Impact of polyethyleneglycol addition on diffusion coefficients in binary ionic liquid electrolytes composed of dicationic ionic liquid and polyethyleneglycol.

We conduct a comparative study of conductivity and diffusion coefficient of two dicationic ionic liquids (3,3'-(octane-1,8-diyl)bis(1-ethyl-3-imidazolium) bis(trifluoromethylsulfonyl)amide ([IMCI][TFSI], S1) and 3,3'-(2,2'-(ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl))bis(1-ethyl-3-imidazolium) bis(trifluoromethylsulfonyl)amide ([IMOI][TFSI], S2)) at various temperatures. The diffusion coefficients of cation and anion in ionic liquids are determined by using pulse gradient spin-echo nuclear magnetic resonance method. S2 shows lower viscosity, higher conductivity, and higher diffusion coefficient than those of S1. Moreover, the influence of polyethyleneglycol (PEG200, Mw  = 200) addition in PEG200/IL binary solutions is investigated. PEG200/S1 binary solutions show lower viscosity, higher conductivity, and higher diffusion coefficient than those of neat S1. The experimental molar conductivity (Λ) of neat IL and PEG200/IL binary solutions is lower than that of the calculated molar conductivity (ΛNMR ) from pulse gradient spin-echo nuclear magnetic resonance method at various temperatures, indicating that not all the diffusion species belong to the ionic conduction. In other words, NMR diffusion measurements comprise charged and paired (without charge) ions. Copyright © 2017 John Wiley & Sons, Ltd.

Engineering of Aromatic Naphthalene and Solvent Molecules to Optimize Chemical Prelithiation for Lithium-Ion Batteries.

A cost-effective chemical prelithiation solution, which consists of Li+, polyaromatic hydrocarbon (PAH), and solvent, is developed for a model hard carbon (HC) electrode. Naphthalene and methyl-substituted naphthalene PAHs, namely 2-methylnaphthalene and 1-methylnaphthalene, are first compared. Grafting an electron-donating methyl group onto the benzene ring can decrease electron affinity and thus reduce the redox potential, which is validated by density functional theory calculations. Ethylene glycol dimethyl ether (G1), diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether solvents are then compared. The G1 solution has the highest conductivity and least steric hindrance, and thus the 1-methylnaphthalene/G1 solution shows superior prelithiation capability. In addition, the effects of the interaction time between Li+ and 1-methylnaphthalene in G1 solvent on the electrochemical properties of a prelithiated HC electrode are investigated. Nuclear magnetic resonance data confirm that 10-h aging is needed to achieve a stable solution coordination state and thus optimal prelithiation efficacy. It is also found that appropriate prelithiation creates a more Li+-conducing and robust solid-electrolyte interphase, improving the rate capability and cycling stability of the HC electrode.

Pretreatment of lignocellulosic biomass from sugar bagasse under microwave assisted dilute acid hydrolysis for biobutanol production.

Alternative renewable energy sources are the future potential energy that will benefit the country's overall energy shortage and demand. The efficient biofuel production depends on the viability of the raw material used. The holistic approach of this study is to establish an integrated bioprocess from lignocellulosic material for biofuel synthesis. Sugar bagasse as one of the waste material, can be economically process for sugar extraction used in biofuel production. In this study, the optimum saccharification rate obtained was 43.62% when the biomass was pretreated at microwave temperature of 100 °C for 15 min with 2.5 g catalyst concentration. The results attained shows that hydrolysis time reduces to approximately 40-50% in compare with other traditional heating method. The sample was analyzed by using UV spectrophotometer and HPLC and computed by using Response Surface Method in MINITAB 17, whereas the structural changes of the residue was detected by using ATR-FTIR and ESEM.

1,4-Bis((9H-Carbazol-9-yl)Methyl)Benzene-Containing Electrochromic Polymers as Potential Electrodes for High-Contrast Electrochromic Devices.

