Poly(3, 4-ethylenedioxythiophene): Conductive coatings,technical applications and properties

Poly(3, 4-ethylenedioxythiophene) (PEDT) is a new polymeric organic conductor which, when combined with polystyrene sulphonic acid, produces a system that can be processed as an aqueous solution and yields effective antistatic coatings for films. The antistatic effect is achieved with coating weights of just a few mg PEDT/m², resulting in films with a surface resistivity of 10⁶ ω/□.     

An intrinsic antistatic polyethylene glycol-based solid–solid phase change material for thermal energy storage and thermal management

Polyethylene glycol (PEG) is an important and popular phase change material (PCM), but is not a good antistatic material, which would cause the accumulation of static electricity and electrostatic discharge when used for the thermal energy storage and thermal management of electrical devices. Herein, we prepared a PEG-based solid–solid PCM (SSPCM) with good antistatic property by introducing an ionic liquid onto the macromolecular chains. This SSPCM is in solid state even at 90°C, avoiding the leakage issue of pure PEG. Its latent heat values in the melting and solidifying processes are 56.2 and 30.6 J g⁻¹, respectively. Additionally, this SSPCM has good thermal stability and thermal reliability for thermal storage and thermal management according to thermogravimetric and thermal cycling tests. The volume- and surface resistivity of the SSPCM at ambient temperature are 10^8.87 Ω m and 10^8.92 Ω, respectively, showing good antistatic performance.     

Enhanced toughness and strength of conductive cellulose-poly(butylene succinate) films filled with multiwalled carbon nanotubes

Cellulose (CE) composite films with high tensile strength, modulus, remarkable elongation as well as excellent electrical conductivity were successfully prepared by dispersing poly(butylene succinate) (PBS) and multiwalled carbon nanotubes (MWCNTs) in CE matrix via the help of ionic liquid 1-allyl-3-methylimidazolium chloride. Fourier transform infrared spectroscopy and differential scanning calorimetry results verified that a physical interaction junction existed between PBS and CE. Scanning electron micrograph (SEM) showed that the low content PBS was uniformly dispersed in CE matrix, leading to a tough and ductile fractured surface. The elongation at break of CE composite film with 1 wt% PBS was increased to 25.9 %, which showed an increase of 325 % compared to that of neat CE film (6.07 %). But high-content PBS acted as the structural defect in the CE matrix. MWCNTs were further added to improve the mechanical and conductive properties of the composite film. The tensile strength and Young’s modulus of MWCNT/CE-PBS composite film with 4 wt% MWCNTs were respectively increased by 33.6 and 140 % compared to CE-PBS film. The electrical conductivity of MWCNT/CE-PBS film was also improved by 8–9 orders of magnitude from 2.5 × 10^?14 to 1.3 × 10^?5 S/m.     

Conducting films of poly(aniline‐co‐1‐amino‐ 2‐naphthol‐4‐sulfonic acid) blended with LDPE for its application as antistatic encapsulation material

The paper presents the electrostatic charge dissipative (ESD) properties of the conducting copolymers of aniline (AN) and 1‐amino‐2‐naphthol‐4‐sulfonic acid (ANSA) blended with low‐density polyethylene (LDPE). The copolymers of aniline and ANSA were synthesized under different reaction conditions. Blending of copolymers with LDPE was carried out in twin screw extruder by melt blending method by loading 0.5 and 1.0 wt% of the conducting copolymer in LDPE matrix. The mechanical properties of the blended films depend on the incorporation of copolymer in the LDPE matrix. The morphology of copolymer–LDPE blend was studied by scanning electron microscopy. The conductivity of the blown film of poly(AN‐co‐ANSA)/LDPE blend was found to be in the range of 10^?6–10^?11 S/cm, showing its potential use as antistatic bag for the encapsulation of electronic equipments. The static decay time of the film was found to be of the order of 0.1–1.9 sec on recording the decay time from 5000 to 500 V. Static charge measurements carried out on the films show that no charge is present on the surface. The level of interaction between the copolymers and the matrix polymer was determined by the FTIR spectra, blend morphology, electrical conductivity, and thermal analysis. The effect of the morphology on electrical and antistatic behavior of copolymers has also been investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

