Polymerization Of EDOT Research Articles

Chiral Liquid‐Crystalline Ionic Liquid Systems Useful for Electrochemical Polymerization that Affords Helical Conjugated Polymers

AbstractIonic liquids bearing both liquid crystallinity and chirality are potentially applicable for chiral electrochemical syntheses and polymerizations. In this study, two types of chiral nematic liquid‐crystalline ionic liquids (N*‐LCILs) are developed to achieve asymmetric electrochemical polymerization without a supporting electrolyte and even a chiral dopant. N*‐LCILs are prepared i) by adding an axially chiral binaphthyl derivative as an external chiral dopant to imidazolium cation–based LCILs or ii) by incorporating a chiral binaphthyl phosphate as a counter anion in LCILs. Helical poly(3,4‐ethylenedioxythiophene) (H‐PEDOT) films are successfully synthesized through electrochemical polymerization of a dimer‐ or trimer‐type 3,4‐ethylenedioxythiophene (EDOT) monomer in an N*‐LCIL, where N*‐LCIL plays the role of both an asymmetric solvent and a supporting electrolyte. H‐PEDOT films have helically π‐stacked structures of conjugated chains and spiral morphologies consisting of one‐handed screwed fibril bundles. The plausible mechanism of the asymmetric electrochemical polymerization of EDOT in N*‐LCIL is proposed to elucidate the correlation of helical sense between the helically π‐stacked chains, screwed fibril bundles, and N*‐LCIL. The two present types of N*‐LCILs are the first to enable supporting electrolyte–free asymmetric electrochemical polymerization, and they have potential applications in various types of chiral electrochemical syntheses, expanding the potential utility of ionic liquids.

Formulation of PEDOT:S-Graphene Hybrid and Its Application as Transparent Conducting Electrode Materials

Novel chemically reduced graphene oxide/poly(vinyl sulfate) (rGO/PVS) assembly has been simply prepared by noncovalent method. Polymerization of EDOT on rGO/PVS assembly (S-Graphene) produced rGO/PVS/PEDOT hybrid (PEDOT:S-Graphene). Transparent conducting electrodes (TECs) based on PEDOT:S-Graphene revealed higher electrical conductivity together with higher optical transparency and colorlessness compared with TCEs based on the traditional PEDOT:PSS. Both high dispersion stability and ultrathin morphology of S-Graphene and PEDOT:S-Graphene contributes to the synergistic TCE performance enhancement through the coexistence of electrically conducting PEDOT and rGO in the hybrid TEC materials.

Flexible printed humidity sensor based on poly(3,4-ethylenedioxythiophene)/reduced graphene oxide/Au nanoparticles with high performance

Wearable and flexible humidity-sensing devices are essential for the real-time monitoring of air humidity in health and environmental applications. We propose a flexible sensor based on a conductive polymer comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and reduced graphene oxide(rGO) to monitor changes in humidity. GO was used as a hard template for the in situ polymerization of EDOT to obtain PEDOT:rGO. Then, PEDOT:rGO-PEI/Au nanoparticles (NPs) ink was prepared through the in situ reduction of Au NPs modified with polyethylenimine (PEI). The ink was printed on the surface of a hydrophilic modified polyethylene terephthalate (PET) substrate using an ink-jet printer to form a specific pattern. After assembly, a PET-based PEDOT:rGO-PEI/Au NPs (PrGANPs) sensor device with high electrical performance, transparency, and sensitivity was obtained for testing at a variety of RH levels. The prepared PET-based PrGANPs sensor printed with 50 layers had a transmittance up to 61% at 500 nm. And the response and recovery times were approximately 20 and 35 s at 98% RH, respectively. Stability was maintained even after bending 200 times, and the sensor could respond within the humidity range of 11%–98% RH, while in response to a wide resistance range of 7.41%–51.60%.