Four 1,4-bis((9H-carbazol-9-yl)methyl)benzene-containing polymers (PbCmB, P(bCmB-co-bTP), P(bCmB-co-dbBT), and P(bCmB-co-TF)) were electrosynthesized onto ITO transparent conductive glass and their spectral and electrochromic switching performances were characterized. The PbCmB film displayed four types of color variations (bright gray, dark gray, dark khaki, and dark olive green) from 0.0 to 1.2 V. P(bCmB-co-bTP) displayed a high transmittance variation (∆T = 39.56% at 685 nm) and a satisfactory coloration efficiency (η = 160.5 cm2∙C-1 at 685 nm). Dual-layer organic electrochromic devices (ECDs) were built using four bCmB-containing polycarbazoles and poly(3,4-ethylenedioxythiophene) (PEDOT) as anodes and a cathode, respectively. PbCmB/PEDOT ECD displayed gainsboro, dark gray, and bright slate gray colors at -0.4 V, 1.0 V, and 2.0 V, respectively. The P(bCmB-co-bTP)/PEDOT ECD showed a high ∆T (40.7% at 635 nm) and a high coloration efficiency (η = 428.4 cm2∙C-1 at 635 nm). The polycarbazole/PEDOT ECDs exhibited moderate open circuit memories and electrochemical redox stability. The characterized electrochromic properties depicted that the as-prepared polycarbazoles had a satisfactory application prospect as an electrode for the ECDs.

Effect of temperature on the physico-chemical properties of a room temperature ionic liquid (1-Methyl-3-pentylimidazolium hexafluorophosphate) with polyethylene glycol oligomer.

A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF(6)] with poly(ethylene glycol) (PEG) [M(w) = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values.

Efficient H-NMR quantitation and investigation of N-acetyl-d-glucosamine (GlcNAc) and N,N'-diacetylchitobiose (GlcNAc)(2) from chitin.

A quantitative determination method of N-acetyl-d-glucosamine (GlcNAc) and N,N'-diacetylchitobiose (GlcNAc)(2) is proposed using a proton nuclear magnetic resonance experiment. N-acetyl groups of GlcNAc and (GlcNAc)(2) are chosen as target signals, and the deconvolution technique is used to determine the concentration of the corresponding compound. Compared to the HPLC method, (1)H-NMR spectroscopy is simple and fast. The method can be used for the analysis of chitin hydrolyzed products with real-time analysis, and for quantifying the content of products using internal standards without calibration curves. This method can be used to quickly evaluate chitinase activity. The temperature dependence of (1)H-NMR spectra (VT-NMR) is studied to monitor the chemical shift variation of acetyl peak. The acetyl groups of products are involved in intramolecular H-bonding with the OH group on anomeric sites. The rotation of the acetyl group is closely related to the intramolecular hydrogen bonding pattern, as suggested by the theoretical data (molecular modeling).

Physicochemical properties of glycine-based ionic liquid [QuatGly-OEt][EtOSO(3)] (2-Ethoxy-1-ethyl-1,1-dimethyl-2-oxoethanaminium ethyl sulfate) and its binary mixtures with poly(ethylene glycol) (M(w) = 200) at various temperatures.

This work includes specific basic characterization of synthesized glycine-based Ionic Liquid (IL) [QuatGly-OEt][EtOSO(3)] by NMR, elementary analysis and water content. Thermophysical properties such as density, ρ, viscosity, η, refractive index, n, and conductivity, κ, for the binary mixture of [QuatGly-OEt][EtOSO(3)] with poly(ethylene glycol) (PEG) [M(w) = 200] are measured over the whole composition range. The temperature dependence of density and dynamic viscosity for neat [QuatGly-OEt][EtOSO(3)] and its binary mixture can be described by an empirical polynomial equation and by the Vogel-Tammann-Fucher (VTF) equation, respectively. The thermal expansion coefficient of the ILs is ascertained using the experimental density results, and the excess volume expansivity is evaluated. The negative values of excess molar volume for the mixture indicate the ion-dipole interactions and packing between IL and PEG oligomer. The results of binary excess property (V(m) (E) ) and deviations (Δη, Δ(x)n, Δ(Ψ)n, Δ(x)R, and Δ(Ψ)R) are discussed in terms of molecular interactions and molecular structures in the binary mixture.

Effects of morphology and pore size of mesoporous silicas on the efficiency of an immobilized enzyme.

