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Abstract: This paper describes the effects of polyimide (PI) structure on electrical conductivity of blends of dodecylbenzene sulfonic acid-doped polyaniline (PANI-DBSA) and PI, as well as its thermal degradation behavior. Four types of PIs with different molecular architecture were synthesized and subsequently solution blended with PANI-DBSA. Of the four types of PIs, 4-4′-diaminodiphenyl sulfone (DADPS)-based PI provides the highest conductivity to the blends. It is attributed to the rigid nature of DADPS, which may induce more extended conformation of PANI chains, and hence result in a more ordered structure. The conductivity of the blends has significant higher thermal stability than that of PANI-DBSA. The thermal stability is, however, independent on the polyimide structure. TGA studies show that the PI matrix may have hindered the thermo-oxidative degradation and evaporation of the dopants and thus slowed down the process of thermal degradation of the conductivity. [Copyright &y& Elsevier]

This paper describes the effect of molecular weight of dopants on thermal degradation behaviour of electrical conductivity of polyacrylic acid (PAA) doped polyaniline (PANI). Two PAA with weight-average molecular weight (Mw) of 5000 and 250,000, respectively, were used as dopants to synthesise PANI–PAA complexes by in situ oxidative polymerisation. PANI doped with the low Mw PAA has lower electrical conductivity, which is attributed to its smaller size of crystal islands due to the end group effect. When annealed at 180 °C, within a period of 2 h the conductivity of PANI doped with the high Mw PAA decreases continuously with the annealing time following σ=σ0 exp[−(ta/τ)1/2] law, while the one doped with the low Mw PAA obeys this law only within 1 h of annealing. This indicates that the decrease of conducting island size is responsible for the thermal degradation of the conductivity of the complexes in a certain period and the length of this period depends on Mw of the dopants. TGA study shows that at 180 °C weight loss rates of the low and high Mw PAA doped PANI are about the same, which implies that the faster reduction of the conductivity in the low Mw PAA doped PANI is mainly due to its smaller initial crystal size. FT-IR study shows that annealing leads to de-doping, but it is less pronounced in the high Mw PAA doped PANI. [Copyright &y& Elsevier]

Polyaniline (PANI) doped with dodecylbenzene sulphonic acid (DBSA) and methylbenzene sulphonic acid (MBSA) were used as model compounds to investigate thermal degradation mechanisms of electrical conductivity of PANI salts. The effects of high temperature annealing on the conductivity, thermal stability and morphology of the doped PANI were studied. Within a period of 2 h, the conductivity of the two PANI salts decreases continuously with the annealing time. The conductivity reduction also increases significantly with the annealing temperature. Both polymers show significant weight loss during the annealing, especially at 200 °C. The weight loss of PANI–MBSA is more pronounced than that of PANI–DBSA, while the conductivity reduction shows an opposite trend. Scanning electronic microscopy (SEM) study reveals a significant morphology change caused by the annealing. Fourier transformed infrared (FT-IR) results indicate that some dopants are converted to free acids due to the annealing. It is, therefore, suggested that in addition to cross-linking of PANI and evaporation and degradation of the dopants, the segregation of the dopants from the polymers is also an important mechanism responsible for the conductivity degradation observed. [Copyright &y& Elsevier]

Abstract: A high-contrast complementary electrochromic device based on polyaniline (PANI) tethered polyhedral oligomeric silsesquioxane (POSS) (POSS-PANI) and poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonic acid) (PEDOT:PSS) is assembled. The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure, POSS-PANI gives rise to a significantly higher electrochromic contrast, coloration efficiency and faster switching speed than PANI. Despite its high contrast, the combination of POSS-PANI with PEDOT:PSS still shows synergy in terms of contrast enhancement, which can be attributed to the additional driving force for the diffusion of dopants into PEDOT:PSS provided by the dedoping of POSS-PANI. [Copyright &y& Elsevier]