新型软质抗静电聚氯乙烯材料的研究

合成了一种长链季铵盐类化合物, 将其用作抗静电剂添加到软质聚氯乙烯(PVC)材料中, 测试了材料的表面电阻、力学性能, 并采用扫描电子显微镜测试研究了其结构. 结果表明: 随合成长链季铵盐的添加量增大, PVC材料的表面电阻率降低, 较小的添加量(4.5%)即可使材料的表面电阻率降低至3.0×10⁸ Ω以下, 达到了煤矿行业对高分子材料抗静电性能的要求. 在上述抗静电PVC材料中添加一定量的聚氧化乙烯(PEO), 可以降低抗静电材料对环境湿度的依赖性, 并提高PVC材料的力学性能和抗静电性能.     

The tribological performance of fullerene‐like hydrogenated carbon films under ionic liquid lubrication

Fullerene‐like hydrogenated carbon films were deposited on Si substrate by plasma‐enhanced chemical vapor deposition. The microstructures of films were characterized by high‐resolution transmission electron microscopy and Raman spectrum. The tribological performance of films was tested by reciprocating ball‐on‐disc tester under 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid. The surface morphology and chemical composition of wear tracks and wear rates were investigated by optical microscope, X‐ray photoelectron spectroscopy, and 3D surface profiler. The results indicated that the film with a typical fullerene‐like structure embedded into the amorphous sp² and sp³ carbon networks could be prepared successfully, and the film shows a higher hardness (26.7 GPa) and elastic recovery (89.9%) compared with the amorphous carbon film. Furthermore, the film shows a lower friction coefficient at low contact load and friction frequency, and excellent wear‐resistance performance at high load and frequency under ionic liquid lubrication. Meanwhile, the wear life of fullerene‐like hydrogenated carbon films could be improved significantly using ionic liquid as a lubrication material. Copyright © 2015 John Wiley & Sons, Ltd.     

XPS analysis of the poly(ethylene terephthalate) film grafted with acrylamide

Graft polymerization of acrylamide (AAm) was performed onto the surface of a poly(ethylene terephthalate) (PET) film with the simultaneous UV irradiation method but using no photosensitizer and without degassing. To examine whether polyacrylamide (PAAm) was introduced into the bulk place of PET film by the surface graft polymerization, an x-ray photoelectron spectroscopic (XPS) study was performed on the PAAm-grafted PET films. The distribution of grafted PAAm chains on and in the PET films was estimated from the PAAm/PET ratio calculated from the XPS spectra of PET films with different amounts of grafted PAAm. The results clearly demonstrate that graft polymerization has actually occurred not merely on the outermost surface but also within the thin surface region of the PET film. In addition, the XPS analysis revealed that the PET component was always present in the grafted surface region by a mole fraction of 0.1 to 0.05 even when the amount of PAAm grafted was larger than 10 μg/cm².     

CHANGES OF STRUCTURE AND PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE) CAUSED BY IN-SITU POLYMERIZATION OF PYRROLE

Conductive polymer composites based on crystalline polymer matrix have been prepared by using an in-situ polymerization process of pyrrole in amorphous poly (ethylene terephthalate) (PET) film. The DSC and WAXD measurement and SEM observation show that liquid-induced crystallization of PET matrix has occurred during the preparation of composite films. Depending upon the equilibrium degree of swelling and crystallinity, the limited depth of penetration of pyrrole molecules results in a skin-core structure of the composite film. The skin layer containing charge transfer intercalated polypyrrole has a surface resistance of 3.5×10~4 Ω. Rigid and heat-resistant polypyrrole molecules formed in PET film increase the tensile modulus and, especially, the rigidity of PET at elevated temperatures. However, they decrease the tensile strength and elongation at break, and impair the thermal ductility of PET.     