An investigation is performed into the efficiency of the Streptomyces griseus HUT 6037 enzyme immobilized in three different mesoporous silicas, namely mesoporous silica film, mesocellular foam, and rod-like SBA-15. It is shown that for all three supports, the pH value changes the surface charge and charge density and hence determines the maximum loading capacity of the enzyme. The products of the enzyme hydrolytic reaction are analyzed by 1H-NMR. The results show that among the three silica supports, the mesoporous silica film (with a channel length in the range of 60-100 nm) maximizes the accessibility of the immobilized enzyme. The loading capacity of the enzyme is up to 95% at pH 7 and the activity of the immobilized enzyme is maintained for more than 15 days when using a silica film support. The order of the activity of the enzyme immobilized in different mesoporous silica supports is: mesoporous silica film > mesocellular foam > rod-like SBA-15. Furthermore, the immobilized enzyme can be easily separated from the reaction solution via simple filtration or centrifugation methods and re-used for hydrolytic reaction as required.

Electrodeposited Copolymers Based on 9,9'-(5-Bromo-1,3-phenylene)biscarbazole and Dithiophene Derivatives for High-Performance Electrochromic Devices.

A 1,3-bis(carbazol-9-yl)benzene derivative (BPBC) was synthesized and its related homopolymer (PBPBC) and copolymers (P(BPBC-co-BT), P(BPBC-co-CDT), and P(BPBC-co-CDTK)) were prepared using electrochemical polymerization. Investigations of polymeric spectra showed that PBPBC film was grey, iron-grey, yellowish-grey, and greyish-green from the neutral to the oxidized state. P(BPBC-co-BT), P(BPBC-co-CDT), and P(BPBC-co-CDTK) films showed multicolor transitions from the reduced to the oxidized state. The transmittance change (ΔT) of PBPBC, P(BPBC-co-BT), P(BPBC-co-CDT), and P(BPBC-co-CDTK) films were 29.6% at 1040 nm, 44.4% at 1030 nm, 22.3% at 1050 nm, and 41.4% at 1070 nm. The coloration efficiency (η) of PBPBC and P(BPBC-co-CDTK) films were evaluated to be 140.3 cm2 C-1 at 1040 nm and 283.7 cm2 C-1 at 1070 nm, respectively. A P(BPBC-co-BT)/PEDOT electrochromic device (ECD) showed a large ΔT (36.2% at 625 nm) and a fast response time (less than 0.5 s), whereas a P(BPBC-co-CDTK)/PEDOT ECD revealed a large η (534.4 cm2 C-1 at 610 nm) and sufficient optical circuit memory.

Electrosynthesis of Electrochromic Polymer Membranes Based on 3,6-Di(2-thienyl)carbazole and Thiophene Derivatives.

Five carbazole-containing polymeric membranes (PDTC, P(DTC-co-BTP), P(DTC-co-BTP2), P(DTC-co-TF), and P(DTC-co-TF2)) were electrodeposited on transparent conductive electrodes. P(DTC-co-BTP2) shows a high ΔT (68.4%) at 855 nm. The multichromic properties of P(DTC-co-TF2) membrane range between dark yellow, yellowish-green, gunmetal gray, and dark gray in various reduced and oxidized states. Polymer-based organic electrochromic devices are assembled using 2,2'-bithiophene- and 2-(2-thienyl)furan-based copolymers as anodic membranes, and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS) as the cathodic membrane. P(DTC-co-TF)/PEDOT-PSS electrochromic device (ECD) displays a high transmittance change (ΔT%) (43.4%) at 627 nm as well as a rapid switching time (less than 0.6 s) from a colored to a bleached state. Moreover, P(DTC-co-TF2)/PEDOT-PSS ECD shows satisfactory optical memory (the transmittance change is less than 2.9% in the colored state) and high coloration efficiency (512.6 cm2 C-1) at 627 nm.

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and trace metals in the blood of nonoccupationally exposed residents living in the vicinity of a municipal solid waste incinerator and electric arc furnace.

This study examines levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and trace metals in the blood of the nonoccupationally exposed residents living in the vicinity of municipal solid waste incinerators (MSWIs) and electric arc furnaces (EAFs). The analysis found that older females had higher concentrations of PCDD/Fs and older males had higher body mass index (BMI) values and higher concentrations of PCDD/Fs. Moreover, sex appeared to affect the levels of PCDD/Fs because, overall, females showed higher levels of PCDD/Fs. The results of a principal component analysis indicated that the characteristics of the blood were more similar to the characteristics of the stack flux gas in MSWIs than those in EAFs. When sex, age, and BMI values were taken into consideration, none of the factors appeared to significantly affect PCDD/F and trace metal blood levels. However, when participants were divided into eight categories and analyzed, it was found that sex was the most important factor affecting levels of trace metals in blood and that males had higher concentrations of Pb, Al, Cd, and Cu.

