Syntheses of electroactive layers based on functionalized anthracene for electrochromic applications

A new monomer (DTAT) was synthesized via linking 3,4-ethylenedioxythiophene (EDOT) on anthracene. The polymer, P(DTAT) was electrosynthesized by anodic oxidation of the corresponding monomer in 0.1 M LiClO₄ acetonitrile (ACN) solution. The optical properties, the absorption spectra and the kinetics, were examined. Spectroelectrochemical analysis showed that P(DTAT) has an electronic band gap (due to π-π* transition) of 1.57 eV at 776 nm.Copolymers of DTAT with EDOT were prepared in ACN/LiClO₄ (0.1 M) solvent-electrolyte couple by varying applied potential. The incorporation of an EDOT into the full conjugated backbone, DTAT, affects its optical behavior resulting in different colors; a claret red neutral state, gray and red intermediate states and a blue oxidized state.     

Hyperbranched conjugated polymers for photovoltaic applications

Three hyperbranched phenylene vinylenes (HPVs)—H‐mn, H‐es, and H‐py—were used in fabricating polymer photovoltaic cells (PVCs). PVCs with photoactive layers composed of pure HPV, a blend of HPV and C₆₀, and a blend of HPV, poly(2‐methoxyl‐5,2′‐ethylhexyoxyl‐1,4‐phenylene vinylene) (MEH‐PPV), and C₆₀, were fabricated, and their current–voltage characteristics were measured and investigated. The PVC with photoactive layers composed of H‐es and C₆₀ showed promising photovoltaic characteristics, with an energy‐conversion efficiency of 0.035%, when illuminated under 85 mW/cm² white light. The short‐circuit current and energy‐conversion efficiency of the PVCs based on H‐mn/C₆₀ and H‐py/C₆₀ were greatly improved when they were blended with a small amount of MEH‐PPV. The incident photon‐to‐collected‐electron efficiency of the HPV/MEH‐PPV/C₆₀ PVCs indicated that both HPVs and MEH‐PPV contributed to the photocurrent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1459–1466, 2004     

Electrostatic layer-by-layer and electrophoretic depositions as methods for electrochromic nanoparticle immobilization

The present paper describes the immobilization of nanoparticles onto conducting substrates by using both electrostatic layer-by-layer and electrophoretic deposition (EPD) methods. These two techniques were compared in high-performance electrochromic electrodes based on mixed nickel hydroxide nanoparticles. In addition to easy handling, EPD seems to be the most suitable method for the immobilization of nanoparticles, leading to higher electrochromic efficiencies, lower response times and higher stability upon coloration and bleaching cycling.     

D-A type hybrid polymers based on EDOT and various benzodiazoles for electrochromic materials

Two donor units (D)-acceptor units (A) type monomers were synthesized by Stille coupling reaction, and then three D-A type hybrid polymers based on 3,4-ethylenedioxythiophene and various benzodiazoles were synthesized by electrochemical polymerization. Spectroelectrochemical and kinetic studies of these polymers showed that all polymer films exhibited excellent electrochromic behavior, obvious optical contrast, and excellent stability. Among them, the response time of P3 film was the shortest (t_c = 1.6 s, t_b = 2.2 s), the coloring efficiency of P2 film was the highest (CE = 333 cm²·C⁻¹), and the stability of P1 was the best (the ΔT loss of P1 after 1000 s cycles is only 2.3%). Therefore, these data prove that these new polymers have great potential in applications as electrochromic materials.     

