Polythiophene Polymer Research Articles

Polythiophene nanofibril bundles surface-embedded in elastomer: a route to a highly stretchable active channel layer.

A stretchable polymer channel layer for organic field-effect transistors is obtained by spin-coating a blend solution of polythiophene and rubber polymer. A network of the polythiophene nanofibril bundles surface-embedded in the rubber matrix allows large stretchability of the polythiophene film layer.

A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

This report comprises the novel usage of polythiophene – ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett–Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box–Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002–0.667ngmL−1. Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues.

Non-covalent stabilization and functionalization of boron nitride nanosheets (BNNSs) by organic polymers: formation of complex BNNSs-containing structures

The straightforward non-covalent functionalization and solubilization of hexagonal boron nitride nanosheets (BNNSs) has been achieved by reacting either polythiophene or polyvinylpyrrolidone polymers with exfoliated BNNSs. The BNNSs apparently form strong π–π stacking interactions with the polymers to yield stable derivatized nanosheets with modified properties. A number of polythiophene polymers functionalized with carboxylic acid groups that are connected to the thiophene subunit by varying numbers of CH2-hydrocarbon linker units have also been tethered to the exfoliated BNNSs. These BNNS–polythiophene–(CH2)n–COOH structures have been further coordinated to pre-formed TiO2 nanoparticles to form more complex BNNS–polythiophene–(CH2)n–COO–TiO2 hybrid nanomaterials through covalent binding between the TiO2 nanoparticle surface and the carboxylic acid functional group of the BNNS–polythiophene unit. These novel structures have been characterized by SEM, TEM, FTIR, UV–Vis, and other spectroscopic data.

Carbon Nanotube Networks: Nano‐Engineering of SWNT Networks for Enhanced Charge Transport at Ultralow Nanotube Loading (Adv. Mater. 19/2014)

Arrays of nano-engineered carbon nanotube networks embedded in nanoscale polymer structures enable highly efficient charge transport as demonstrated by D. R. Barbero and co-workers on page 3111. An increase in charge transport by several orders of magnitude is recorded at low nanotube loading compared to traditional random networks in either insulating (polystyrene) or semiconducting (polythiophene) polymers. These novel networks are expected to enhance the performance of next generation hybrid and carbon based photovoltaic devices.

Nano‐Engineering of SWNT Networks for Enhanced Charge Transport at Ultralow Nanotube Loading

We demonstrate a simple and controllable method to form periodic arrays of highly conductive nano-engineered single wall carbon nanotube networks from solution. These networks increase the conductivity of a polymer composite by as much as eight orders of magnitude compared to a traditional random network. These nano-engineered networks are demonstrated in both polystyrene and polythiophene polymers.

Enzymatic polymerization of polythiophene by immobilized glucose oxidase

In this study ‘green’, environmentally friendly enzymatic reaction-based synthesis of conducting polymer polythiophene (PTP) is proposed. Glucose oxidase (GOx) was shown as an effective catalyst, which, in the presence of glucose, produces hydrogen peroxide suitable for the oxidative polymerization of PTP under ambient conditions at neutral pH. Enzymatically induced formation of the PTP layer over GOx-modified graphite rod electrode (GRE) was demonstrated and evaluated amperometrically and by attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy. Surface morphology of GOx- and PTP-modified GR electrodes was characterized by atomic force microscopy. It was clearly shown that the apparent kinetic Michaelis constant (KM(app.)) of GOx/PTP-modified GRE increased by increasing the duration of polymerization reaction. Therefore, enzymatic polymerization could be applied in adjustment and/or tuning of KM(app.) and other kinetic parameters of GOx-based electrodes used in biosensor design.

Applications of conjugated polymer based composites in wastewater purification

This review describes the application of conjugated polymer (polyaniline, polypyrrole, and polythiophene) based composites in wastewater purification.

