Electrochemistry and Ion Sensing Properties of Conducting Hydrogel Layers Based on Polypyrrole and Alkoxysulfonated Poly(3,4‐ethylenedioxythiophene) (PEDOT‐S)

Acidic aqueous solutions containing pyrrole and alkoxysulfonated PEDOT derivative (PEDOT‐S) were found to undergo polymerization in the absence of an external oxidizing agent. The product was a nearly black‐colored conducting hydrogel that after separation could be dispersed in water or acetone. The suspensions could be used to deposit cast films on a polycrystalline gold electrode. The polymer modified electrode showed a nearly Nernstian potentiometric response to Ag⁺ cations in the concentration range of 10^?5–10^?1 M with the slope of 54 mV/decade. The response was specific to Ag⁺ compared to a series of alkali and transition‐metal cations (pK_Ag/M>3.7).     

Single‐Piece Solid‐Contact Pb2+‐Selective Electrodes Based on Thiophene Oligomer

A single‐piece solid‐contact Pb²⁺‐selective electrode was prepared by adding a thiophene oligomer into the ion‐selective cocktail directly. The one‐step fabrication yielded an electrode with Nernstian response spanning a wide concentration range of 10^?3–10^?8 mol L^?1, and detection limit as low as 5.6×10^?9 mol L^?1. The electrode had a quick response time of approximately 10–15 s and showed excellent selectivity over the most common univalent and divalent cations. The practical application of the proposed electrode has been tested by determining Pb²⁺ in real water samples.     

Potentiometric Ag+ Sensors Based on Conducting Polymers: A Comparison between Poly(3,4‐ethylenedioxythiophene) and Polypyrrole Doped with Sulfonated Calixarenes

Potentiometric Ag⁺ sensors were prepared by galvanostatic electropolymerization of 3,4‐ethylenedioxythiophene (EDOT) and pyrrole (Py) on glassy carbon electrodes by using sulfonated calixarenes as doping ions. Poly(3,4‐ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) doped with p‐sulfonic calix[4]arene (C4S), p‐sulfonic calix[6]arene (C6S) and p‐sulfonic calix[8]arene (C8S) were compared. PEDOT and PPy doped with poly(styrene sulfonate) (PSS) were also included for comparison. The analytical performance of the conducting polymer‐based Ag⁺ sensors was studied by potentiometric measurements. All conducting polymer and dopant combinations showed sensitivity and selectivity to Ag⁺ compared to several alkali, alkaline‐earth, and transition‐metal cations. The type of the conducting polymer used for the fabrication of the electrodes was found to have a more significant effect on the selectivity of the electrodes to Ag⁺ than the ring size of the sulfonated calixarenes used as dopants. Selected conducting polymer‐based sensors were studied by cyclic voltammetry (CV) and energy dispersive analysis of X‐rays (EDAX) measurements. Results from the EDAX measurements show that both PEDOT‐ and PPy‐based membranes accumulate silver.     

Tailoring Solution Cast Poly(3,4‐dioctyloxythiophene) Transducers for Potentiometric All‐Solid‐State Ion‐Selective Electrodes

A novel concept of tailoring potentiometric responses of all‐solid‐state ion‐selective electrodes was introduced. The effect of composition and resulting properties of the conjugated polymer transducer, placed between the electrode support and ion‐selective membrane, on analytical characteristic of obtained sensors was studied.     

Development of Pr(III) Selective Electrode Using 1,6,7,12‐Tetramine‐2,5,8,11‐tetraoxo‐1(12),6(7)‐di(biphenyl)‐dodecane (TATODBDD) as a Neutral Carrier

A polyvinyl chloride (PVC) membrane based Pr(III) selective electrode was constructed using 1,6,7,12‐tetramine‐2,5,8,11‐tetraoxo‐1(12),6(7)‐di(biphenyl)dodecane (TATODBDD) as a neutral carrier. The sensor exhibits a Nernstian response for Pr(III) ions, a wide concentration range of 3.9×10^?7?1.0×10^?1 mol/L with a detection limit of 5.0×10^?8 mol/L and slope of 19.5 mV/decade. The developed sensor revealed relatively good selectivity and high sensitivity for Pr(III) ions over the other lanthanide ions. The potentiometric response of the sensor is independent in the pH range 2.9–9.5. The advantages of sensor are low resistance, very fast response time (<10 s) with good selectivity. This sensor can be used up to 6 weeks without any divergences in potential response.     