Synthesis and characterization of organic dyes containing various donors and acceptors.

New organic dyes comprising carbazole, iminodibenzyl, or phenothiazine moieties, respectively, as the electron donors, and cyanoacetic acid or acrylic acid moieties as the electron acceptors/anchoring groups were synthesized and characterized. The influence of heteroatoms on carbazole, iminodibenzyl and phenothiazine donors, and cyano-substitution on the acid acceptor is evidenced by spectral, electrochemical, photovoltaic experiments, and density functional theory calculations. The phenothiazine dyes show solar-energy-to-electricity conversion efficiency (eta) of 3.46-5.53%, whereas carbazole and iminodibenzyl dyes show eta of 2.43% and 3.49%, respectively.

Carbonaceous Anodes Derived from Sugarcane Bagasse for Sodium-Ion Batteries.

To realize the sustainability of Na-ion batteries (NIBs) for large-scale energy storage applications, a resource-abundant and cost-effective anode material is required. In this study, sugarcane bagasse (SB), one of the most abundant types of biowaste, is chosen as the carbon precursor to produce a hard carbon (HC) anode for NIBs. SB has a great balance of cellulose, hemicellulose, and lignin, which prevents full graphitization of the pyrolyzed carbon but ensures a sufficiently ordered carbon structure for Na+ transport. Compared with HC derived from waste apples, which are pectin-rich and have less cellulose than SB, SB-derived HC (SB-HC) has fewer defects and a lower oxygen content. SB-HC thus has a higher first-cycle sodiation/desodiation coulombic efficiency and better cycling stability. In addition, SB-HC has a unique flake-like morphology, which can shorten the Na+ diffusion length, and higher electronic conductivity (owing to more sp2 -hybridized carbon), resulting in superior high-rate charge-discharge performance to apple-derived HC. The effects of pyrolysis temperature on the material characteristics and electrochemical properties, evaluated by using chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy, are systematically investigated for both kinds of HC.

Applications of Copolymers Consisting of 2,6-di(9H-carbazol-9-yl)pyridine and 3,6-di(2-thienyl)carbazole Units as Electrodes in Electrochromic Devices.

A series of carbazole-based polymers (PdCz, P(dCz2-co-dTC1), P(dCz2-co-dTC2), P(dCz1-co-dTC2), and PdTC) were deposited on indium tin oxide (ITO) conductive electrodes using electrochemical polymerization. The as-prepared P(dCz2-co-dTC2) displayed a high ΔT (57.0%) and multichromic behaviors ranging from yellowish green, greenish gray, gray to purplish gray in different redox states. Five organic electrochromic devices (ECDs) were built using dCz- and dTC-containing homopolymers and copolymers as anodic materials, and poly(3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProdot-Me2) as the cathodic material. The P(dCz2-co-dTC2)/PProdot-Me2 ECD presented remarkable electrochromic behaviors from the bleached to colored states. Moreover, P(dCz2-co-dTC2)/PProdot-Me2 ECD displayed a high optical contrast (ΔT, 45.8%), short switching time (ca. 0.3 s), high coloration efficiency (528.8 cm2 C-1) at 580 nm, and high redox cycling stability.

Isothermal and Nonisothermal Crystallization Kinetics of Poly(ε-caprolactone) Blended with a Novel Ionic Liquid, 1-Ethyl-3-propylimidazolium Bis(trifluoromethanesulfonyl)imide.

Recently, ionic liquids (ILs) and biodegradable polymers have become crucial functional materials in green sustainable science and technology. In this study, we investigated the influence of a novel IL, 1-ethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide ([EPrI][TFSI]), on the crystallization kinetics of a widely studied biodegradable polymer, poly(ε-caprolactone) (PCL). To obtain a comprehensive understanding, both the isothermal and nonisothermal crystallization kinetics of the PCL blends were studied. Incorporating [EPrI][TFSI] reduced the isothermal and nonisothermal crystallization rates of PCL. Regarding isothermal crystallization, the small k and 1/t0.5 values of the blend, estimated using the Avrami equation, indicated that [EPrI][TFSI] decreased the rate of isothermal crystallization of PCL. The Mo model adequately described the nonisothermal crystallization kinetics of the blends. Increasing the [EPrI][TFSI] content caused the rate-related parameter F(T) to increase. This indicated that the crystallization rate of PCL decreased when [EPrI][TFSI] was incorporated. The spherulite appearance temperature of the blending sample was found to be lower than that of neat PCL under a constant cooling rate. The analysis of the effective activation energy proposed that the nonisothermal crystallization of PCL would not be favorited when the [EPrI][TFSI] was incorporated into the blends. The addition of [EPrI][TFSI] would not change the crystal structures of PCL according to the results of wide angle X-ray diffraction. Fourier transform infrared spectroscopy suggested that interactions occurred between [EPrI][TFSI] and PCL. The crystallization kinetics of PCL were inhibited when [EPrI][TFSI] was incorporated.