Abstract In this article, we report a thin film of polyaniline (PANI)-grafted single-walled/double-walled carbon nanotubes (CNTs) on polyethylene terephthalate (PET) as a transparent electrode for highly bendable electrochromic films. Our results show that the high conductivity of the PANI-CNT/PET electrode brought by its conductive CNT network, as well as the strong conjugation between CNTs and PANI, can be well retained even after 9000 cycles of bending with a bending radius of 0.6 cm, which is superior to that of the most widely used transparent electrode, indium tin oxide (ITO) on PET. By electrodeposition of PANI on the PANI-CNT/PET electrode, the overall electrochromic performance of the PANI-deposited PANI-CNT/PET (PANI/PANI-CNT/PET) is comparable to its PANI/ITO/PET counterpart, whereas after 100 cycles of bending, PANI/PANI-CNT/PET can much better retain its initial electrochromic performance than PANI/ITO/PET. The mechanism for the enhanced bendability is studied via impedance analysis. It shows that the enhancement is mainly due to the robust interface between the PANI-based electrode and active layer. The findings provide a new avenue for rational design of highly bendable electrodes for flexible electrochromic devices. Graphical abstract Image 1 Highlights • Polyaniline-grafted carbon nanotubes (PANI-CNT) as a transparent flexible electrode. • The electrode retains its conductivity after 9000 cycles of bending. • PANI can be electrodeposited on PANI-CNT to form PANI/PANI-CNT electrochromic film. • Superior bendability of PANI/PANI-CNT than its PANI/indium tin oxide counterpart. • The strong interface between the active layer and electrode is the key mechanism. [ABSTRACT FROM AUTHOR]

In this work, metallic 1T-MoS 2 /polyaniline (PANI) heterostructures with unique alternating arrangement are fabricated via an electrostatic attraction-induced self-assembly approach. Negatively charged metallic 1T-MoS 2 monolayers are first obtained by chemical exfoliation, followed by the mixing with PANI and acidification. The neutralization of surface charges triggers spontaneous self-assembly, leading to the formation of alternating stacked 1T-MoS 2 /PANI heterostructures. Such unique architecture maximizes the interfacial contact between metallic 1T-MoS 2 and PANI and enhances synergistic effect between them. The close atomic contact not only greatly improves the electron and ion transport of the nanocomposites, but also gives rise to good structural stability due to the strong interactions between the intimately contacted 1T-MoS 2 and PANI. Furthermore, the compatibility of the nanocomposites with the aqueous electrolyte is also greatly improved. As a result, high specific capacitance and excellent cycling stability are achieved when the heterostructures are studied as electrode materials in supercapacitors. The capacitance retention is up to 91% at 10 A/g after 2000 cycles. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we report a novel fullerene–polyaniline emeraldine base (C60–PANI-EB) hybrid synthesized through covalent bonding of polyaniline (PANI) onto para-phenylenediamine (PPD)-functionalized fullerene and its capacity properties. C60–PANI-EB exhibits a unique coral-like porous morphology with PANI particles interconnected by nanofibers. In comparison with polyaniline emeraldine base (PANI-EB), C60–PANI-EB shows significantly higher specific capacitance, specific power and specific energy, and better cycling stability. The specific capacitance of C60–PANI-EB and PANI-EB are 776Fg−1 and 492Fg−1 at current density of 1mAcm−2, respectively. The specific capacitance of C60–PANI-EB has 37% enhancement over that of PANI-EB even at high current density of 100mAcm−2. The specific energy of C60–PANI-EB is 64Whkg−1 at 1mAcm−2 and the specific power is 36,595Wkg−1 at current density of 100mAcm−2. The greatly enhanced capacity performance can be attributed to the increased ionic conductivity induced by the loose molecular packing structure and porous morphology as well as the increased electrical conductivity caused by the coral-like interconnected morphology and the strong electron-withdrawing function of the fullerene through its covalent bonding to PANI. [Copyright &y& Elsevier]

Abstract: In this article, fullerene covalently bonded with multiple polyaniline (PANI) arms (C60-PANI) was readily synthesized via copolymerization of aniline with p-phenylenediamine (PPD) functionalized fullerene in the presence of poly(styrene sulfonate) (PSS) dopant agent in an aqueous medium to produce a water-processable electrochromic material. The PSS-doped C60-PANI (C60-PANI:PSS) film possesses finer morphology in comparison with PSS-doped PANI (PANI:PSS) film. Owing to the electron acceptor characteristic and high conductivity of fullerene as well as the loose morphology of C60-PANI:PSS, the synthesized hybrids exhibit simultaneously enhanced electrical and ionic conductivities, resulting in improvement of electrochromic performance. In particular, the electrochromic device with C60-PANI:PSS as the active layer shows significant enhancement in optical contrast and electrochemical stability over the PANI:PSS-based device. [Copyright &y& Elsevier]