Electrochromic properties of porous NiO thin film as a counter electrode for NiO/WO3 complementary electrochromic window

Highly porous nickel oxide (NiO) thin films were prepared on ITO glass by chemical bath deposition (CBD) method. SEM results show that the as-deposited NiO film is constructed by many interconnected nanoflakes with a thickness of about 20 nm. The electrochromic properties of the NiO film were investigated in a nonaqueous LiClO₄–PC electrolyte by means of optical transmittance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The NiO film exhibits a noticeable electrochromic performance with a variation of transmittance up to 38.6% at 550 nm. The CV and EIS measurements reveal that the NiO film has high electrochemical reaction activity and reversibility due to its highly porous structure. The electrochromic (EC) window based on complementary WO₃/NiO structure shows an optical modulation of 83.7% at 550 nm, much higher than that of single WO₃ film (65.5% at 550 nm). The response time of the EC widow is found to be about 1.76 s for coloration and 1.54 s for bleaching, respectively. These advantages such as large optical modulation, fast switch speed and excellent cycle durability make it attractive for a practical application.     

Synthesis and spectroelectrochemical investigation of low‐bandgap polymer: Integrated quinoxaline and benzimidazole in one electron acceptor unit

Two novel π‐conjugated monomers, 6‐(4‐octyloxyphenyl)‐4,8‐bis(thiophene‐2‐yl)‐3H‐[d] imidazole[1,2,5] benzothiadiazole (M3) and 4‐(4‐octyloxyphenyl)‐2,6‐bis(thiophene‐2‐yl)‐3H‐[d] imidazole‐acenaphtho[1,2‐b]quinoxaline (M4), were synthesized. The monomer M4 contains a thiophene electron‐donating unit and electron withdrawing unit in which quinoxaline and benzimidazole integrated in one benzene ring. Electrochemical polymerization of the monomers was carried out in acetonitrile/dichloromethane solvent mixture containing tetra‐n‐butylammonium hexafluorophosphate and electrochromic properties of polymers (P3 and P4) are described in this article. Furthermore, the effects of structural difference on electrochemical redox behavior and spectroelectrochemical properties of the two resulting polymers were examined. The results showed that an anodic wave at +0.48 V versus Ag wire pseudo‐reference electrode corresponding to the monomer M4 oxidation was observed, while one anodic wave at +0.70 V was observed in oxidation of M3 as it contains stronger electron withdrawing thiadiazole structure. The UV‐vis‐Near‐infrared (Near‐infrared spectroscopy) (NIR) spectra analysis revealed that the two polymers have one absorbance band centered at 603 nm. The band gaps, defined as the onset of the absorption band at 603 nm of these polymers, were determined as 1.60 eV for P3 and as 1.55 eV for P4. The electrochromic results showed that P3 revealed about 20% optical contrast at 980 nm and the P4 has 30% optical contrast at 806 nm with low response time (1 s for each polymer). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40861.     

Effect of different precursor sols on the properties of CeO2-TiO2 films for electrochromic window applications

The properties of spin coated CeO₂-TiO₂ films derived from three different sols containing equimolar quantities of cerium and titanium, fired at 500 °C have been investigated. The films have been deposited using cerium chloride and two different alkoxides and the influence of acetic acid added as a catalyst and modifier of microstructure of the coatings has also been studied. Optical, structural, thermal, and electrochemical properties have been studied and compared. Although gelation time of sols is dependent on the precursor material, enhanced transparency is exhibited by the films prepared with all the sols that have reached the state of gelation. The crystallization behavior and the porosity of the films are highly influenced by the precursor material. Acetic acid derived films with the highest porosity exhibit the highest diffusion coefficient for Li ions. Amorphicity prevailing in films derived from Ti propoxide based precursor sol as against the nanocrystalline films derived from the other sols endow higher ion insertion capacity to former films and highest coloration efficiency is attained when these films are incorporated into an electrochromic device. The highest reversibility for the charging and discharging processes and excellent electrochemical properties observed for the film derived from titanium propoxide prove its practical utility in electrochemical applications. Besides, the highest optical modulation for the electrochromic device comprising WO₃ (electrochromic electrode) and titanium propoxide derived counter electrode is a manifestation of the suitability of the latter electrode in electrochromic window applications.     