Ion Transport and Switching Speed in Redox-Gated 3-Terminal Organic Memory Devices

The dynamics of redox gated organic memory devices based on dynamic doping of polythiophene were examined in detail in order to improve “write” and “erase” speed and determine ultimate performance. A 3-terminal geometry similar to a field effect transistor provided a source/gate circuit which reversibly oxidized a polythiophene polymer to cause a large increase in conductance between the source and drain electrodes. The devices were cycled for >1000 complete R/W/R/E cycles, and operated at relatively low voltage compared to commercial “flash” memory. The “write” and “erase” speeds were improved by a factor of >100 by using a spin-coated electrolyte layer and by small increases in device temperature. The influence of charging current and polaron propagation on response time were determined to be minor, with the rate limiting process being identified as the rate of conducting polaron generation. The main factor determining the W/E time was the mobility of ions in the polyethylene oxide electrolyte layer, which resulted in resistance losses during the application of the S-G “write” pulse. Response time was strongly dependent on the atmosphere, with water or acetonitrile vapor significantly increasing the rate of polaron generation. The results are important for design of molecular memory devices based on dynamic doping, and indicate likely avenues for further performance improvements.

In situ polymerizations of thiophene on TiO2 films using the semiconductors as initiators

ABSTRACTIn this work, we prepare the TiO2 nanoparticle film and anatase TiO2 nanoarray film, and we achieve the polymerizations of thiophene using the photoexcited TiO2 film as the initiators. It is measured that the in situ polymerizations of thiophene take place on the surfaces of the two films. The growth of polythiophene (PTh) on the TiO2 nanoarray is monitored using Fourier‐transform Raman spectroscopy. The TiO2 nanoarray is found to strongly interact with the PTh polymers. It is observed using scanning electron microscope that the microspores in the nanoarray are filled by the polymers after the reaction of 3 h, and the nanoarray is fully covered by the polymer layer when the polymerization lasts for 5 h. The PTh–TiO2 nanoarray composite films are measured for the transient photocurrents and photocurrent‐voltage characteristics. The dependence of the photocurrents on the reaction time is revealed and discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40187.

Polymer dots for quantifying the total hydrophobic pathogenic lysates in a single drop

A selective, rapid, small sample load (2–4μL), and sensitive quantification method for the hydrophobic cellular biomolecules of pathogenic bacteria and their biosensing application were reported. The present approach is based on using polythiophene polymer dots (2.5nm), which were prepared via the oxidation/polymerization reactions and then were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), ultraviolet spectroscopy (UV), and matrix (surface) assisted laser desorption/ionization mass spectrometry (M(S)ALDI-MS). The present method requires only gentle agitation for a single drop of aqueous bacteria suspension (10μL, Pseudomonas aeruginosa (1×104cfu/mL) and Staphylococcus aureus (1×105cfu/mL)) with 1mL of polythiophene (0.5mg/mL) in chloroform, and the time required for quantifying the total hydrophobic was significantly reduced to less than 3min. The polythiophene polymer dots is also a quantitative assessment of bacteria for aqueous and blood samples if exposed to more than 4–5μL of pathogenic bacteria and thus, it is a new biosensor for quantitative hydrophobic portions. The fluorescence intensity of polythiophene was enhanced after adding different volumes of pathogenic bacteria with low colony units. The standard bacteria suspensions of P. aeruginosa and S. aureus have low LOD (limits of detection) for 2μL (1×104cfu/mL) and 4μL (1×105cfu/mL), respectively. Further, the pathogenic bacteria were spiked into mouse blood and the total hydrophobic biomolecules were quantified. This method is extremely rapid as it does not require any culture steps prior to analysis and also no need for any separation or post sample treatments.

Evaluation of Solid or Liquid Phase Conducting Polymers Within a Flexible Textile Electrochromic Device

Conducting polymers, in both their solid or liquid states, have been successfully employed within a novel flexible 4-layer electrochromic prototype device. The device consists of the polymer combined with a flexible PET textile spacer, sandwiched between two electrodes - one of which is applied on a flexible textile substrate. The electrochromic materials that have been employed are polyaniline and substituted polythiophene polymers. Two methods of preparation have been used. Aniline was chemically polymerized to the surface of the PET textile substrate, in its solid state, prior to application within the device. Conversely, substituted thiophene monomers, in the solution phase, were suspended within the textile spacer and electrochemically polymerized in situ within the device. The application of an electrical voltage ( ±3 V) effects a reversible color change for both solid and liquid phase systems, providing a flexible communicative textile with applications for protection and safety purposes, or for added fashion. This paper outlines the preparation and characterization of each of the solid and liquid electrochromic display systems and discusses the benefits and drawbacks of each.