An investigation on the fabrication of conductive polyethylene dioxythiophene (PEDOT) nanofibers through electrospinning

This article reports on the possibility of the fabrication of conductive PEDOT (3,4 poly ethylene dioxythiophene) nanofibers through electrospinning. Electrospinning of pure PEDOT nanofibers from its solution has not yet become possible. Also in this work, the efforts to electrospin pure PEDOT or pure EDOT nanofibers proved fruitless. Hence, poly(acrylic acid) (PAA)was employed to assist the electrospinning of EDOT. EDOT:PAA nanofibers were collected in an oxidation bath, where in-situ polymerization of EDOT into PEDOT occurred. After a series of experiments, PEDOT/PAA (50:50) and PEDOT/PAA (67:33) nanofibers were successfully fabricated. The lowest average diameter of the PEDOT/PAA nanofibers was around 300 nm. An electrical conductivity of 0.16 S/cm was recorded for the PEDOT/PAA (50:50) nanofibrous web which is a considerable improvement over similar products reported in the literature. X-ray analysis showed that PEDOT/PAA nanofibers have an amorphous microstructure. FTIR analysis showed no reaction or major interactions between EDOT or PEDOT and PAA. Moreover, FTIR analysis proved successful polymerization of EDOT into PEDOT. TEM images indicated a good degree of homogeneity for PEDOT and PAA in PEDOT:PAA nanofibers.

Conductive HNTs-PEDOT hybrid preparation and its application in enhancing the dielectric permittivity of HNTs-PEDOT/PVDF composites

A novel flexible dielectric composite with halloysite nanotube-poly(3,4-ethylenedioxythiophene) (HNTs-PEDOT) hybrid as conductive filler and poly(vinylidene fluoride) (PVDF) as polymer matrix were prepared via a blending and hot-pressing technique. HNTs-PEDOT hybrid, with PEDOT coated onto both the negatively charged inner and out surfaces of the HNTs tubes, were fabricated by chemical oxidative polymerization of EDOT with unmodified HNTs as templates. The conductivity of HNTs-PEDOT hybrid with 50 wt% HNTs is up to 12.89 S/cm, which is 100 times greater than that of pure PEDOT (about 0.12 S/cm) synthesized under the similar condition. With PEODT as outside organic layer, HNTs-PEDOT could be easily dispersed in PVDF matrix uniformly. In addition, with the introduction of HNTs-PEDOT into PVDF matrix, it makes a phase transformation of PVDF from α to electroactive β phase. HNTs-PEDOT/PVDF shows good dielectric performance. At close to the percolation threshold value (fHNTs-PEDOT = 0.11), the dielectric constant of HNTs-PEDOT/PVDF is up to 641 at 1000 Hz, which is attractive to prepare flexible materials.

Electrode materials for electrochemical capacitors based on poly(3,4 ethylenedioxythiophene) and functionalized multi-walled carbon nanotubes characterized in aqueous and aprotic electrolytes

Within this work, we report a facile one-stage synthesis of nanocomposites based on functionalized carbon nanotubes (CNTs) and electroactive polymer poly(3,4-ethylenedioxythiophene). Three different composites are investigated as potential electrode materials for the electrochemical capacitors. Two of the composites contain carbon nanotubes (ox-CNTs), functionalized by acid oxidation process (65% HNO3, 120 °C). The third composite comprises of non-covalently functionalized carbon nanotubes, modified by surfactant addition. The functionalization process provides a uniform distribution of carbon nanotubes in water, what in turn helps to synthesize homogenous and reproducible composite materials. The composites are synthesized by chemical polymerization of EDOT in the solution of dispersed carbon nanotubes. The goal of such synthesis is to obtain polymer chains directly on CNTs. For comparison, one composite is prepared by simple dispersion of ox-CNTs in the commercially available pEDOT/polystyrene sulfonate (PSS) solution. The composite layers are tested electrochemically in aqueous and aprotic electrolytes for electrochemical capacitor application. The electrochemical results reveal that the presence of oxidized carbon nanotubes improves the conductivity and increases the capacitance values of the composites layers. The best electrochemical performance (capacitance of approx. 80 F g−1 in the aqueous and aprotic electrolyte) is exhibited by the composite obtained by chemical polymerization of EDOT in the solution of ox-CNTs.

RAFT Polymerization of an Intrinsically Stretchable Water-Soluble Block Copolymer Scaffold for PEDOT.