Corrosion inhibitors part V: QSAR of benzimidazole and 2-substituted derivatives as corrosion inhibitors by using the quantum chemical parameters

Quantum chemical SCF calculations of some parameters of benzimidazoles were correlated with their inhibition efficiency in case of steel in aqueous acidic medium. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular orbital (E_HOMO), lowest unoccupied molecular orbital (E_LUMO), dipole moment (μ) and linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (π*) were correlated to corrosion inhibition efficiency. The correlation between quantum parameters obtained by AM1 calculation and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM1 structure using B3LYP/6-31G* as a higher level of theory. Equations were proposed using linear regression analysis to calculate corrosion inhibition efficiency. It was established that the increase of the orbital energies E_HOMO favors the inhibition efficiency toward steel corrosion. The proposed linear equations were applied to predict the corrosion inhibition efficiency of some related structures in order to select molecules of possible activity from a library compounds.     

Acetophenone and thiophene side‐arm polyaryleneethynylene conjugated polymers for enrichment of electronic applications

In the present work, a new type of semiconducting acetophenone and thiophene side‐arm based polyaryleneethynylene (PAE) conjugated polymers (CPs) were synthesized using the Heck–Sonogashira cross‐coupling reaction. The new type of monomers and APAEC₈, APAEC₁₂, APAEF₈, TPAEC₈, TPAEC₁₂, and TPAEF₈ (PAE CPs) were synthesized and characterized using Fourier transform IR, NMR and high resolution mass spectrometry studies. The average molecular weight of the CPs was determined using gel permeation chromatography. The data obtained from optical properties in the UV–visible and photoluminescence spectral studies were used to calculate the values of the Stokes shift. Among the six CPs studied, TPAEC₈ was found to possess a lower optical band gap (E_g = 2.112 eV) than those of the other CPs. The data obtained from different studies, it was found that TPAEC₈ exhibits better properties than the other CPs and can be used in the field of organic based photonic, electronic and other sensor applications. © 2020 Society of Chemical Industry     

Direct arylation polycondensation as simplified alternative for the synthesis of conjugated (co)polymers

Future application of conjugated (co)polymers, e.g. in electronic devices, requires the availability of up-scalable synthetic procedures. “Conventional” (hetero)aryl-(hetero)aryl coupling schemes often produce toxic or environmentally risky by-products. Here, so-called direct arylation schemes without use of organometallic reagents or related anion equivalents came in the focus of attention as simplified alternative to standard coupling procedures. Now, a couple of structurally defined conjugated (co)polymers can be generated in high yield and molecular weight via direct arylation polycondensation. The promising application potential of these materials as active component of organic solar cells has been demonstrated.     

Two-photon absorption properties of hyperbranched conjugated polymers with triphenylamine as the core

Two new hyperbranched phenylene vinylenes (HPVs) with triphenylamine as the core, 2,5-dihexyloxyl substituted phenylene vinylene as the connecting unit, and electron-donating triphenylamine or electron-deficient nitrobenzene as the different terminal groups were synthesized by modified Wittig polymerization reaction. Their one- and two-photon absorption (TPA) properties have been investigated. The two-photon absorption cross sections of the two polymers were performed by open-aperture Z-scan experiment using 120 femtosecond (fs) pulse, and their TPA cross section were determined to be 1.43 and 0.64×10⁻²⁰ cm⁴/GW per repeating unit at 800 nm, respectively. In chloroform, HPVs exhibit intense frequency up-converted fluorescence under the excitation of 120 fs pulses at 800 nm with the peaks located at 544 and 554 nm, respectively.     

Polysiloxaneurethanes: new polymers for potential coating applications

Polysiloxaneurethanes (PSUR) are block copolymers containing polysiloxane and urethane (or polyurethane) segments and showing very interesting mechanical, dielectric and surface related properties. Brief reviews of investigations that have been carried out so far on PSUR are presented with special reference to coating applications of them. The properties of the novel moisture-curable PSUR (MCPSUR), tested before and after moisture curing, are discussed in connection with their chemistry and structure. The properties of aqueous dispersions of PSUR (ADPSUR) synthesised in ICRI are also reviewed. The preliminary results of some coating tests made for MCPSUR and ADPSUR are presented.     

