when the deposition time is 30 s and deposition voltage is 1.0 V, the MnO2/GA composite has the highest specific capacitance of 664 F/g at a current density of 1 A/g. Compared with neat GA, the specific capacitance of the MnO2/GA composite is enhanced by 190%, which can be assigned to the co-contribution of two kinds of active materials, a facile ion diffusion path through the porous structure, and good electron conductivity of the GA.

A Poly (3, 4-dioxyethylthiophene)–Carbon Nanotubes (PEDOT–CNT) composite electrochromic material, connected by interfacial covalent bonds, was successfully synthesized by electrochemical copolymerization of 3, 4-dioxyethylthiophene with thiophene-2-methylamine functionalized CNT. The molecular and aggregate structures of PEDOT–CNT were investigated by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The electrochemical behavior and electrochromic properties of PEDOT–CNT were measured by CV (cyclic voltammetry), UV–Vis (ultraviolet visible spectroscopy) and EIS (electrochemical impedance spectroscopy). The test results show that the electrochromic performance of PEDOT–CNT is better than that of neat PEDOT. As the percentage of carbon nanotubes increases, the contrast and response speed of the composites increase accordingly. The PEDOT film has a contrast under square-wave potential of 0.54, a coloring time of 6.42 s, and a fading time of 2.54 s. Compared with PEDOT, the contrasts of PEDOT–CNT-3%, PEDOT–CNT-5% and PEDOT–CNT-7% are increased by 31%, 33%, and 89%, respectively. The response speeds of PEDOT–CNT-5% increase to coloring time of 3.51 s and fading time of 1.37 s.

Polyaniline nanotubes (PANI-T) and graphene oxide (GO) have been compounded by a postcomposition method with the assistance of electrostatic adsorption. Using this so-called postcomposition method, both the electric double-layer capacitance of the GO and the pseudocapacitance of the conducting polymer can be utilized. PANI-T prepared by a rapid mixing method was positively charged by pretreatment with (3-aminopropyl)triethoxysilane (APTES). PANI/GO composites were obtained by mixing the positively charged PANI-T and negatively charge GO with the assistance of electrostatic attraction. Charge–discharge measurements in 1 mol L−1 H2SO4 aqueous electrolyte revealed that the specific capacitance of PANI-T/GO-10% could reach 1220 F g−1 at a current density of 0.5 A g−1, being much higher than the value of 648 F g−1 for PANI-T. After 500 cycles of charge–discharge testing, the composite retained 97% of its capacitance. These enhanced supercapacitive properties can be attributed to the two types of energy storage mechanism and the electrostatic interaction between GO and PANI-T. Preparation of such PANI-T/GO composite electrode materials by electrostatic adsorption thus provides an efficient approach for improvement of the supercapacitive properties of conducting polymers or metal oxides.

Multiferroic YFeO3 nanofibers were prepared by electrospinning. The as-prepared nanofibers were characterized by XRD, TG-DTA, SEM and Raman spectrum. The magnetic property and photocatalytic activi...