Electrooptical Spectroscopy of Uniaxially Aligned Polythiophene Films in Field-Effect Transistors

Charge carriers induced in field-effect transistors based on a uniaxially aligned polythiophene polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), are investigated by electrooptical charge modulation spectroscopy (CMS). We used a zone-casting deposition method for uniaxial alignment of the nanoribbon crystalline domains of the polymer and examined the optical anisotropy of neutral and charge induced absorptions in FETs. We find that the charge-induced optical absorptions of the polaronic carriers at the interface exhibit a similar degree of uniaxial anisotropy as the absorption spectrum of the neutral polymer bulk suggesting similar degree of polymer alignment at the interface compared with the bulk. We observe subtle differences in the spectral shape of the polaron absorption polarized along and perpendicular to the polymer chain direction. We also detect an additional charge-induced absorption peak appearing at high charge carrier concentrations, which is similar to the charge-induced absorption that is typical for chemically doped films. These observations provide important insight into the interplay between polaron transport and polymer microstructure.

Plasma Nanocoating of Thiophene onto TiO2 Nanoparticles

TiO2 nanoparticles were coated uniformly, with a controllable thickness of conductive polymer polythiophene, in a rotating capacitively coupled radio-frequency (RF) plasma reactor. Plasma parameters such as power, pressure, and time affected the properties of the TiO2/polythiophene nanocomposites, and plasma characteristics were examined using an optical monochromator, as well as in situ residual gas analysis (RGA), Fourier transform infrared (FTIR), X-ray, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and four-probe techniques. The plasma optical emission results showed that the peaks from TiO2 decreased by time as the polythiophene coating thickness increases. TEM results confirmed the polythiphene coating onto TiO2 in order of nanometers. It was obtained data from main peaks (molecular masses of 2 (H2), 18 (H2O), 28 (C2H6), and C2H4) of mass spectra recorded by RGA. The shift and the changes in the intensity of the FTIR peaks are credited to the substantive internalization b...

Exploiting Core–Shell Synergy for Nanosynthesis and Mechanistic Investigation

The core-shell nanoparticle structure, which consists of an inner layer "guest" nanoparticle encapsulated inside another of a different material, is the simplest motif in two-component systems. In comparison to the conventional single-component systems, complex systems pose both challenges and opportunities. In this Account, we describe our recent progresses in using core-shell motif for exploring new and sophisticated nanostructures. Our discussion is focused on the mechanistic details, in order to facilitate rational design in future studies. We believe that systematic development of synthetic capability, particularly in complex and multifunctional systems, is of great importance for future applications. A key issue in obtaining core-shell nanostructures is minimizing the core-shell interfacial tension. Typically, one can coat the core with a ligand for better interaction with the shell. By selecting suitable ligands, we have developed general encapsulation methods in three systems. A variety of nanoparticles and nanowires were encapsulated using either amphiphilic block copolymer (polystyrene-block-poly(acrylic acid)), conductive polymer (polyaniline, polypyrrole, or polythiophene), or silica as the shell material. Obvious uses of shells are to stabilize colloidal objects, retain their surface ligands, prevent particle aggregation, or preserve the assembled superstructures. These simple capabilities are essential in our synthesis of surface-enhanced Raman scattering nanoprobes, in assigning the solution state of nanostructures before drying, and in developing purification methods for nano-objects. When it is applied in situ during nanocrystal growth or nanoparticle assembly, the intermediates trapped by shell encapsulation can offer great insights into the mechanistic details. On the other hand, having a shell as a second component provides a window for exploring the core-shell synergistic effects. Hybrid core-shell nanocrystals have interesting effects, for example, in causing the untwisting of nanowires to give double helices. In addition, partial polymer shells can bias nanocrystal growth towards one direction or promote the random growth of Au dendritic structures; contracting polymer shells can compress the embedded nanofilaments (Au nanowires or carbon nanotubes), forcing them to coil into rings. Also, by exploiting the sphere-to-cylinder conversion of block copolymer micelles, the Au nanoparticles pre-embedded in the polymer micelles can be assembled into long chains. Lastly, shells are also very useful for mechanistic studies. We have demonstrated such applications in studying the controlled aggregation of nanoparticles, in probing the diffusion kinetics of model drug molecules from nanocarriers to nanoacceptors, and in measuring the ionic diffusion through polyaniline shells.