Despite the common association of π-conjugated polymers with flexible and stretchable electronics, these materials can be rigid and brittle unless they are designed otherwise. For example, low modulus, high extensibility, and high toughness are treated as prerequisites for integration with soft and biological structures. One of the most successful and commercially available organic electronic materials is the conductive and brittle polyelectrolyte complex poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). To make this material stretchable, additives such as ionic liquids must be used. These additives may render the composite incompatible with biological tissue. In this work, we describe the synthesis of an intrinsically stretchable variant of the conductive polymer PEDOT:PSS that is free of additives. The approach involves the synthesis of a block copolymer comprising soft segments of poly(polyethylene glycol methyl ether acrylate) (PPEGMEA) and hard segments of poly(styrene sulfonate) (PSS) using a reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequently, we used the newly synthesized ionic elastomer PSS-b-PPEGMEA as a matrix for the oxidative polymerization of EDOT. The resulting polyelectrolyte elastomer, PEDOT:PSS-b-PPEGMEA, can withstand elongations up to 128% and has a toughness up to 10.1 MJ m-3. While the polyelectrolyte elastomer is not as conductive as the commercial material, the toughness and extensibility are each more than an order of magnitude higher. Moreover, the electrical conductivity of the polyelectrolyte elastomer exhibits minimal decrease with strain within the elastic regime. We then compared the block copolymer to physical blends of PEDOT:PSS and PPEGMEA. The blend material had a much lower failure strain of only 38% and a maximum toughness of 4.9 MJ m-3. This approach thus emphasizes the importance of the covalent linking of the PSS and PPEGMEA blocks. Furthermore, we demonstrate that the conductivity of scratched films can be restored upon exposure to water.

P-Toluenesulfonic acid catalytic polymerization of EDOT without oxidants

In this paper, a convenient oxidants free acid polymerization method is developed to synthesize poly(3,4-ethylenedioxythiophene) (PEDOT). p-Toluenesulfonic acid (p-TsOH) is served as catalyst to direct polymerization of EDOT. The electron spin resonance spectra revealed that EDOT was protonated into radical species under p-TsOH. As-obtained PEDOT has a highest average degree of polymerization of 11.3 and the structure details are characterized by 1H NMR, GPC and FTIR. An acid promoted EDOT protonation polymerization mechanism is proposed and clarified.

The promoting effect on pre-osteoblast growth under electrical and magnetic double stimulation based on PEDOT/Fe3O4/PLGA magnetic-conductive bi-functional scaffolds.

Electrical stimulation (ES) and magnetic stimulation (MS) can promote bone tissue formation in vivo. Loading ES and MS simultaneously would be very beneficial for bone tissue construction in vitro or in vivo. Magnetic-conductive bi-functional scaffolds which are favorable for the transfer of ES and MS, could further facilitate bone cell/tissue growth. Poly(3,4-ethylenedioxythiophene) (PEDOT)/Fe3O4/polylactic acid-co-glycolic acid (PLGA) magnetic-conductive bi-functional fibrous scaffolds were prepared through in situ polymerization of EDOT on Fe3O4/PLGA fibers. MC3T3-E1 pre-osteoblasts were incubated on the PEDOT/Fe3O4/PLGA fibrous scaffolds and were stimulated by electrical, magnetic and electrical-magnetic signals respectively to detect the impact of different stimulation on cell viability. The measured results show that the scaffolds possess good conductivity and superparamagnetic responsiveness. Furthermore, both electrical and magnetic stimulation promoted cell proliferation and magnetic stimulation could induce cell alignment arrangement. Meanwhile, under electrical-magnetic double stimulation, cell viability was much higher than for cells under single electrical or magnetic stimulation. The growth promoting effects of PEDOT/Fe3O4/PLGA fibrous scaffolds under electrical-magnetic double stimulation has great practical potential for bone tissue engineering.