In this paper, water-dispersible and covalently bonded polyaniline-carbon nanostructures, including polyaniline-reduced graphene oxide (PANI-rGO), polyaniline-single-walled carbon nanotubes (PANI-SWCNTs), and polyaniline-reduced graphene oxide/single-walled carbon nanotube (PANI-rGO/SWCNTs) nanocomposites, were synthesized by grafting PANI onto p-phenylenediamine (PPD)-functionalized graphene oxide (GO) or single-walled carbon nanotubes (SWCNTs) using polystyrene sulfonate (PSS) as a macromolecular dopant agent. The structures and morphologies of the PANI, PANI-rGO, PANI-SWCNTs, and PANI-rGO/SWCNTs nanocomposites were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The cyclic voltammetry and UV–vis spectra were performed on an electrochemical workstation and a UV–vis spectrometer, respectively. The results show that the electrochromic and electrochemical properties of nanocomposites can benefit from the high conductivity of SWCNTs and the abundant active sites of rGO. When SWCNTs and rGO work together, their respective shortcomings are overcome, allowing the nanocomposite to exhibit the best electrochemical and electrochromic properties. The optical contrast increased from 0.38 for PANI to 0.52 for PANI-rGO/SWCNTs. The coloring and bleaching times decreased from 2.59 s and 2.39 s, respectively, for PANI to 1.33 and 0.78 s, respectively, for PANI-rGO/SWCNTs. The charge transfer resistance (Rct) decreased from 135 Ω for PANI to 30 Ω for PANI-rGO/SWCNTs. The synergistic effect of PANI, rGO, and SWCNTs can significantly improve the electrochromic ability of PANI. Electrochromic properties of covalently bonded polyaniline-reduced graphene oxide/single walled carbon nanotubes nanocomposites. A high performance electrochromic material was prepared using polyaniline (PANI) and two different dimensional carbon nanostructures, single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) as the components. The covalent bond was introduced to interface between PANI and two carbon nanostructures to form a three-dimensional conductive network. Owing to the high electron conduction through directly connected covalent bond and loose molecular chain aggregation brought by two various dimensional carbon nanostructure, PANI-rGO/SWCNTs nanocomposites exhibit superior electrochemical and electrochromic properties (high optical contrast and short switching time) compared with PANI.

In this study, polyaniline (PANI) nanostructures with different morphologies (nanofibers, nanotubes, and nanospheres) were obtained via interfacial polymerization, rapid mixing reaction, and hydrothermal method. The influences of the synthesis methods on the morphologies and supercapacitive properties of PANI nanostructures were investigated. The chemical structures of materials were characterized by Fourier-transform infrared and Raman spectroscopies. Scanning electron microscopy and transmission electron microscopy images were used to explore the morphologies of PANI nanostructures. N2 adsorption–desorption isotherm, cyclic voltammetry, charge–discharge test, and electrochemical impedance spectroscopy were used to characterize the pore distribution, electrochemical, and supercapacitive properties of PANI nanostructures. The results show that PANI nanotubes (PANI-T) exhibit the best electrochemical performances among three kinds of PANI nanostructures. The PANI-T exhibits high specific capacitances of 648 and 290 F g−1 at current densities of 0.5 and 10 A g−1, respectively, indicating its good supercapacitive property and rate capability. The enhanced electrochemical and supercapacitive performances can be attributed to its hollow nanotube structure.

In view of the poor electronic conductivity and inferior structural stability, the direct application of Metal-Organic Frameworks (MOFs) as an electrode material is limited. Herein, the carboxylated multi-wall carbon nanotubes (MWCNT) are utilized as a substrate for the in-situ growth of bimetallic NiCo-based MOFs (NiCo-MOF). The flower-string-like NiCo-MOF/MWCNT composites are successfully synthesized using 4, 4′-biphenyldicarboxylic acid (BPDC) as a ligand via a simple solvothermal approach. In the composites, MWCNT is wrapped with 2D NiCo-MOF nanosheets through some bonds or affinity between MWCNT and NiCo-MOF. Meanwhile, the MWCNT presence does not affect the formation of the NiCo-MOF crystals. Compared with the hydrangea-like NiCo-MOF microspheres, the flower-string-like composite structures are more loosely assembled by NiCo-MOF nanosheets. Owing to the guiding effect of MWCNT on the NiCo-MOF growth, many well-dispersed flower-string-like structures can be achieved by adjusting MWCNT dosages. Due to the unique hierarchical structure and good synergistic effect, the NiCo-MOF/MWCNT composites exhibit excellent capacitance performances. The optimal composites demonstrate a large specific capacitance of 1010 F g−1 at 0.5 A g−1, a good rate capability (760 F g−1 even at 10 A g−1), a good cycling stability and reversibility with the capacitance retention of 828 F g−1 (100% of the initial capacitance) and coulombic efficiency of approximate 98% at 5 A g−1 after 3000 cycles, a low internal resistance and charge transfer resistance. The asymmetric supercapacitor assembled by NiCo-MOF/MWCNT composites as electrode materials has high energy density even at high power density, good rate capability, excellent cycling stability and reversibility. Hence, the as-synthesized NiCo-MOF/MWCNT composites are a promising high-performance electrode material for supercapacitors.