Impurity-related degradation in a prototype organic photovoltaic material: A first-principles study

The phenyl-C61-butyric acid methyl ester (PCBM) fullerene derivative is among the most widely used acceptor materials in organic photovoltaics (OPVs). Similar to the case of several other organic semiconductors and systems, experimental data show that the performance of OPV blends of PCBM with a polythiophene polymer degrades when the system is exposed to ambient molecules, such as O2 and H2O. Here we use first-principles calculations to identify physical mechanisms that can give rise to this type of degradation. We find that oxygen impurities can be incorporated in PCBM crystals and form several different types of configurations that range from intact molecules in crystalline voids to oxidized PCBM molecules. A number of O-related impurity structures generate states within the energy band gap of the PCBM crystal, creating thus shallow and deep carrier traps. Likewise, incorporation of H2O molecules gives rise to a shallow acceptor-like trap. The results are consistent with pertinent experimental observations of degradation paths for air-exposed PCBM samples and can aid in the optimization of PCBM-based OPV blends.

2-Thiopheneacetic Acid Directed Synthesis of Au Nanorosette as an SERS-Active Substrate

Rosette-like nanoscale Au materials were simply prepared through one-pot reduction of the AuCl₄⁻ precursor by 2-thiopheneacetic acid (2-TAA) without extra surface capping ligands at room temperature. 2-TAA underwent polymerization into polythiophene derivatives while the AuCl₄⁻ precursor was simultaneously reduced into various Au nanostructures. In situ generated polythiophene derivatives played a significant role of surface passivation in guiding the shape of Au nanostructures. The morphology of Au nanostructures was strongly dependent on the molar ratio of 2-TAA to AuCl₄⁻. At lower [2-TAA]/[AuCl₄⁻] ratios, uniform rosette-like Au microparticles consisting of 30-nm-thick Au nanoplates were observed. The Au nanoplates had either triangular prismatic or hexagonal geometry with many defects. Uniform Au nanorosettes could be easily deposited on the Si substrate by drop-casting and were subsequently used as highly active SERS substrates for the detection of methylene blue and crystal violet by Raman spectroscopy. Upon increasing the ratio of [2-TAA]/[AuCl₄⁻], Au nanoparticles or nanorods heavily surrounded with polythiophene polymers were obtained.

Challenging identifications of polymer coatings by radiofrequency pulsed glow discharge-time of flight mass spectrometry

Radiofrequency pulsed glow discharge (RF-PGD) coupled to time of flight mass spectrometry (TOFMS) has become a powerful tool for obtaining both elemental and molecular information directly from solid samples. Two GD Grimm-type based designs coupled to TOFMS are compared for the analysis of polymers. One of the chambers is an in-house design (“UNIOVI GD”), while the other (named “GD.1”) corresponds to the source included in the initial GD-TOFMS prototype. Operating conditions were similar for both GD designs (15 W of applied power with both chambers, 200 Pa of pressure for GD.1 and 150 Pa for the UNIOVI GD), with argon being the plasma gas used. Experimental results showed that the GD.1 design provides richer molecular information and also better detection limits for polyatomic ions (in the low μg g−1 range); this fact could be attributed to higher distance between the sample and the mass spectrometric interface in GD.1 design. Furthermore, this GD source contains a flow tube inside the anode favouring the formation of polyatomic ions and, thus, providing higher molecular information. Moreover, the use of an argon pre-chamber to minimize the entry of external air, which could interfere in the sought polymer identification, has been successfully evaluated as well. Finally, four conductive polymers (polyaniline, polyphenylene sulfide, polypyrrole and polythiophene) containing carbon, hydrogen and either sulphur or nitrogen have been characterized using RF-PGD-TOFMS (using the GD.1 chamber and the Ar pre-chamber). Results showed that some of the polyatomic ions can be eventually considered as fragments coming from the structures of the corresponding monomers constituting each polymer. Thus, the molecular information provided by RF-PGD-TOFMS under appropriate experimental conditions enables a fast and reliable identification of the studied polymers.