Electroless Copper Plating on Liquid Crystal Polymer Films Using Dimethylamine Borane as Reducing Agent

Dimethylamine borane (DMAB) was used in electroless copper plating on liquid crystal polymer (LCP) films. An orthogonal test was applied to optimize the plating condition. With Cu film resistivity as the evaluation index, the optimum plating condition is: 10 g/L of CuSO₄ ? 5H₂O, 14 g/L of EDTA‐2Na, 6 g/L of DMAB, 9.5 of pH value and 50 °C. As pH value increases, the Cu film resistivity decreases and the depo‐ sition rate increases. As temperature increases, the Cu film resistivity decreases first and then increases with a minimum at 50 °C while the deposition rate increases first and then decreases with a maximum at 50 °C. The decreased Cu film resistivity can be attributed to the occurrence of CuO. The adhesive strength of copper layer to LCP film is constant at pH values lower than 8.5 and decreases slightly with the increase in pH value. As temperature increases, the adhesive strength decreases slightly. The decreased adhesive strength with both pH and temperature may be a result of an increased corrosion attack from the bath to the surface of LCP films. Low Cu film resistivity and high deposition rate as well as high adhesive strength can be obtained using DMAB reducing agent.     

Electrochemical synthesis and investigation of poly(1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene) and its application in an electrochromic device

1,4-Bis(2-(3,4-ethylenedioxy)thienyl)benzene, prepared by Stille cross-coupling reaction was successfully electrochemically polymerized to give polymer 1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene (PEBE). Characterizations of the resulting polymer PEBE were performed by cyclic voltammetry (CV), UV–vis, Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the spectroelectrochemical and electrochromic properties of the polymer film were investigated. The resulting polymer film has distinct electrochromic properties and shows three different colors (deep red, gray, and light blue) under various potentials. At the dedoped state of the polymer, the π–π* transition absorption peak is located at 510?nm and the optical band gap (E _g) was calculated as 1.92?eV. The PEBE film shows a maximum optical contrast (ΔT%) of 31.0?% at 500?nm with a response time of 0.85?s. The coloration efficiency of PEBE film was calculated to be 182.2?cm²C^?1. An electrochromic device (ECD) based on PEBE and poly(3,4-ethylenedioxythiophene) was also constructed and characterized. The response time was measured as 0.4?s, and the coloration efficiency of the device was calculated to be 225.4?cm²C^?1. Furthermore, this ECD exhibited satisfactory optical memories and redox stability.     

Permanently antistatic and high transparent PMMA terpolymer: Compatilizer,antistatic agent,and the antistatic mechanism

Permanently antistatic and high transparent PMMA terpolymer, P(MMA‐co‐HPA‐co‐SPMA), were reported in this paper, providing a new method to significantly improve the antistatic properties of PMMA without sacrificing transparency. 2‐Hydroxypropyl acrylate (HPA) was chosen as a kind of compatilizer because of the good compatibility with both methyl methacrylate (MMA) and sulfopropyl methacrylate potassium salt (SPMA), a potential antistatic agent with a strong hydrophilic group. The mechanical and optical properties of P(MMA‐co‐HPA‐co‐SPMA) terpolymer barely show any visibly differences compared to PMMA homopolymer, confirmed through Fourier transform infrared, dynamic mechanical analysis, and a haze meter. Furthermore, antistatic property analysis indicates that only a small amount of SPMA can significantly improve the antistatic properties of the obtained PMMA terpolymers. The surface resistivity of the P(MMA‐co‐HPA‐co‐SPMA) sheets could be reduced to 10⁹ Ω sq⁻¹ order of magnitude, while the SPMA content reached 0.72 wt%. The hydrophilic groups, the hydroxyl and acrylate sulfonate, on the surface contributed to attract the water molecules, which rendered it a reasonably good antistatic property. These selected terpolymers will provide more opportunities to develop high‐performance and antistatic products made from PMMA materials.     