Study on Fabricating PEDOT Electrodes by Liquid Phase Depositional Polymerization of EDOT and Direct Patterning with 172 nm Vacuum Ultraviolet Radiation

The transparent electrode made of conventional flexible transparent conductive film (FTCF) exhibits poor fatigue lifetime due to its brittle indium–tin oxide (ITO) coating. To develop an ITO-free flexible transparent electrode, a poly(ethylene phthalate) (PET) film with a ferric p-toluene-sulfonate (Fe(OTs)3) coating was immersed in 3,4-ethylenedioxythiophene (EDOT) solution for synthesizing poly(3,4-ethylenedioxythiophene) (PEDOT) coating in situ and irradiated with 172 nm VUV through a mask for creating conductive patterns. The sheet resistance and transmittance of the films were measured with four-point probe and spectrophotometer. The conjugative structure and doping level of the synthesized PEDOT coatings were analyzed with UV–vis spectroscope and X-ray photoelectron spectroscope. The effects of processing conditions on the microscopic structures and optoelectronic properties of the coatings were studied. A conductive PEDOT coating formed as a PET film with an Fe(OTs)3 coating was suspended in an EDO...

Improvement of optical properties and redox stability of poly(3,4-ethylenedioxythiophene)

In order to improve the optical properties and redox stability of poly(3,4-ethylenedioxythiophene) (PEDOT) without changing its electrochemical and electrochromic behaviour, it was supported with alkyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage. The corresponding copolymers were obtained electrochemically via potentiostatic or potentiodynamic methods and compared to the parent homopolymers. Electrochemical polymerization of EDOT and POSS containing EDOT called EDOT-POSS in various monomer feed ratios was performed in an electrolyte solution of 0.1 M TBAPF6 dissolved in a mixture of dichloromethane and acetonitrile (1/3: v/v). Just as PEDOT, the copolymers represented the similar band gap (1.61 eV), redox and electrochromic behaviors. On the other hand, when compared to the parent PEDOT, the presence of POSS cages in the copolymer backbone improved the redox stability and optical properties of PEDOT such as higher percent transmittance change (65% at 621 nm), higher transparency at oxidized state, lower switching time (∼1.0 s) and higher coloration efficiency (463 cm2/C for 95% switching) as well as higher electrochemical stability (86% of its electroactivity retains after 1750 cycles under ambient conditions).

Synthesis of HNTs@PEDOT composites via in situ chemical oxidative polymerization and their application in electrode materials

The hybrid composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and halloysite nanotubes (HNTs) was synthesized by a two-step process. First, poly(sodium styrene sulfonate) (PSSNa) was grafted onto HNTs via surface initiated atom transfer radical polymerization. Then with the HNTs-g-PSS as a template and the grafted PSS chains as the counterion dopant, PEDOT was precipitated onto the template via in situ oxidization polymerization of EDOT to form HNTs@PEDOT hybrid composites. The conductivity of HNTs@PEDOT can reach up to 9.35S/cm with the content of 40% HNTs-g-PSS, which increased almost 78 times than that of pure PEDOT (about 0.12S/cm) prepared at the similar condition. Further treated with p-toluenesulfonic acid (TsOH) as external dopant, the conductivity of HNTs@PEDOT increased to 24.3S/cm. The electrochemical properties of the composites were investigated with cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy with three-electrode cell configuration. The results showed that the capacitance of HNTs@PEDOT composite increased 55% than that of pure PEDOT.

Charge transfer induced polymerization of EDOT confined between 2D titanium carbide layers

In situpolymerization of 3,4-ethylenedioxythiophene (EDOT) is achieved on the surface of 2D Ti3C2TxMXene without using any oxidant, resulting in improved lithium ion storage capability of Ti3C2Tx/poly-EDOT hybrids.

Vapor-Phase Polymerized Poly(3,4-Ethylenedioxythiophene) on a Nickel Nanowire Array Film: Aqueous Symmetrical Pseudocapacitors with Superior Performance.

Three-dimensional (3D) nanometal scaffolds have gained considerable attention recently because of their promising application in high-performance supercapacitors compared with plain metal foils. Here, a highly oriented nickel (Ni) nanowire array (NNA) film was prepared via a simple magnetic-field-driven aqueous solution deposition process and then used as the electrode scaffold for the vapor-phase polymerization of 3,4-ethylenedioxythiophene (EDOT). Benefiting from the unique 3D open porous structure of the NNA that provided a highly conductive and oriented backbone for facile electron transfer and fast ion diffusion, the as-obtained poly(3,4-ethylenedioxythiophene) (PEDOT) exhibited an ultra-long cycle life (95.7% retention of specific capacitance after 20 000 charge/discharge cycles at 5 A/g) and superior capacitive performance. Furthermore, two electrodes were fabricated into an aqueous symmetric supercapacitor, which delivered a high energy density (30.38 Wh/kg at 529.49 W/kg) and superior long-term cycle ability (13.8% loss of capacity after 20 000 cycles). Based on these results, the vapor-phase polymerization of EDOT on metal nanowire array current collectors has great potential for use in supercapacitors with enhanced performance.