Applications of Electrochromic Copolymers Based on Tris(4-carbazoyl-9-ylphenyl)amine and Bithiophene Derivatives in Electrochromic Devices.

Four copolymers (P(tCz (tris(4-carbazoyl-9-ylphenyl)amine)-co-bTP (2,2'-bithiophene)), P(tCz-co-CPDT (4H-cyclopenta[2,1-b:3,4-b']dithiophene)), P(tCz-co-DTC (3,6-di(2-thienyl)carbazole)), and P(tCz-co-CPDTK (cyclopentadithiophene ketone))) are deposited on indium tin oxide (ITO) surfaces using electrochemical polymerization. Spectroelectrochemical properties of copolymer electrodes reveal that the colors of P(tCz-co-bTP) film are pinkish-orange, light olive green, light grayish blue, and dark blue at 0.0, 0.8, 1.2, and 1.6 V, respectively, whereas the color variations of P(tCz-co-CPDTK) film are light yellow, yellow, and blue at 0.0 V, 0.8 V, and 1.5 V, respectively. The ΔT of P(tCz-co-bTP), P(tCz-co-CPDT), P(tCz-co-DTC), and P(tCz-co-CPDTK) films are estimated to be 43.0% at 967 nm, 28.7% at 864 nm, 43.6% at 870 nm, and 24.5% at 984 nm, respectively. Five electrochromic devices (ECDs) are assembled using the tCz-based homopolymer and copolymers as coloring electrodes, and poly(2,2-dimethyl-3,4-propylenedioxythiophene) (PProDOT-Me2) as the complementary electrode. P(tCz-co-DTC)/PProDOT-Me2 ECD reveals high transmittance change (45.9% at 624 nm), P(tCz-co-CPDTK)/PProDOT-Me2 ECD shows high η (513.0 cm² C-1 at 582 nm), and P(tCz-co-bTP)/PProDOT-Me2 ECD presents short switching time (less than 0.4 s) at 628 nm. Moreover, these ECDs show satisfactory redox stability and open circuit stability.

Synthesis and Properties of Magnetic Aryl-Imidazolium Ionic Liquids with Dual Brønsted/Lewis Acidity.

A series of unique tunable aryl-imidazolium magnetic ionic liquids (MILs) with dual acidity that contain both Brønsted and Lewis acidic sites (abbreviated as B-L MILs) were synthesized and characterized using nuclear magnetic resonance and mass spectrometry. Physical properties, such as thermal properties, magnetic susceptibility, and Brønsted and Lewis acidity, were measured. These properties were found to depend on the cation structure. These B-L MILs had good solubility in many organic solvents, good thermal stability, and low melting points, and exhibited magnet-like behavior. For these B-L MILs, the Brønsted acidity was measured using ultraviolet-visible (UV-Vis), and the Lewis acidity was measured using Fourier transform infrared spectroscopy (FTIR). The results showed that B-L MILs with an electron-withdrawing group in the aryl-imidazolium moiety had higher Brønsted acidity, whereas those with an electron-donating group had higher Lewis acidity. This type of ionic liquid, with both Brønsted and Lewis acidic sites, is expected to be a useful solvent and catalyst for organic reactions.

Electrochromic Devices Based on Poly(2,6-di(9H-carbazol-9-yl)pyridine)-Type Polymer Films and PEDOT-PSS.