In this article, polyaniline nanofibers (PANI-NF)/manganese dioxide composites (PANI/MnO2) were synthesized through an interfacial polymerization approach. The PANI-NF and MnO2 were obtained by in situ oxidation of aniline by potassium permanganate and in situ reduction of potassium permanganate by aniline, respectively. During the interfacial polymerization, the monomer aniline can only be oxidized to PANI after it diffuses into the water phase. This diffusion-control feeding process of the monomer results in nanofiber structure. The morphologies and crystal structures of the prepared PANI/MnO2 composites were measured by scanning electron microscopy and x-ray diffraction. The supercapacitive behaviours of these composites were analysed by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) tests. The CV and GCD tests indicate that the PANI/MnO2 composites possess better electrochemical activity and higher capacitive properties compared to neat PANI nanofibers. The specific capacitance of PANI/MnO2 composites and PANI-NF are 751 F g−1 and 180 F g−1 at 0.2 A g−1 in Na2SO4 solution, respectively. We believe that the enhanced capacitive properties are related to the special nanostructure and strong interaction between PANI and MnO2 that resulted from the interfacial synthesis method.

Polyaniline nanowires (PANI NWs) were synthesized under different temperatures through a facile hydrothermal method and used as electrodes for high-performance pseudocapacitor. The resulting samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron micrographs, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Electrochemical properties of these PANI electrodes are studied by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy in 0.5M H2SO4 aqueous solution. The highest specific capacitance is obtained on the PANI NWs synthesized under 80°C (PANI-80) with 540.0 F g−1 at current density of 0.5 A g−1 accompanied with 82% specific capacitance retention after 1000 charge discharge cycles at 5 A g−1 current density.

In this article, polyaniline nanofibers/reduced graphene oxide (PANI-NFs/rGO) nanocomposites were prepared by a one-pot hydrothermal method. Under the condition of high temperature and high pressure, graphene oxide (GO) was reduced to rGO and aniline was in-situ polymerized to form PANI-NFs using ammonium persulfate as oxidant. The morphologies and structures of PANI-NFs/rGO nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and Raman analysis. The results show that PANI-NFs uniformly grow on the surfaces of rGO sheets, which can act as spacers to prevent the aggregation of rGO. Combining with FTIR and Raman analysis, it can be concluded that PANI-NFs/rGO nanocomposites are successfully prepared. The electrochemical performances of PANI-NFs/rGO nanocomposites were tested by cyclic voltammetry and galvanostatic charge–discharge. The PANI-NFs/rGO nanocomposites exhibit superior electrochemical performances compared to the PANI-NFs. With 10 wt% of GO loaded, the PANI-NFs/rGO nanocomposite exhibits highest specific capacitance of 942 F g−1 at a current density of 1 A g−1. The PANI-NFs/rGO nanocomposites also demonstrate good rate capacity and high cycling stability under the high discharging current density (10 A g−1), the specific capacitance can still reach to 680 F g−1. After 1000 charge–discharge cycling at a current density of 5 A g−1, 78% of specific capacitance can be retained. The enhanced capacitive performances can be attributed to the facile electron conduction pathway brought by the even distribution of highly conductive rGO nanosheets.

NiCo-based bimetal-organic frameworks (NiCo-MOF) are synthesized via a hydrothermal approach, using 4,4′-biphenyldicarboxylic acid (BPDC) as a ligand. Structural characterizations find that NiCo-MOF is composed of one-dimensional micro-nanorods and regular three-dimensional cuboids assembled by one-dimensional micro-nanorods，possessing a good crystalline structure, in which nickel and cobalt ions have been coordinated to the BPDC ligands. Moreover, NiCo-MOF can be stable below 300 °C in air. The electrochemical measurements show that GCD activation at a high current density can significantly increase the capacity of NiCo-MOF due to decreasing the charge-transfer resistance and ion diffusion impendence. The specific capacitance of NiCo-MOF reaches 990.7 F/g from 156.5 F/g at 1 A/g, and the coulombic efficiency increases to 98.0% from 77.6% after the CV-GCD activation. Activated NiCo-MOF exhibits prominent pseudocapacitive behaviors, high specific capacitances at different current densities and a good cycling stability after 1000 cycles. The capacity of NiCo-MOF is up to 405.0 F/g when the current density increases to 20 A/g, and remains 553.2 F/g at 1 A/g after 3000 cycles. Compared with monometallic Ni-MOF and Co-MOF, bimetallic NiCo-MOF possesses a much higher capacity at different current densities due to the lower intrinsic resistance, charge-transfer resistance and ion diffusion impendence.