Response Behavior of Poly(vinyl chloride)‐ and Polyurethane‐Based Ca2+‐Selective Membrane Electrodes with Polypyrrole‐ and Poly(3‐octylthiophene)‐Mediated Internal Solid Contact

The potentiometric response behavior of Ca²⁺‐selective poly(vinyl chloride) (PVC) and polyurethane (PU) membranes with different inner contacts has been compared. Evidence for the formation of a water film between membrane and internal contact and, hence, a less than optimal lower detection limit have been found for membranes directly in contact with bare Au or with polypyrrole generated by electropolymerization in the presence of KCl. A significantly better behavior is shown by membranes with polypyrrole prepared in the presence of potassium hexacyanoferrate. Best performances have been obtained with solvent‐cast poly(3‐octylthiophene) as the internal contacting layer. As compared with the PVC membranes, those with PU had a significantly worse performance throughout.     

Construction of a Highly Selective and Sensitive La(III) Sensor Based on N‐(2‐Pyridyl)‐N′‐(4‐methoxyphenyl)‐thiourea for Nano Level Monitoring of La(III) Ions

N‐(2‐Pyridyl)‐N′‐(4‐methoxyphenyl)‐thiourea (PMPT) was found to be a suitable neutral ion carrier for the construction of a highly selective and sensitive La(III) membrane sensor. Poly(vinyl chloride) (PVC) based membranes of PMPT with potassium tetrakis (p‐chlorophenyl) borate (KTpClPB) as an anionic excluder and oleic acid (OA), dibutyl phthalate (DBP), benzyl acetate (BA) and o‐nitrophenyloctyl ether (NPOE) as plasticizing solvent mediators were constructed and investigated as La(III) membrane sensors. A membrane composed of PMPT‐PVC‐KTpClPB‐BA with the ratio 8.0 : 35.0 : 3.0 : 54.0 works well over a very wide concentration range (4.0×10^?8 to 1.0×10^?1 M) with a Nernstian slope of 19.6±0.2 mV per decade of activity between pH values of 4.0 and 9.0. The detection limit of the sensor was calculated to be 2.0×10^?8 M (ca. 3.0 ppb). The sensor displays very good discrimination toward La(III) ions with regard to most common metal ions and lanthanide ions. The proposed sensor shows a short response time for whole concentration range (ca. 12 s). For evaluation of the analytical applicability of the La(III) sensor, it was successfully used as an indicator electrode for the titration of La(III) ions with EDTA. It was also applied to the determination of fluoride content of two mouth wash preparation samples and monitoring of La(III) ions in some binary and ternary mixtures.     

Electrochemical Determination of Pyrogallol at Conducting Poly(3,4‐ethylenedioxythiophene) Film‐Modified Screen‐Printed Carbon Electrodes

The electrochemical oxidation of pyrogallol at electrogenerated poly(3,4‐ethylenedioxythiophene) (PEDOT) film‐modified screen‐printed carbon electrodes (SPCE) was investigated. The voltammetric peak for the oxidation of pyrogallol in a pH 7 buffer solution at the modified electrode occurred at 0.13 V, much lower than the bare SPCE and preanodized SPCE. The experimental parameters, including electropolymerization conditions, solution pH values and applied potentials were optimized to improve the voltammetric responses. A linear calibration plot, based on flow‐injection amperometry, was obtained for 1–1000 µM pyrogallol, and a slope of 0.030 µA/µM was obtained. The detection limit (S/N=3) was 0.63 µM.     

Electrochemical Oxidation and Sensitive Determination of Acetaminophen in Pharmaceuticals at Poly(3,4‐ethylenedioxythiophene)‐Modified Screen‐Printed Electrodes

The current study reports electrocatalytic oxidation of acetaminophen at screen‐printed electrode (SPE) modified with electrogenerated poly(3,4‐ethylenedioxythiophene) (PEDOT) film. Cyclic voltammetric studies show that the SPE/PEDOT electrode lowers overpotentials and improves electrochemical behavior of acetaminophen (ACAP) in aqueous buffer solutions, compared to the bare SPE. Excellent analytical features are achieved, including high sensitivity, low detection limit and satisfactory dynamic range, by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and flow‐injection amperometry (FIA) under optimized conditions. The proposed methods obtain satisfactory results in detection of acetaminophen in two commercial tablets.     

Fabrication of Poly(L‐lactide)‐block‐Poly(ethylene glycol)‐block‐Poly(L‐lactide) Triblock Copolymer Thin Films with Nanochannels: An AFM Study

This paper aims to report the fabrication of biodegradable thin films with micro‐domains of cylindrical nanochannels through the solvent‐induced microphase separation of poly(L ‐lactide)‐block‐poly(ethylene glycol)‐block‐poly(L ‐lactide) (PLA‐b‐PEG‐b‐PLA) triblock copolymers with different block ratios. In our experimental scope, an increase in each of the block lengths of the PLA and PEG blocks led to both a variation in the average number density (146 to 32 per 100 µm²) and the size of the micro‐domains (140 to 427 nm). Analyses by atomic force microscopy (AFM) and fluorescence microscopy indicated that the hydrophilic PEG nanochannels were dispersed in the PLA matrix of the PLA‐b‐PEG‐b‐PLA films. We demonstrated that the micro‐domain morphology could be controlled not only by the block length of PEG, but also by the solvent evaporation conditions.