Study of the optimal condition for electroplating of Bi2S3 thin films and their photoelectrochemical characteristics

Bismuth sulfide (Bi₂S₃) thin films were electrodeposited from non-aqueous dimethyl sulfoxide medium containing Bi(NO₃)₃ and thiourea as the precursor salts, triethanol amine as the complexing agent, and TritonX-100 as the surface active agent. The prepared films were subjected to rigorous experimentation in order to validate their potential candidature for solar cells. The films exhibited band gap energy of ∼1.3 eV and resistivity of the order of 2 × 10⁶ Ω cm at room temperature as was obtained from UV–Vis spectroscopy and four-probe measurements, respectively. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy dispersive analysis of X-ray were employed to reveal the morphology, structure, and chemical composition of the film matrix. The Bi₂S₃ films were found to be non-decomposable up to the temperature of 1,000 °C with the help of thermogravimetry–differential thermal analysis. The Nyquist and Mott–Schottky plots derived from electrochemical impedance spectroscopy measurements provided important information regarding electrical and semiconducting properties of the films. The n-type film with a donor density of the order of ∼10²³ m⁻³ displayed reasonable photoactivity under illumination and is recommended as a promising candidate for potential photoelectrochemical applications.     

The Effect of Ionic Liquid Covalent Bonding to Sol‐Gel Processed Film on Ion Accumulation and Transfer

Accumulation of electroactive anions into a silicate film with covalently bonded room temperature ionic liquid film deposited on an indium tin oxide electrode was studied and compared with an electrode modified with an unconfined room temperature ionic liquid. A thin film containing imidazolium cationic groups was obtained by sol‐gel processing of the ionic liquid precursor 1‐methyl‐3‐(3‐trimethoxysilylpropyl)imidazolium bis(trifluoromethylsulfonyl)imide together with tetramethylorthosilicate on the electrode surface. Profilometry shows that the obtained film is not smooth and its approximate thickness is above 1 μm. It is to some extent permeable for a neutral redox probe – 1,1′‐ferrocene dimethanol. However, it acts as a sponge for electroactive ions like Fe(CN)₆^3?, Fe(CN)₆^4? and IrCl₆^3?. This effect can be traced by cyclic voltammetry down to a concentration equal to 10^?7 mol dm^?3. Some accumulation of the redox active ions also occurs at the electrode modified with the ionic liquid precursor, but the voltammetric signal is significantly smaller compare with the bare electrode. The electrochemical oxidation of the redox liquid t‐butyloferrocene deposited on silicate confined ionic liquid film is followed by the expulsion of the electrogenerated cation into an aqueous solution. On the other hand, the voltammetry obtained with the electrode modified with t‐butyloferrocene solution in the ionic liquid precursor exhibits anion sensitive voltammetry. This is explained by anion insertion into the unconfined ionic liquid deposit following t‐butylferricinium cation formation.     

Antistatic ability of 1-n-tetradecyl-3-methylimidazolium bromide and its effects on the structure and properties of polypropylene

In this study, 1-n-tetradecyl-3-methylimidazolium bromide ([C₁₄mim]Br), one kind of imidazolium ionic liquid (imi-IL), was incorporated into polypropylene (PP) via melt blending. The measurement of surface resistance (R_s) and volume resistance (R_v) of neat PP and PP/[C₁₄mim]Br blends indicated that [C₁₄mim]Br had excellent antistatic properties. The PP/[C₁₄mim]Br blend had the best antistatic ability, when the weight ratio of [C₁₄mim]Br to PP reached 3/100. The surface resistance of PP/[C₁₄mim]Br decreased from the 7.67 × 10¹³ to 1.40 × 10⁷ Ω whereas the volume resistance of PP decreased from 2.67 × 10¹⁴ to 2.60 × 10⁷ Ω. Semicrystalline morphology and crystal structure were investigated by polarized optical microscopy (POM) and X-ray diffraction (XRD). The spherulites of PP became smaller with the addition of [C₁₄mim]Br, implying that [C₁₄mim]Br had a nucleating effect in the PP matrix. The XRD study indicates the crystallization process of PP was affected by [C₁₄mim]Br, and the crystallinity of PP was thus decreased. Scanning electron microscopy (SEM) studies reveal that [C₁₄mim]Br had good dispersion in PP; thermogravimetric analysis (TGA) shows the addition of [C₁₄mim]Br remarkably increased the thermal stability of PP even though it is a small molecule.     

