A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo and electrochemical control

An electroactive nitrospiropyran-substituted polyterthiophene, 2-(3,3′′-dimethylindoline-6′-nitrobenzospiropyranyl)ethyl 4,4′′-didecyloxy-2,2′:5′,2′′-terthiophene-3′-acetate, has been synthesized for the first time. The spiropyran, incorporated into the polymer backbone by covalent attachment to the alkoxyterthiophene monomer units, leads to multiple coloured states as a result of both electrochemical isomerization of the spiropyran moiety to merocyanine forms as well as electrochemical oxidation of the polyterthiophene backbone and the merocyanine substituents. While electrochemical polymerization of the terthiophene monomer could occurs without the apparent oxidation of the spiropyran, the subsequent electrochemistry is complex and clearly involves this substituent. In order to understand this complex behaviour, the first detailed electrochemical study of the oxidation of the precursor spiropyran, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6’-nitrobenzospiropyran, was undertaken, showing that, in solution, an irreversible electrochemical oxidation of the spiropyran occurs leading to reversible redox behaviour of at least two merocyanine isomers. With these insights, an extensive electrochemical and spectroelectrochemical study of the nitrospiropyran-substituted polyterthiophene films reveals an initial irreversible electrochemical oxidative ring opening of the spiropyran to oxidized merocyanine. Subsequent reduction and cyclic voltammetry of the resulting nitromerocyanine-substituted polyterthiophene film gives rise to the formation of both merocyanine π-dimers or oligomers and π-radical cation dimers, between polymer chains. Although merocyanine formation is not electrochemically reversible, the spiropyran can be photochemically regenerated, at least in part, through irradiation with visible light. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerizes to the planar merocyanine moiety affording a smoother polymer film. The conductivity of the freestanding polymer film was found to be 0.4 S cm-1

Electrochemical removal of phenol in alkaline solution. Contribution of the anodic polymerization on different electrode materials

The removal of organic pollutants based on electropolymerization on an anode was performed in the case of phenol in alkaline solution. The polymer formed by a process involving less than two electrons per molecule of phenol, is then precipitated by decreasing the pH and finally filtered and disposed. The electrochemical polymerization of phenol (C0 = 0.105M) in alkaline solution (pH = 13) at 86 ◦C has been studied by galvanostatic electrolysis, using a range of anode materials characterized by different O2-overpotentials (IrO2, Pt and B-PbO2). Measurements of total organic carbon and HPLC have been used to follow phenol oxidation; the morphology of the polymer deposited on the electrode surface has been examined by SEM. Experimental data indicate that phenol concentration decreases by oxidation according to a first order reaction suggesting a mass transport limitation process. Polymeric films formed in alkaline solution did not cause the complete deactivation of the anodes. SEM results show that the polymeric films formed on Ti/IrO2 and Pt anodes cannot be mineralized. On the other hand, complex oxidation reactions leading to the partial incineration of polymeric materials can take place on the Ta/B-PbO2 surface due to electrogenerated HO• radicals which have an oxidizing power much higher than that of intermediaries formed respectively on IrO2 and Pt. It is assumed that the polymer films formed on these anodes have different permeability characteristics which determine the rate of mass transfer of the phenol. The fractions of phenol converted in polymers were 25, 32 and 39% respectively with Ti/IrO2, Pt and Ta/B-PbO2, a series of materials in which the O2-overvoltage increases

The mathematical description of the electrosynthesis of composites of oxy-hydroxycompounds cobalt with polypyrrole overooxidazed

The electrosynthesis of the composite with of the overoxidized polypyrrole with cobalt oxy-hydroxide in strongly acidic media has been described mathematically, using linear stability theory and bifurcation analysis. The steadystates stability conditions and oscillatory and monotonic instability requirements have been described too. The system´s behavior was compared with behavior of other systems with overoxidation, electropolymerization of heterocyclic compounds and electrosynthesis of the cobalt oxy-hydroxides

Al/PANI-MWNT/Au-Plastic Schottky Diode Solar Cells

Al/PANI-MWNT/Au-Plastic Schottky diode solar cells were fabricated by the electrochemical polymerization technique to make polyaniline films on the top of gold nanoparticles film. The aluminum contact was deposited by thermal evaporation. The electro-optical characteristics of these devices produced at the different polymerization time were compared. Here, we achieved the highest ever reported open-circuit voltage of 0.8 V with the electrochemical polymerization technique. The polymerization of polyaniline films was thought to be a major factor in the enhanced performance. The effects of varying the polyaniline thickness on the device performance were investigate

Electrochemical Polymerization of Aniline

In recent years, great focus has been placed upon polymer thin films. These polymer thin films are important in many technological applications, ranging from coatings and adhesives to organic electronic devices, including sensors and detectors. Electrochemical polymerization is preferable, especially if the polymeric product is intended for use as polymer thin films, because electrogeneration allows fine control over the film thickness, an important parameter for fabrication of devices. Moreover, it was demonstrated that it is possible to modify the material properties by parameter control of the electrodeposition process. Electrochemistry is an excellent tool, not only for synthesis, but also for characterization and application of various types of materials. This book provides a timely overview of a current state of knowledge regarding the use of electropolymerization for new materials preparation, including conducting polymers and various possibilities of applications