2,6-Di(9H-carbazol-9-yl)pyridine (DiCP) was synthesized and its corresponding homopolymer (PDiCP) and copolymers (P(DiCP-co-CPDT), P(DiCP-co-CPDT2), P(DiCP-co-CPDTK), and P(DiCP-co-CPDTK2)) were synthesized electrochemically. The anodic copolymer with DiCP:cyclopentadithiophene ketone (CPDTK) = 1:1 feed molar ratio showed high transmittance change (ΔT%) and colouration efficiency (η), which were measured as 39.5% and 184.1 cm² C-1 at 1037 nm, respectively. Electrochromic devices (ECDs) were composed of PDiCP, P(DiCP-co-CPDT), P(DiCP-co-CPDT2), P(DiCP-co-CPDTK), and P(DiCP-co-CPDTK2) as anodically-colouring polymers, and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS) as cathodically-colouring polymers. P(DiCP-co-CPDTK)/PEDOT-PSS ECD showed light silverish-yellow at 0.0 V, light grey at 0.7 V, grey at 1.3 V, light greyish blue at 1.7 V, and greyish blue at 2.0 V. Moreover, P(DiCP-co-CPDTK)/PEDOT-PSS ECD presented high ΔT (38.2%) and high η (633.8 cm² C-1) at 635 nm.

Three Carbazole-Based Polymers as Potential Anodically Coloring Materials for High-Contrast Electrochromic Devices.

Three carbazole-based conjugated polymers (poly(3,6-di(2-thienyl)carbazole) (PDTC), poly(2,7-bis(carbazol-9-yl)-9,9-spirobifluorene) (PS2CBP), and poly(3,6-bis(N-carbazole)-N-ethylcarbazole) (PCEC)) are synthesized using electrochemical polymerization. The spectroelectrochemical studies indicate that the PDTC, PS2CBP, and PCEC films show reversible electrochromic behaviors in their redox states, and the PS2CBP film shows a distinct color transition with four various colors (gray at 0 V, grayish-green at 1.0 V, moss green at 1.2 V, and foliage green at 1.4 V). The maximum optical contrast of the PS2CBP and PCEC films is 39.83% at 428 nm and 32.41% at 420 nm, respectively, in an ionic liquid solution. Dual-type electrochromic devices (ECDs) that employ PDTC, PS2CBP, or PCEC film as an anodic layer, and PProDOT-Et2 film as a cathodic layer, were constructed. The as-prepared PCEC/PProDOT-Et2 ECD shows high optical contrast (38.25% at 586 nm) and high coloration efficiency (369.85 cm² C-1 at 586 nm), and the PS2CBP/PProDOT-Et2 ECD shows high optical contrast (34.45% at 590 nm), good optical memory, and good long-term cycling stability.

Applications of Three Dithienylpyrroles-Based Electrochromic Polymers in High-Contrast Electrochromic Devices.

Three dithienylpyrroles (1-(4-(methylthio)phenyl)-2,5-di(thiophen-2-yl)-pyrrole (MPS), 1-(4-methoxyphenyl)-2,5-di(thiophen-2-yl)-pyrrole (MPO), and 4-(2,5-di(thiophen-2-yl)-pyrrol-1-yl)benzonitrile (ANIL)) were synthesized and their corresponding polydithienylpyrroles (PSNS) were electrosynthesized using electrochemical polymerization. Spectroelectrochemical studies indicated that poly(1-(4-(methylthio)phenyl)-2,5-di(thiophen-2-yl)-pyrrole) (PMPS) film was green, dark green, and brown in the neutral, oxidation, and highly oxidized state, respectively. The incorporation of a MPS unit into the PSNS backbone gave rise to a darker color than those of the MPO and ANIL units in the highly oxidized state. The PMPS film showed higher ΔTmax (54.47% at 940 nm) than those of the PMPO (43.87% at 890 nm) and PANIL (44.63% at 950 nm) films in an ionic liquid solution. Electrochromic devices (ECDs) employing PMPS, PMPO, and PANIL as anodic layers and poly(3,4-(2,2-diethypropylenedioxy)thiophene)(PProDOT-Et2) as a cathodic layer were constructed. PMPO/PProDOT-Et2 ECD showed the highest ΔTmax (41.13%) and coloration efficiency (674.67 cm²·C-¹) at 626 nm, whereas PMPS/PProDOT-Et2 ECD displayed satisfactory ΔTmax (32.51%) and coloration efficiency (637.25 cm²·C-¹) at 590 nm. Repeated cyclic voltammograms of PMPS/PProDOT-Et2, PMPO/PProDOT-Et2, and PANIL/PProDOT-Et2 ECDs indicated that ECDs had satisfactory redox stability.