Electrochemical polymerization of imidazolum‐ionic liquids bearing a pyrrole moiety

A series of imidazolium‐based ionic liquid monomers bearing a terminal pyrrole moiety were synthesized and electrochemically polymerized. It is found that the polymerizability of the synthesized ionic liquids is strongly dependent on the type of the counteranions. Although bromide monomer is not polymerizable, well‐defined polymeric films can be formed on various substrates in the cases of flour‐containing anions (BF₄^?, PF₆^?). The performed characterizations show that all resulting polypyrrole films are electroactive, and the imidazolium‐based ionic liquid moieties are correctly incorporated in polymer films during the electropolymerization process. This work not only provides a facile new method to immobilize ionic liquids on solid surface. Interestingly, without use of any template unique “knit” morphology and nanostructure, even hierarchical structures could also be produced by the electropolymerization of these new functionalized pyrrole monomers. We found that the properties of the pendant ionic liquid units on the surface of the formed polymer films preserved, and by simple anion exchange their surface energy and tension could be easily tuned without loss of the electrical, optical properties, and morphology of the polypyrrole films. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4151–4161, 2008     

New polymer electrolyte membrane for medium-temperature fuel cell applications based on cross-linked polyimide Matrimid and hydrophobic protic ionic liquid

New hydrophobic protic ionic liquid, 2-butylaminoimidazolinium bis(trifluoromethylsulfonyl)imide (BAIM-TFSI), has been synthesized. The ionic liquid showed good thermal stability to at least 350 °C. The conductivity of BAIM-TFSI determined by electrochemical impedance method was found to be 5.6 × 10^?2 S/cm at 140 °C. Homogeneous composite films based on commercial polyimide (PI) Matrimid and BAIM-TFSI containing 30–60 wt% of ionic liquid were prepared by casting from methylene chloride solutions. Thermogravimetric analysis data indicated an excellent thermal stability of PI/BAIM-TFSI composites and thermal degradation points in the temperature range 377 °C–397 °C. The addition of ionic liquid up to 50 wt% in PI films does not lead to any significant deterioration of the tensile strength of the polymer. The dynamic mechanical analysis results indicated both an increase of storage modulus E′ of PI/BAIM-TFSI composites at room temperature and a significant E′ decrease with temperature compared with the neat polymer. The cross-linking of the PI with polyetheramine Jeffamine D-400 allowed to prepare PI/Jeffamine/BAIM-TFSI (50%) membrane with E′ value of 300 MPa at 130 °C. The ionic conductivity of this cross-linked composite membrane reached the level of 10^?2 S/cm at 130 °C, suggesting, therefore, its potential use in medium-temperature fuel cells operating in water-free conditions.     

Improving electrochemical performance of poly(vinyl butyral)-based electrolyte by reinforcement with network of ceramic nanofillers

This study has concerned the development of polymer composite electrolytes based on poly(vinyl butyral) (PVB) reinforced with calcinated Li/titania (CLT) for use as an electrolyte in electrochemical devices. The primary aim of this work was to verify our concept of applying CLT-based fillers in a form of nano-backbone to enhance the performance of a solid electrolyte system. To introduce the network of CLT into the PVB matrix, gelatin was used as a sacrificial polymer matrix for the implementation of in situ sol–gel reactions. The gelatin/Li/titania nanofiber films with various lithium perchlorate (LiClO₄) and titanium isopropoxide proportions were initially fabricated via electrospinning, and ionic conductivities of electrospun nanofibers were then examined at 25 °C. In this regard, the highest ionic conductivity of 2.55 × 10⁻⁶ S/cm was achieved when 10 wt% and 7.5 wt% loadings of LiClO₄ and titania precursor were used, respectively. The nanofiber film was then calcined at 400 °C to remove gelatin, and the obtained CLT film was then re-dispersed in solvated PVB-lithium bis(trifluoromethanesulfonyl)imide (PVB-LiTFSI) solution before casting to obtain reinforced composite solid electrolyte film. The reinforced composite PVB polymer electrolyte film shows high ionic conductivity of 2.22 × 10⁻⁴ S/cm with a wider electrochemical stability window in comparison to the one without nanofillers.