Preparation and Characterization of Thin Conductive Polymer Films on the base of PEDOT:PSS by Ink-Jet Printing

Owing to its high application potential, the printed functional layers and devices on flexible substrates attract attention of many scientists, in the last few years. Very promising area is represented by so called printed conductive polymers (polyaniline, polythiophene or polypyrroles, etc.). Currently, the most widespread conductive polymer is so called PEDOT:PSS [poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)]. A widely used technique for the deposition of this conductive polymer is spin-coating. Since the spin-coating technique is not capable of the fine structure pattering (e.g. electrode systems for organic devices), in some cases, different techniques are strongly required (e.g. ink-jet printing). This work shows the development of the testing structure system to assess and to characterize the fine patterns of PEDOT:PSS. The testing structures were deposited on various substrates; the transparent flexible polymer foils (polyethylenterephtalate and polyethylenenaphtalene) and also on the glass substrate. The influence of the change of printing parameters, substrate and its treatment and are discussed.

Photoluminescence characterization of polythiophene films incorporated with highly functional molecules such as metallophthalocyanine.

The photoluminescence (PL) of conducting polymer polythiophene (PT) films incorporated with metallophthalocyanines (PcMs) such as CuPc, MgPc, FePc, Li2Pc, and CoPc was studied by PL and time-correlated single photon counting (TCSPC) measurements. Polymer films were prepared by electrochemical polymerization and PcMs migrated into the polymer films by a diffusion method using acetonitrile or toluene as a solvent to dissolve the PcMs. The wavelength of PL emission peaks changed significantly depending on the solvent used in the doping process. Using acetonitrile, the observed PL emission peaks originated from the Q band, whereas they were assigned to the Soret band in the case of toluene. TCSPC measurements showed that PL emission took place through a ligand-ligand transition process when using acetonitrile because the average lifetimes were comparable and independent of the central metal ions for CoPc-, Li2Pc-, and MgPc-doped polymer films. Conversely, using toluene, it was found that ligand-ligand emission occurred for Li2Pc-, MgPc-, and FePc-doped films. To identify the cause of the drastic change in PL emission pattern, x-ray photoelectron spectroscopy measurements were obtained. A lower binding energy component appeared in the C 1s core-level spectra of acetonitrile-processed PcM-doped PT films, whereas this component shifted to higher energy and overlapped with the main peak for toluene-processed PcM-doped PT films. The lower binding energy component corresponded to photoelectrons due to the C atoms in the benzene rings of the ligand. Lower binding energy components also appeared in the N 1s core-level spectra of acetonitrile-processed PcM-doped PT films, and this component shifted to higher energy for toluene-processed PcM-doped PT films. These lower energy components were assigned to the core-level peaks due to the N atoms at the meso position bridging between pyrrole rings. This suggests that the electron charge at the N sites of the meso positions in toluene-processed films was smaller than in acetonitrile-processed ones. The changes in energy at benzene C sites and meso N sites suggest that the electronic states of the phthalocyanine in the toluene-processed films were porphyrin-like, so the Soret band became dominant in the PL emission spectrum.

Preparation of highly aligned arrays of conducting polymer nanowires using templated electropolymerization in supercritical fluids

The electrochemical synthesis of conducting polymers (polythiophene and polypyrrole) within cylindrical pores in membranes as a template was carried out in a supercritical fluid such as supercritical trifluoromethane (scCHF3). The use of the special properties of the fluid such as higher diffusivility and lower viscosity enabled the effective monomer transport into the nanoporous template and the nanoprecise filling with the polymers. The height of the polymer nanowires electropolymerized in scCHF3 was appreciably uniform compared with that deposited in a liquid medium like an acetonitrile solution and the height was found to be correlated exactly with the deposition time. The diffusivility of media used for the electrodeposition also affected on strength and structures of the cylindrical-shaped polymer materials obtained by dissolving the membranes in NaOH aqueous solution. The highly aligned polymer nanowire arrays prepared by the present method showed better electrochemical behaviors compared to nanowires obtained in the acetonitrile electrolytic solution.