In this article, we reported a biomass carbon/MnO2 nanocomposite electrode material prepared by a hydrothermal method. Sugarcane bagasse and KOH were the carbon source and activation agent, respectively. The obtained sugarcane bagasse carbon is rich in pore structure, so it can act as the host for MnO2. The biomass carbon/MnO2 nanocomposite electrode was prepared by a hydrothermal method. The morphologies of materials were observed by scanning electron microscopy. Raman spectra and x-ray diffraction were utilized to characterize the molecular and crystal structures of samples, respectively. The electrochemical and capacitive performances of materials were tested by electrochemical workstation. By calculation, the specific capacitance of sugarcane bagasse carbon, MnO2 and composite electrode are 280 F g−1, 163 F g−1 and 359 F g−1, respectively. Compared with pure sugarcane bagasse carbon and MnO2, the specific capacitance of the composite increases by 28% and 120%, respectively. After 2000 cycles of charge and discharge, the capacitance retention of the composite is 94%, which is higher than 91% of sugarcane bagasse carbon and 45% of MnO2.

A novel ferrocene-containing hybrid electrochromic material was synthesized via copolymerization of aniline with p-phenylenediamine functionalized acetyl ferrocene in the presence of poly (styrene sulfonate) dopant in an aqueous medium, and neat polyaniline (PANI) was prepared for comparison. The polymerization characteristics and the structure of the copolymer were systematically studied by Fourier-transform infrared, meanwhile, their electrochromic properties and electrochemical behaviors were tested by UV–vis spectra, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). It was found that the strong covalent bond and large conjugated system between PANI and ferrocene enhance the electron transfer rate and electron delocalization in the ferrocene-polyaniline (Fc-PANI) hybrid. In particular, the electrochromic device with Fc-PANI as the active layer shows significant enhancement in optical contrast over the PANI-based device.

In this study, we fabricated hexagonal YFeO3 films on Si(100) and Si(111) substrates by a sol-gel method, and investigated the effect of substrate orientation on the structural, ferroelectric and piezoelectric properties of the YFeO3 films. Grazing incidence X-ray diffraction reveals that the YFeO3 films on Si(100) and Si(111) have slight preferred-orientation in (110) and (004) direction, respectively. Both films possess granular microstructure with good crystallization, as well as low surface roughness. The (004)-oriented film has higher density than the (110)-oriented film, resulting in lower leakage current. The two films show weak ferroelectric properties and different domain structures. Local amplitude and phase response loops manifest that the film on Si(111) possesses larger phase change and coercive field. While influenced by polarization rotation towards the applied field direction, larger effective piezoelectric coefficient d33 of 67 pm/V has been found in the film on Si(100). These findings suggest that preferred orientation can account for the physical properties of multiferroic YFeO3 films.

The molecular architecture of conducting polymers has a significant impact on their conjugated structure and electrochemical properties. We have investigated the influence of star-shaped structure on the electrochemical and electrochromic properties of polyaniline (PANI). Star-shaped PANI (SPANI) was prepared by copolymerization of aniline with triphenylamine (TPA) using an emulsion polymerization method. With addition of less than 4.0 mol.% TPA, the resulting SPANI exhibited good solubility in xylene with dodecylbenzenesulfonic acid (DBSA) as doping acid. The structure and thermal stability of the SPANI were characterized using Fourier-transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis, and the electrochemical behavior was analyzed by cyclic voltammetry (CV). The electrochromic properties of SPANI were tested using an electrochemical workstation combined with an ultraviolet–visible (UV–Vis) spectrometer. The results show that, with increasing TPA loading, the thermal stability of SPANI increased. With addition of 4.0 mol.% TPA, the weight loss of SPANI was 36.9% at 700°C, much lower than the value of 71.2% for PANI at the same temperature. The low oxidation potential and large enclosed area of the CV curves indicate that SPANI possesses higher electrochemical activity than PANI. Enhanced electrochromic properties including higher optical contrast and better electrochromic stability of SPANI were also obtained. SPANI with 1.6 mol.% TPA loading exhibited the highest optical contrast of 0.71, higher than the values of 0.58 for PANI, 0.66 for SPANI-0.4%, or 0.63 for SPANI-4.0%. Overdosing of TPA resulted in slow switching speed due to slow ion transport in short branched chains of star-shaped PANI electrochromic material. Long-term stability testing confirmed that all the SPANI-based devices exhibited better stability than the PANI-based device.