     

Synthesis and electro‐optical characterization of new conducting PEDOT/Au‐nanorods nanocomposites

This paper describes a new strategy to obtain PEDOT/Au‐nanorods nanocomposites with different PEDOT: Au ratio. A polymeric ionic liquid (PIL) was used as stabilizer during the chemical synthesis of PEDOT dispersions. PEDOT/Au‐nanorods dispersions in organic media were obtained. Electrochemical characterization of PEDOT/Au‐nanorods nanocomposites revealed that the addition of Au nanorods modified the electroactivity of the conducting films by reducing the oxidation potential from +0.33 to +0.23 V (versus Ag/AgCl). Optical contrast (ΔT%) of the films decreased from 17% for neat PEDOT films to 8% for PEDOT/Au‐nanorods nanocomposites films (3:1 (v/v)) while switching times (from 1 to 4 sec) were similar to neat PEDOT. Conductivity of the films increased from 0.027 S/cm for neat PEDOT to 0.691 S/cm for PEDOT/Au‐nanorods nanocomposites. Nanoscale morphology and contact potential of PEDOT/Au‐nanorods nanocomposites were investigated in detail by Scanning Force Microscopy. Electrical measurements show a clear contact potential difference between the ITO substrate and the PEDOT/Au‐nanorods film. On the film, no contact potential inhomogeneity is observed indicating that the Au‐nanorods are uniformly dispersed in the film. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of substrate temperature on properties of ITO-ZnO composition spread films fabricated by combinatorial RF magnetron sputtering

We have fabricated ITO-ZnO composition spread films to investigate the effects of substrate temperature on their electrical and optical properties by using combinatorial RF magnetron sputtering. It turned out by X-ray measurement that the film with zinc contents above 16.0 at% [Zn/(In+Zn+Sn)] showed amorphous phase regardless of substrate temperature. The amorphous ITO-ZnO film had lower resistivity than polycrystalline films. When the films were deposited at 250 °C, the minimum resistivity of 3.0×10⁻⁴ Ω cm was obtained with the zinc contents of 16.0 at%. The indium content could be reduced as high as ~30 at% compared to that of ITO for the films having similar resistivity (~10⁻⁴ Ω cm). However, a drastic increase of resistivity was observed for the ITO-ZnO films deposited at 350 °C, having zinc contents below 15.2 at%.     

Effect of EMIMBF4 ionic liquid addition on the structure and ionic conductivity of LiBF4-complexed PVdF-HFP polymer electrolyte films

New polymer electrolyte films of lithium tetrafluoroborate (LiBF₄)-complexed poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) embedded with different quantities of 1-ethyl-3methylimidazolium tetrafluoroborate (EMIMBF₄) ionic liquid were prepared by solution casting. The prepared films were characterized using various techniques: X-ray diffraction, scanning electron microscopy, impedance spectroscopy and electrochemical measurements. The pure PVdF-HFP possessed a semi-crystalline structure and its amorphicity increased with the addition of LiBF₄ salt and EMIMBF₄ ionic liquid. The size and interconnection of pores in the films were enhanced by EMIMBF₄. Impedance measurements indicated that the room-temperature ionic conductivity of the films increased with increasing EMIMBF₄ concentration until 15 wt.%, being up to 0.202 × 10⁻⁴ S cm⁻¹, and then decreased with further increasing EMIMBF₄ concentration. In addition, the temperature-dependent ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the 15 wt.% EMIMBF₄-incorporated gel polymer electrolyte film exhibited a low activation energy for ionic conduction, being about 0.28 eV. Finally, the electrochemical stability window of the 85PVdF-HFP:15LiBF₄+15 EMIMBF₄ gel polymer electrolyte films was evaluated as approximately 4.4 V, which is a promising value for ion battery applications.