EDOT polymerization at photolithographically patterned functionalized graphene

Graphene possesses unique features that make it attractive for nanotechnology. Functional devices often require combination of several materials with specific functions, and graphene-polymer composites are one of them. Herein, we report on the preparation of PEDOT:Graphene bilayers by in situ polymerization of EDOT on covalently functionalized graphene. The polymerization proceeds exclusively on the grafted graphene, and patterned structures with high spatial resolution down to 3 μm could have been prepared. The composite exhibits enhanced efficiency of electrochemical doping compared to pristine graphene, asymmetrical transport characteristic with improved hole-transporting properties and efficient electronic communication between the two materials.

Preparation of Pt@Cu Core-Shell Particles Incorporated in Poly-(3,4-ethylenedioxythiophene) for Catalytic Applications

Hybrid materials offer the possibility to combine advantageous properties of the individual components. In the macroscopic world adobe or reinforced concrete are well known examples. The same principle can also be applied to electrodes for electro-catalytic reactions. The usually precious metal catalyst like Pt for fuel cells (or Au for sensors) is reduced in size (and thus in costs) to smaller and smaller particles which are bonded to supporting surfaces. An interesting approach is to prepare a porous matrix in which these catalytic particles can be homogeneously incorporated. Promising candidates are conducting polymers like poly-(3,4-ethylenedioxythiophene) (PEDOT) whose structure can be tuned by the used electrolyte and/or the supporting electrolyte. To homogeneously incorporate the particles they should be prepared in situ with the polymer which is possible by cyclic voltammetry or (reversed) pulse methods. As Pt2+ has the possibility to oxidize EDOT directly we deposited Cu as an intermediate with the polymer by cyclic voltammetry. In a second step a chemical exchange reaction was performed using a Pt4+containing solution. This approach can yield Pt@Cu core shell particles embedded in a polymer matrix. A positive effect of this is also that the electronic structure of the Pt layer is modified by the underlying Cu core which can lead to enhanced catalytic activities. The cyclic voltammograms of the preparation of PEDOT/Cu films show a superposition of PEDOT and Cu features. At potentials more positive than ca. 0.9 V vs. Ag/AgCl sat. KCl polymerization of EDOT occurs while at more negative potentials the capacitive behaviour of the PEDOT film dominates next to the Cu redox waves at ca. 50 mV. SEM/EDX analyses showed that thus prepared films contain 10 to 17 wt% Cu depending on the switch-off potential. If the preparation stopped before Cu oxidation Cu crystallites could be observed on the PEDOT surface and the Cu content was higher. In the case of well oxidized films no distinct Cu centres could be found (see figure 1). The chemical exchange reaction with Pt was monitored by a quartz crystal microbalance (QCM). According to QCM data the deposited mass of Pt corresponds to ca. 60 monolayers on the geometric area. This contribution will discuss the preparation of the PEDOT/Pt@Cu hybrid films as well as the electrochemical and mechanical characterization of these films. This will include CV and impedance (EIS) data as well as QCM data. Fig. 1. SEM images of a PEDOT/Cu film with the preparation stopped at potentials negative to the Cu redox potential. (left) top view of the surface and (right) FIB cross section. Figure 1

Electrochemical polymerization of EDOT modified Phthalocyanines and their applications as electrochromic materials with green coloration, and strong absorption in the Near-IR

Electropolymerization by cyclic voltammetry of both Cu and Zn EDOT modified phthalocyanines is described. Polymeric films were successfully formed on Pt, ITO, and Pt containing a previously deposited layer of PEDOT. Based on electrochemical and spectroelectrochemical studies, a possible polymerization mechanism and a polymer structure are proposed. The films showed a green coloration in the reduced state and a grey coloration and also a very broad band that extends to the NIR zone in the fully oxidized state. Optical contrast ratios of 24% at 650nm, and of 60% at 1050nm were achieved, with very fast switching times. A window-type device was also constructed, demonstrating the possible applications of these electrochromic materials in smart windows, which could help in the control of light in the visible and in the control of heat flux because of their strong absorption in the NIR range.