In this paper, we demonstrate a simple approach to improve the electrochromic performances of polyaniline (PANI) by incorporating PANI nanofibers (PANI-NFs) synthesized by interfacial polymerization into water-soluble PANI:poly(styrene sulfonate) (PANI:PSS). The one-dimensional PANI-NFs endow spin-coated PANI film high electrochemical activities and electrochromic properties. The structures and morphologies of PANI-NFs were characterized by FTIR spectroscopy and SEM observation. The electrochemical behaviors of PANI/PANI-NFs composites were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochromic properties of composites were tested using electrochemical working station combining a UV-Vis spectrometer. The results show that the PANI-NFs with even diameter of ~ 30 nm can be synthesized easily using interfacial polymerization method. With the increasing of feeding amount of PANI-NFs, the oxidation peaks of CV curves shift to low potential direction, indicating enhanced electrochemical activities. The electrochromic test confirms that the PANI/PANI-NFs composites films have higher electrochromic contrast of 0.67 as comparison to 0.49 of PANI:PSS film. The PANI/PANI-NFs also exhibit excellent electrochromic stability. After 2000 cycles switching, only less than 4% contrast decay is observed. The enhanced electrochromic properties can be attributed to the small charge-transfer resistance and facile ion diffusion process brought by PANI-NFs. The EIS tests exhibit that with incorporating of highly conductive PANI-NFs, the PANI/PANI-NFs composites possess relatively lower charge-transfer resistance of 76 Ω as comparison to 94 Ω of neat PANI:PSS.

We report a facile strategy to synthesize WO 3 -RGO composite by intimately coating WO 3 nanoflower with RGO via an electrostatic attraction between positive charge modified WO 3 and negatively charged GO. The WO 3 -RGO composite showed higher specific capacitance (495 F g −1 at a current density of 1 A g −1 ) compared with pure WO 3 (127 F g −1 ) in 0.5 M H 2 SO 4 aqueous electrolyte. In addition, the WO 3 -RGO composite electrode showed excellent cyclic stability of 87.5% even after 1000 cycles. The enhancement in specific capacitance and excellent cyclic stability of the composite electrode is mainly due to sufficient interfacial contact as well as synergetic effect of pure WO 3 and graphene. The experimental results demonstrated that WO 3 -RGO composite is a promising electrode material for high-performance supercapacitors.

In this paper, the covalently bonded polyaniline (PANI) nanofiber/multi-walled carbon nanotubes (MWCNT) composites were synthesized via interfacial polymerization of aniline with para-phenylenediamine functionalized MWCNT at the interface of oil/water system. Owing to the diffusion-controlled growth process of PANI, PANI with uniform fiber structure were obtained. The morphology analysis showed that the diameter of PANI nanofiber decreased with the increasing of MWCNT loading amount. Impedance analysis showed that the charge-transfer resistances of the composites were reduced also with the increasing of MWCNT loading amount. The decreasing of charge-transfer resistances and change of morphology resulted in enhanced capacitive properties. Electrochemical tests showed that the specific capacitance of PANI, PANI/MWCNT-10% and PANI/MWCNT-20% were 405, 641 and 764 F·g-1, respectively. As comparison with pure PANI nanofiber, the specific capacitance of the composites increased by 58% and 88.6%, respectively.