     

Comparison of Multi‐walled Carbon Nanotubes and Poly(3‐octylthiophene) as Ion‐to‐Electron Transducers in All‐Solid‐State Potassium Ion‐Selective Electrodes

Multi‐walled carbon nanotubes (MWCNTs) were compared with poly(3‐octylthiophene) (POT) as ion‐to‐electron transducer in all‐solid‐state potassium ion‐selective electrodes with valinomycin‐based ion‐selective membranes. MWCNTs and POT were mixed with the other components of the potassium ion‐selective membrane cocktail (valinomycin, KTpClPB, o‐NPOE, PVC, THF) which was then applied on a glassy carbon (GC) substrate to prepare single‐piece ion‐selective electrodes (SPISEs). Results from potentiometric and impedance measurements showed that the MWCNT‐based electrodes have a more reproducuible standard potential and a lower overall impedance than the electrodes based on POT. Both types of electrodes showed similar sensitivity to potassium ions and no redox sensitivity.     

Membrane Composition Effects on the Analytical Behavior of Solid Contact Potentiometric Pb2+ Selective Electrodes Based on Diazadibenzo‐18‐crown‐6 Ionophores

The effect of component contents and membrane thickness on the detection limit (DL), slope (m), linear range (LR) and response time (RT) of Pb²⁺ solid contact potentiometric ion selective electrodes (SCISE) based on 4,10‐diaza‐2,3,11,12‐dibenzo‐18‐crown‐6 (1), 4,10‐diaza‐2,3,11,12‐di(4‐tert‐butylbenzo)‐18‐crown‐6 (2) and 4,10‐diaza‐2,3,11,12‐dibenzo‐18‐crown‐6‐N,N′‐di(carboxymethyl) (3) as ionophores was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The use of an intermediate layer of poly(3‐octyl)thiophene between the gold substrate and the selective membrane was explored. SCISE prepared showing the best responses had typical DL, m, LR and RT values of 10^?6 M, 29 mV/dec, 10^?5 to 10^?3 M and 2 minutes.     

TH‐11, a Streptomyces sp. Strain that Degrades Poly(3‐Hydroxybutyrate) and Poly(Ethylene Succinate)

TH‐11, a bacterial strain with strong depolymerase activity that breaks down aliphatic esters such as poly(3‐hydroxybutyrate) (PHB) and poly(ethylene succinate) (PES) was isolated from a soil sample collected from the sediment of Tou‐Chain River, Taiwan, R.O.C. It was phenotypically and genetically characterized to be a Streptomyces strain. The degradation of PHB and PES were tested both using emulsified polymers in solid agar and thin polymer films in liquid culture media. The degradations were measured by clear‐zone formation on solid agar plates, or direct weight measurements and electromicroscope inspection of the incubated polymer films in the liquid culture. The depolymerase activities can be detected in the cell‐free preparation of the culture medium, and can be enhanced by gelatin.     

A Convenient Oxidation of 5‐Substituted Pyrazol‐3(2H)‐Ones Into Methyl 2‐Alkynoates Using Poly[4‐(Diacetoxyiodo)Styrene]

An operationally simple oxidation of 5‐substituted pyrazol‐3(2H)‐ones to the corresponding methyl‐2‐alkynoates in good yields with a mediated poly[4‐(diacetoxyiodo)styrene] system in methanol and acetonitrile at room temperature was carried out. The polymeric reagent can be regenerated and reused as an environmentally benign reagent.     

Electrochemiluminescence Characterization of Poly(luminol‐benzidine) Composite Films and Their Analytical Application

A composite film of poly(luminol‐benzidine) was prepared on the graphite electrode surface by electropolymerizing luminol and benzidine in acidic medium. It was found that the poly(luminol‐benzidine) composite film presented better electrochemiluminescence (ECL) analytical performances for H₂O₂ than that of the polyluminol film. Based on these findings, a more sensitive ECL sensor for H₂O₂ was developed. At the same time, our investigating results on this composite film revealed that, as a real ECL luminophor in this composite film, the polymeric 3‐aminophthalate presented higher fluorescence quantum yield than that in the pure polyluminol film, which suggested that the excellent ECL performances of the composite film may originate from the enhancement of the ECL luminophor quantum yield. Based on these results, a new method to improve the ECL analytical performances of the polymeric luminol was also proposed.     