Trends in sputter deposited tungsten oxide structures for electrochromic applications: A review

Electrochromic devices (ECD) show reversible color change under applied electric field and are predicted to become indispensable in many applications such as low power displays, smart windows to develop energy-saving buildings as well as light-adapting mirrors in high-end cars and aircrafts. Despite the assiduous research work, ECD faces several challenges for practical usage including delamination, durability, lifetime and their integration into multifunctional devices. To improve the performance, different techniques have already been used to deposit single-layered thin film, or a stack of promising EC layers on several substrates including transparent conductive oxides (TCO) coated glass and different conducting polymers. These layers can be flat enough or have a definite shape or structure to satisfy the needs of the designed device. Based on their low resistivity and high transparency, fluorine and indium doped tin oxides (FTO, ITO) are mostly used as TCOs whereas polyaniline, polypyrrole and ethylenedioxythiophene are the trending future polymers. In this review, the critical parameters of magnetron sputtering are delineated for the deposited tungsten oxide (WO₃) films focused on ITO and FTO layered glass. The main focus of interest is to highlight the recent progress and future trends in this technique, structure introduced with sputtered electrochromic film and their carefully review along with effect of altering these parameters on physical, optical, electrochemical, durability and thus overall performance of the ECD. Finally, it will be intended to underline the future perspectives in realizing smart EC devices with various factual characteristics.     

Aminic epoxy resin hardeners as reactive solvents for conjugated polymers: polyaniline base/epoxy composites for anticorrosion coatings

Polyaniline (PANI) has much been studied in the context of corrosion prevention, particularly on steel and aluminium. To prepare epoxy coatings consisting of PANI has turned to be nontrivial, due to its relatively rigid conformation and poor solubility. Therefore, as the aim has typically been first to dissolve PANI in the epoxy component before curing, auxiliary solvents have been required, and less attractive Lewis-type hardeners have been required if the conducting salt form has been used. In this work, we describe a particularly simple concept where emeraldine base (EB) form of PANI is first dissolved in specific aminic hardeners which are observed to be solvents for EB at low concentrations, and the mixtures are unconventionally cross-linked upon adding epoxy resin, diglycidyl ether of bisphenol-A (DGEBA). Suitable hardeners are N,N,N′,N′-tetrakis(3-aminopropyl)-1,4-butanediamine (DAB-AM-4) and trimethylhexanediamine (TMDA). Even if the subsequent cross-linking promotes phase separation, the forming cross-link sites may also control the phase separation. As a result, sufficiently homogeneous coatings are identified which contain only 1 wt% EB in the cured EB/DGEBA/TMDA composites where in aqueous 3.5% NaCl solution the corrosion front propagation is suppressed, and electrochemical impedance studies indicate the formation of a charged interface or reaction product layer between EB and steel. For reference, similar net EB/DGEBA/TMDA-compositions were prepared, where EB was first mixed in DGEBA without any solubility and which were cured by added TMDA, and they gave essentially no anticorrosion effect. We expect that the present concept opens new ways to prepare cured epoxy composites also with other conjugated or nonconjugated polymers for anticorrosion and other functional purposes.     

Improved performance of a protein array using conjugated polymers as capture phase for HIV serodiagnosis

A modified recombinant protein derived from the viral capsid of the human immunodeficiency virus (HIV) was coupled to a copolymer of maleic anhydride and methyl vinyl ether (MAMVE). The conjugated copolymer was spotted versus free protein in 96‐well microplates. The conjugated copolymer largely improved detection sensitivity of anti‐P24 antibodies in infected human sera. Results obtained with immuno‐linked sorbent array (ILISA) were correlated with those generated with a standard enzyme‐linked immunosorbent assay (ELISA). Serum dilution dynamic range was varied from 1/5000 to 1/150, and inter‐well coefficient of variation was below 8%. Copyright © 2004 Society of Chemical Industry     

Outstanding performance of parylene polymers as electrets for energy harvesting and high-temperature applications