As one of the important factors which affect the properties and applications of conducting polymers, the electrical conductivity of a poly(3,4-ethylenedoxy-thiophene)/ poly(styrene sulfonate) (PEDOT: PSS) blend was adjusted by using various amount of an organic solvent (N,N-dimethyl formamide, DMF) as an additive. The conductivities of PEDOT: PSS thin films can be increased dramatically, from 1.0 S to 32.1 S cm−1, with a 2/1 volume ratio of PEDOT: PSS/DMF loading after totally removing the organic solvent by annealing the film at 80° for 48 h in a vacuum oven. The optical contrasts of transmissive and reflective devices assembled using DMF-modified PEDOT: PSS as active layers exhibited a close relationship with the conductivity of PEDOT: PSS. Interestingly, high conductivity of PEDOT: PSS enhanced the contrast of a transmissive device, while high conductivity of PEDOT: PSS decreased the contrasts of a reflective device. The underlying reason is related to the different electrochromic mechanisms of these t...

High conductivity, good stability, and high transmittance in the visible region are the three essential requirements for the polymer electrodes used in the optoelectronic devices. It was found that with addition of diols, such as ethylene glycol, diethylene glycol, or poly(ethylene glycol) (PEG), to the poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) emulsion before spin-coating could increase dramatically the conductivities of the resultant PEDOT:PSS thin films from 1 to 90 S cm−1 while maintain the optical transparency of the modified thin films. With up to −2.4 V potential applied, the PEDOT:PSS with PEG 200 additive does not show obvious color change, indicating its good electrochemical stability as polymer electrode. Detailed studies on the structures and morphologies of these modified PEDOT:PSS thin films, in comparison to that of PEDOT:PSS without additives were carried out using AFM, Raman, and FTIR to investigate the underlying mechanisms.

In this Article, we report the layer-by-layer (LbL) assembly and electrochromic properties of polyaniline-tethered cubic polyhedral oligomeric silsesquioxane (POSS-PANI)/sulfonated polyaniline (SPANI) multilayer thin films. The interaction between POSS-PANI and SPANI is characterized using X-ray photoelectron spectroscopy (XPS), ultraviolet−visible-near-infrared spectroscopy, and four-point probe conductivity. We show that the inclusion of SPANI during LbL assembly effectively dopes the underlying POSS-PANI layer and extends the conjugation length, as evidenced by probing the surface layers with XPS. We also demonstrate that the POSS-PANI/SPANI multilayer films have more electroactive units, lower band gap energies, and higher electrical conductivity values compared to those of POSS-PANI/poly(2-acrylamido-methane-2-propanesulfonic acid) (PAMPS) and spin-coated SPANI films. Under constant applied potentials, a 50 bilayer film of POSS-PANI/SPANI, (POSS-PANI/SPANI)50, shows significant enhancement in optical...

In this article, we report the synthesis, structures, morphologies, and electrochromic properties of covalently bonded polyaniline (PANI)−TiO2 hybrids. The hybrids were synthesized via a sol−gel process, followed by oxidative polymerization, using a bifunctional compound to bridge the two phases. In comparison with PANI, the hybrids show significant enhancement in optical contrast and coloration efficiency. Furthermore, when covalently bonded to PANI, the TiO2 nanodomains can act as electron acceptors, reducing the oxidation potential and band gap of PANI, and improving the long-term electrochromic stability.

Copolymerization of aniline with octa(aminophenyl) silsesquioxane (OAPS) was performed, which resulted in polyaniline-tethered, polyhedral oligomeric silsesquioxane (POSS-PANI), with star-like molecular geometry. The spectro-electrochemical studies show that the electrochromic contrast of POSS-PANI is much higher than that of polyaniline (PANI). The great improvement can be attributed to the more accessible doping sites and the facile ion movement during the redox switching, brought by the loose packing of the PANI chains. This was evidenced by a drastic increase in ionic conductivity, a decrease in the electrical conductivity, and a decrease in the crystallinity and crystal size, with the increase of the OAPS concentration in the POSS-PANI.