Highly Conductive PEDOT:PSS Films with 1,3‐Dimethyl‐2‐Imidazolidinone as Transparent Electrodes for Organic Light‐Emitting Diodes

Highly conductive poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films as transparent electrodes for organic light‐emitting diodes (OLEDs) are doped with a new solvent 1,3‐dimethyl‐2‐imidazolidinone (DMI) and are optimized using solvent post‐treatment. The DMI doped PEDOT:PSS films show significantly enhanced conductivities up to 812.1 S cm⁻¹. The sheet resistance of the PEDOT:PSS films doped with DMI is further reduced by various solvent post‐treatment. The effect of solvent post‐treatment on DMI doped PEDOT:PSS films is investigated and is shown to reduce insulating PSS in the conductive films. The solvent posttreated PEDOT:PSS films are successfully employed as transparent electrodes in white OLEDs. It is shown that the efficiency of OLEDs with the optimized DMI doped PEDOT:PSS films is higher than that of reference OLEDs doped with a conventional solvent (ethylene glycol). The results present that the optimized PEDOT:PSS films with the new solvent of DMI can be a promising transparent electrode for low‐cost, efficient ITO‐free white OLEDs.

     

Poly(3,4‐ethylenedioxythiophene) Derived from Poly(ionic liquid) for the Use as Hole‐Injecting Material in Organic Light‐Emitting Diodes

We report that poly(3,4‐ethylenedioxythiophene) derived from poly(ionic liquid) (PEDOT:PIL) constitutes a unique polymeric hole‐injecting material capable of improving device lifetime in organic light‐emitting diodes (OLEDs). Imidazolium‐based poly(ionic liquid)s were engineered to impart non‐acidic and non‐aqueous properties to PEDOT without compromising any other properties of PEDOT. A fluorescent OLED was fabricated using PEDOT:PIL as a hole‐injection layer and subjected to a performance evaluation test. In comparison with a control device using a conventional PEDOT‐based material, the device with PEDOT:PIL was found to achieve a significant improvement in terms of device lifetime. This improvement was attributed to a lower indium content in the PEDOT:PIL layer, which can be also interpreted as the effective protection characteristics of PEDOT:PIL for indium extraction from the electrodes.

     

Highly Selective and Sensitive Perchlorate Sensors Based on Some Recently Synthesized Ni(II)‐Hexaazacyclotetradecane Complexes

Three nickel(II)‐hexaazacyclotetradecane complexes were studied to characterize their abilities as perchlorate ion carrier in PVC membrane electrodes. The electrodes based on these complexes exhibit Nernstian responses for ClO over very wide concentration ranges (1.0×10^?1 ?5.0×10^?7 M) with detection limits of 2.0×10^?7 ?5.0×10^?7 M (20–50 ng/mL). The sensors show very good selectivity for ClO ion in comparison with the most common organic and inorganic anions. The responses of the proposed electrodes are independent of pH in the range of 3.5–11.0. The perchlorate selective membranes show fast response time (<10 s) and can be used for 4–12 weeks without any major deviation. The sensors were successfully used to determine the perchlorate ion in water, wastewater and human urine samples.     

Highly Selective and Sensitive Membrane Sensors for Copper(II) Ion Based on a New Benzo‐Substituted Macrocyclic Diamide 6,7,8,9,10‐Hexahydro‐2H‐1,13,4,7,10‐benzodioxatriazacyclopentadecine‐3,11(4H,12H)‐dione

Novel PVC membrane (PME) and coated graphite (CGE) Cu²⁺‐selective electrodes based on 5,6,7,8,9,10‐hexahydro‐2H‐1,13,4,7,10‐benzodioxatriazacyclopentadecine‐3,11(4H,12H)‐dione are prepared. The electrodes reveal a Nernstian behavior over wide Cu²⁺ ion concentration ranges (1.0×10^?7–1.0×10^?1 M for PME and 1.0×10^?8–1.0×10^?1 M for CGE) with very low limits of detection (7.8×10^?8 M for PME and 9.1×10^?9 M for CGE). The potentiometric responses are independent of the pH of the test solutions in the pH range 2.7–6.2. The proposed electrodes possess very good selectivities for Cu²⁺ over a wide variety of the cations including alkali, alkaline earth, transitions and heavy metal ions. The practical utility of the proposed electrodes have been demonstrated by their use in the study of interactions between copper ions and human growth hormone (hGH) in biological systems, potentiometric titration of copper with EDTA and determination of copper content of a sheep blood serum sample and some other real samples.     

Novel Cross‐Linked Films Prepared from Hyperbranched Poly(amine‐ester)

Summary: Novel hyperbranched poly(amine‐ester) (HPAE) cross‐linked films were prepared by cross‐linking the terminal hydroxyl groups of HPAE using glutaraldehyde (GA). Atom force microscope and scanning electron microscope revealed their smooth surfaces, dense and homogenous matrices. Property characterizations indicated that these cross‐linked films had good hydrophilicity, relative low protein adsorption, and high tensile strength. Also, their swelling behavior varied with the solvent.

Structure of the hyperbranched poly(amine‐ester).