In-situ synthesis of transparent conductive PEDOT coating on PET foil by liquid phase depositional polymerization of EDOT

To prepare FTCF, PET film was dipped in Fe(OTs)3n-butanol solution for Fe(OTs)3 adsorption and suspended in EDOT cyclohexane solution for EDOT depositional polymerization. The adsorbed Fe(OTs)3 were determined with idometry and the synthesized PEDOT coating were characterised with FTIR and UV–vis spectroscopes. The sheet resistance and transmittance of synthesized PEDOT/PET films were measured with four-point probe and spectrophotometer. The effect of Fe(OTs)3 drying time and polymerization time on sheet resistance and transmittance were investigated. From 80mmol/L of Fe(OTs)3 solution, PET film could adsorb Fe(OTs)3 at a magnitude of 1.7mmol/m2. As PET with adsorbed Fe(OTs)3 was suspended in EDOT solution, EDOT monomers deposited to PET surface and joined one another to form positive charged PEDOT molecules continually, resulting in transparent and conductive PEDOT coating on PET film. After dipped in 80mmol/L Fe(OTs)3 solution, dried at temperature 40°C and suspended in 80mmol/L EDOT solution for 15h, PEDOT coating with thickness about 100nm and conductivity 530S/cm generated; flexible PEDOT/PET films with transmittance above 80% and sheet resistance below 200Ω/area were produced.

A scalable route to prepare core–shell structured ZnO@PEDOT nanowires and PEDOT nanotubes and their properties as electrode materials

A composite of a core–shell structured nanowires with ZnO as a core and conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as a shell was prepared. At first, the hexagonal ZnO nanowires, with diameter of about 80–100nm and length 4–5μm, were fabricated by hydrothermal synthesis process. Then a thick layer of poly(trifluoroethyl methacrylate)-block-poly(sodium styrene sulfonate) (PTFEMA-b-PSSNa) was grafted from the surface of ZnO nanowires via atom transfer free radical polymerization. At last, with the ZnO@PTFEMA-b-PSSNa as a template and the PSSNa chain as the counterion dopant, PEDOT was precipitated onto the surface of the template to form the composite of ZnO@PEDOT/PSSNa. With the evaluation of the EDOT polymerization, the thickness of the PEDOT layer increased steadily. However, as the ratio of EDOT/ZnO was greater than 1:2, the ZnO nanowires templates were dissolved at last and then PEDOT particles were produced due to increasing of the acidity during the oxidation polymerization of EDOT. In this case, the product was the mixture of the nanotubes and particles of PEDOT/PPSNa. The electrochemical capacitances of the composites with different structures were investigated with cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques with three-electrode cell configuration. The maximum specific capacitance of ZnO@PEDOT electrode can reach 101.34F/g at 20mV/s.

Nanostructured Semiconducting PEDOT–TiO2/ZnO Hybrid Composites for Nanodevice Applications

In this paper, we have developed a simple strategy for the preparation of hybrid nanocomposites of poly(3,4-ethylenedioxythiophene)–TiO2/ZnO (PZT) and demonstrated its application in a thermoelectric device. Hierarchical hetero-nanostructured TiO2/ZnO (ZTO) was prepared by a facile sol–gel process in the presence of a biocapping agent. PZT was prepared by in situ polymerization of EDOT in the presence of ZTO. It was characterized by UV–visible, FT-IR, XRD, Raman, SEM, TEM, and AFM analyses. Results revealed homogeneous distribution of ZTO with a heterocrystalline phase of wurtzite ZnO/anatase TiO2 having high density of various defects in the hybrid nanocomposite. Studies showed that ZTO is excellently interfaced with highly ordered self-assembled extended π-layers of PEDOT chains, which could enhance the charge carrier concentration (3.92 × 1020 cm–3) and charge carrier mobility (0.83 cm2 V–1 s–1). Furthermore, we have demonstrated its application as a thermoelectric material by fabricating the device (C...