In this article, highly ordered PANI/TiO2 bilayer microtubes were prepared with two-step method. Firstly, anodic aluminum oxide (AAO) membrane with regular channel structure was chosen as the template, the PANI microtubes were synthesized in the channels of template by in situ polymerization. Secondly, the TiO2 microtubes were synthesized with sol–gel method in the channels of PANI microtubes. The structure and morphology of PANI/TiO2 bilayer microtubes were characterized by SEM, energy dispersive spectroscopy (EDS), TEM, and UV–vis. The results showed that the bilayer microtubes were successfully synthesized in the microchannels of template, the diameter and length of microtubes were closed to the pore diameter and thickness of AAO template, respectively, the arrangement of bilayer microtubes was very regular and uniform, also, a bilayer structure was found. UV–vis spectra confirmed that the photocatalysis property of PANI/TiO2 bilayer microtubes in sunlight was better than that of TiO2 microtubes, due to the existence of sensitizer, PANI.

The poly(2,5-dimethoxyaniline) (PDMA) were synthesized through interfacial polymerization method using three various organic solvent/water reaction systems. As comparison with conventional chemical polymerized PDMA, the interfacial polymerization can produce uniform nanoparticular PDMA, especially for using high density (higher than water) solvent as organic phase. The capacitive performances of interfacial polymerized PDMA can be benefited from its uniform morphologies and loose packing structure. The specific capacitance of interfacial polymerized PDMA using carbon tetrachloride is 194 Fg−1 at current density of 50 mA cm−2, which has 59% enhancement over 122 Fg−1 of conventional PDMA at the same current density. The energy density of interfacial polymerized PDMA is 39 Wh kg−1 at current density of 5 mA cm−2 and the power density is 28,421 W kg−1 at current density of 50 mA cm−2. The energy density has improvement in different extent as comparison with that of conventional PDMA. The enhanced capacitive performances can be attributed to the increased ionic conductivity induced by the loose molecular packing structure and uniform morphology produced by the interfacial polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40666.

A reverse-barrier technique is used to enable the treatment of electrospun poly(vinylidene fluoride) nanofibrous membranes with supercritical carbon dioxide. The treatment induces the formation of nanopores and extended-chain β crystallites of small lateral dimensions in the nanofibers. It also creates interfiber junctions, resulting in a remarkable improvement in mechanical properties of the membranes. The treated membranes are able to retain their shape very well after loading with an ionic liquid (IL). The ionic conductivity of the IL-loaded membrane is very close to that of the neat IL.

Polymer electrolyte is an important component in many multilayer devices such as batteries, fuel cells, and electrochromic devices. The effects of polymer electrolyte solidification on the ionic movement and device performance are presented based on near-infrared (IR) (860-2500 nm) electrochromic (EC) devices using the conducting polymer polyaniline. EC devices using electrolyte with polar polymer host of P(VDF-TrFE) show stable and reversible light modulation up to 65% in gel state and 30% in solid state. This is significantly improved when compared to devices with solidified nonpolar polymer host which retains less than 10% light modulation. Electrochemical impedance combined with in situ light modulation measurement identifies various key characteristics exerted by the electrolyte states on device performance. Gel-state devices are affected by the amount of dissociated ions while ionic movement in the electrolyte bulk and through the electrolyte/EC material interface dictates the light modulation in semisolid devices. For solid-state devices, electronic leakage, ionic dissociation, and interaction with electrochrome molecules have been found to limit the operation.

Template synthesis technique was employed to prepare magnetic polyaniline (PANI)/Fe3O4 composite microtubes using anodic aluminum oxide (AAO) membrane as template. Magnetic microtubes were obtained through in situ polymerization of aniline in the presence of Fe3O4 nanoparticles in the microchannels of template. A tubular structure was formed once when aniline was preferentially adsorbed and polymerized on the surface of channels wall. Electron microscope images demonstrated that the shape and size of guest (PANI/Fe3O4 composite microtubes) were strictly depended on those of the host (template channels). Magnetic force microscopy images showed that the PANI/Fe3O4 composite microtubes possessed reasonable magnetism and the magnetism distribution of microtubes was regular as distribution of template channels. Moreover, the magnetic response and oriented arrangement of PANI/Fe3O4 microtubes were fulfilled in the magnetic field. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009