Abstract: Poly(styrene sulfonate) (PSS) tethered polyhedral oligomeric silsesquioxane (POSS-PSS) was synthesized and used as star-like dopant for the preparation of core–shell polyaniline/POSS-PSS (PANI/POSS-PSS) nanoparticles. The prepared aqueous emulsion shows good processibility and high stability. The electrochemical characteristics and electrochromic properties of PANI/POSS-PSS were studied. In comparison with polyaniline (PANI) doped with linear PSS dopant, the star-like POSS-PSS dopant renders PANI/POSS-PSS-based electrochromic device higher optical contrast and faster switching speed owing to the faster ion transportation resulting from the porous morphology of PANI/POSS-PSS. [Copyright &y& Elsevier]

Abstract: In this paper we report a high-contrast complementary electrochromic device based on polyaniline-tethered polyhedral oligomeric silsesquioxane (POSS-PANI) and tungsten oxide (WO3). The electrochromic properties, cyclic voltammetry behavior and coloration efficiency of the device are studied. Due to the loosely packed structure of POSS-PANI, it possesses more accessible doping sites and hence gives rise to a significantly higher electrochromic contrast than polyaniline (PANI). Furthermore, the replacement of PANI with POSS-PANI as the complementary layer for WO3 leads to an enhanced complementary effect, for which the underneath mechanism is also discussed. [Copyright &y& Elsevier]

Abstract: A new series of electrochromic polymers are synthesized via oxidative emulsion copolymerization of hexa(4-aminophenoxy)cyclotriphosphazene (HACP) and aniline in the presence of dodecylbenzene sulfonic acid. The structures of the copolymers are characterized using nuclear magnetic resonance spectroscopy, size exclusion chromatography, wide angle X-ray diffraction, scanning and transmission electron microscopy. The results reveal that the copolymer containing 4.0mol % HACP (4.0% HACP–PANI) possesses a large number of nanometer-sized crystallites due to the unique molecular architecture of HACP–PANI. Spectro-electrochemical studies show that 4.0% HACP–PANI exhibits a significant enhancement in electrochromic contrast as compared with homopolyaniline (PANI). The contrast enhancement can be attributed to the easier diffusion of cations into nanometer-sized crystals, which is evidenced by a significant increase in ionic conductivity. At lower HACP concentrations, the copolymers induce the crystallization of linear PANI as substantial amounts of PANI may form during the polymerization, resulting in increased crystal size, and hence low electrochromic contrasts. [Copyright &y& Elsevier]

Abstract: We report the structures, electrochemical and electrochromic properties of organic–inorganic hybrid polymers prepared via copolymerization of octa(aminophenyl) silsesquioxane and aniline. Compared with homopolyaniline (PANI), this class of novel materials exhibits much greater thermodynamic penetrability in solution, as detected using static and dynamic light scattering, suggesting that they have a star-like molecular geometry. Due to their star-like geometry, in solid state the copolymers (POSS–PANI) exhibit a loosely packed structure with relatively low crystallinity, as evidenced by X-ray and TEM characterization, and hence relatively high ionic conductivity. Cyclic voltammetric studies show that POSS–PANI undergoes similar electrochemical reactions to that of PANI but its loosely packed structure allows slightly faster cation diffusion. Spectro-electrochemical studies show a ∼40% enhancement in electrochromic contrast brought by tethering PANI onto POSS, which can be attributed to more accessible doping sites in POSS–PANI. Furthermore, the electrochemical stability of POSS–PANI is also significantly improved over that of PANI. Infrared spectroscopic measurements indicate that the formation of electrochemically inactive quinonediimine is retarded in POSS–PANI possibly due to the increased conformation freedom of the dopant anions. [Copyright &y& Elsevier]