Parylene C is used in many applications due to its high properties but it remains a material with moderate performance as long as it is intended for use as an electret. Hence, the generally accepted idea, rightly so, in the scientific and industrial community not to necessarily select parylene (i.e., parylene C) for applications where the endurance of the electret is a strong criterion. Our study provided a new perspective on the performance of parylenes as electret. In this case, we will talk about fluorinated Parylenes of the VT-4 type and especially AF-4 variant. Their thermal stability is outstanding and a charge stability is almost total up to 100 °C. A 50% reduction in the charge is recorded at a temperature as high as of 220 °C (9 μm thick Parylene AF-4), making it one of the most efficient polymer electrets to date. Negatively and positively charged Parylene AF-4 electrets presented similar performance over long durations, which is out of ordinary for the commonly employed polymeric electrets. Finally, these fluorinated polymers are therefore particularly promising new candidates for applications in electret-based converters for energy harvesting. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48790.     

Modification of polysiloxane polymers for biomedical applications: a review

This paper reviews methods of modifying polydimethylsiloxane (PDMS) polymers to improve their properties for biomedical applications. The modification methods are discussed under three different categories: bulk, surface and other modification techniques. Surface modification techniques include physical and chemical techniques to modify polymer surfaces. Bulk modification techniques include blending, copolymerization, interpenetrating polymer networks (IPNs) and functionalization. The third category includes less common modification techniques. © 2001 Society of Chemical Industry     

Review of electronic and optical properties of semiconducting π‐conjugated polymers: applications in optoelectronics

A general overview of the optoelectronic properties of π‐conjugated polymers is presented. Two types of polymer are discerned: interchangeable structures of the same energy (degenerate), such as polyacetylene; and non‐degenerate polymers, such as poly(para‐phenylene). The band structures of degenerate and non‐degenerate polymers are related to their conductivities in doped and non‐doped states. In both cases, disorder and impurities play an important role in conductivity. Polarons, bipolarons and excitons are detailed with respect to doping and charge transfers. Given the fibrillic nature of these materials, the variable range hopping (VRH) law for semiconducting polymers is modified to account for metallic behaviours. Optoelectronic properties—electroluminescence and photovoltaic activity—are explained in terms of HOMO and LUMO bands, polaron‐exciton and charge movement over one or more molecules. The properties of H‐ or J‐type aggregates and their effects on transitions are related to target applications. Device structures of polymer light‐emitting diodes are explicitly linked to optimising polaron recombinations and overall quantum efficiencies. The particularly promising use of π‐conjugated polymers in photovoltaic devices is discussed. Copyright © 2004 Society of Chemical Industry     

Syntheses and properties of electroluminescent polyfluorene-based conjugated polymers, containing oxadiazole and carbazole units as pendants, for LEDs

New polyfluorenes (PF)-based conjugated copolymers, containing oxadiazole and carbazole units as pendants, were prepared as the electroluminescent (EL) layer in light-emitting diodes (LEDs) to show that most of them have higher maximum brightness and EL efficiency as compared to poly(2,7-(9,9-bis(2-ethylhexyl)fluorene)) (PF2/6). The prepared polymers, poly[(9-(6-(N-carbazolyl)-hexyl)-9-hexyl)-fluorene-2,7-diyl]-co-[(9-hexyl-9-(6-(4-(5-phenyl-1,3,4-oxadiazolyl)-phenoxy)-hexyl)-fluorene-2,7-diyl)] (Oxd-PF-co-Cz-PF), were soluble in common organic solvents and used as the EL layer in double layer light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Al). All polymers show photoluminescence around λ_max=430 nm (exciting wavelength, 370 nm) and blue EL around λ_max=426 nm. The current–voltage–luminance (I–V–L) characteristics of the polymers show turn-on voltages of 3.5–5.5 V which are lower than that of PF2/6. The maximum brightness and EL efficiency of the device with the configuration of ITO/PEDOT/polymer/Al were 3000 cd/m² at 10 V and 2.13 cd/A at 10.6 mA/cm², respectively, which are all higher than those of PF2/6.