Nanostructured Conductive Polymers for Advanced Energy Storage

Conductive polymers combine the attractive properties associated with conventional polymers and unique electronic properties of metals or semiconductors. Recently, nanostructured conductive polymers have aroused considerable research interest owing to their unique properties over their bulk counterparts, such as large surface areas and shortened pathways for charge/mass transport, which make them promising candidates for broad applications in energy conversion and storage, sensors, actuators, and biomedical devices. Numerous synthetic strategies have been developed to obtain various conductive polymer nanostructures, and high-performance devices based on these nanostructured conductive polymers have been realized. This Tutorial review describes the synthesis and characteristics of different conductive polymer nanostructures; presents the representative applications of nanostructured conductive polymers as active electrode materials for electrochemical capacitors and lithium-ion batteries and new perspectives of functional materials for next-generation high-energy batteries, meanwhile discusses the general design rules, advantages, and limitations of nanostructured conductive polymers in the energy storage field; and provides new insights into future directions.University of Texas at Austin3M Non-tenured Faculty awardWelch Foundation F-1861Materials Science and Engineerin

Design of a polyaniline based biosensor electrode for glucose: A comparative study of two immobilized systems

The present study compares the results of two different methods employed for preparation of polyaniline based glucose biosensor with respect to enzyme loading, biosensing efficiency and potential stability. Kinetic analysis of the potentiometric data for two enzyme immobilized electrode systems show that the GOx/PANI electrode is suitable for assaying samples with low analyte concentrations, whereas the GOx/m-ABA/PANI electrode system exhibits a better potential stability. It may therefore be possible to achieve high level of biosensing efficiency by chemical modeling and synthesis combined with careful selection of the immobilization method

Electrochemical Polymerization of Thiophene Derivatives attached to Lead Sulfide Nanoparticle

Polythiophene has proven to be an excellent conductive polymer, and has been thouroughly researched over the past decade. Because of its conjugated backbone, it has gained popularity in photovoltaic cells as both n and p-type materials. Thiophene based derivatives: 3-(5-bromopentyl)thiophene, 5-(3\u27-thienyl)pentanoic acid (53TPA), 5- {3\u27-thienyi)-1mercaptopentane (53T1MP), and both 53TPA and 53T1MP capped PbS nanparticies were electrochemically polymerized with varying ratios of 2,2\u27-bithiophene y onto an ITO working electrode. Resulting polymer films were characterized with cycliccoltammetry, and insoluable and soluable films were characterized using FTIR and NMR respectively

Immobilization of invertase in conducting polymer matrices

Cataloged from PDF version of article.This paper reports a novel approach in the electrode immobilization of an enzyme, invertase, by electrochemical polymerization of pyrrole in the presence of enzyme. The polypyrrolelinvertase and polyamide/polypyrrole/invertase electrodes were constructed by the entrapment of enzyme in conducting matrices during electrochemical polymerization of pyrrole. This study involves the preparation and characterization of polypyrrole/invertase and polyamidelpolypyrrolelinvertase electrodes under conditions compatible with the enzyme. It demonstrates the effects of pH and temperature on the properties of enzyme electrode. Enzyme leakage tests were carried out during reuse number studies. The preparation of enzyme electrodes was done in two different electrolyte/ solvent systems. The enzyme serves as a sucrose electrode and retains its activity for several months. (c) 1997 Elsevier Science Limited. All rights reserve

Elektrohemijska sinteza elektroprovodnih polimera

Electroconducting polymers from the group of synthetic metals are extensively investigated due to numerous properties perspective in practical application. These materials may be synthesized by both chemical and electrochemical procedures. Chemical synthesis is suitable when bulk quantities of the polymer are necessary and up to date it presents dominant commercial method of producing electroconducting polymers. Nevertheless, the electrochemical synthesis has its advantages; it avoids usage of oxidants since conducting polymeric material is obtained at anode upon application of positive potential, leading to increased purity. On the other hand, since the polymer is deposited onto electrode, further electrochemical characterization is facilitated. Owing to actuality of the research in the field, this text aims to describe important aspects of electrochemical synthesis of electroconducting polymers, with special emphasis to polyaniline and polypyrrole.Tradicionalno shvatanje o polimerima kao odličnim izolatorima izmenjeno je sedamdesetih godina prošlog veka kada su naučnici uspeli da sintetizuju poiliacetilen čija je provodljivost bila bliska metalnoj. Ova činjenica ukazala je na novo svojstvo polimernih materijala i lansirala potpuno novo multidisciplinarno naučno polje, popularno nazvano, sintetički metali. Iako je danas pojmom elektroprovodnih polimera obuhvaćena velika grupa jedinjenja koja su klasifikovana prema prirodi prenosioca naelektrisanja, naziv elektroprovodni polimeri se najčešće koristi u literaturi upravo za polimerne materijala iz grupe sintetičkih metala koji poseduju elektronsku provodljivost kao posledicu specifičnosti molekulske strukture. Pored zahteva molekulske structure, koja podrazumeva konjugovani sistem dvostrukih veza, za provodljivost elektroprovodnih polimera neophodno je dopovanje. Termin dopovanje, iako preuzet iz terminologije klasičnih neorganskih poluprovodnika, podrazumeva u mnogome drugačiji proces. Dopovanje elektroprovodnih polimera podrazumeva oksidaciju tokom koje se, u cilju održavanja elektroneutralnosti polimernog lanca, uvodi stehiometrijska količina jona (anjona). Terminom dopovanje obuhvaćena je i protonacija polimernog lanca kiselinom, u slučaju polianilina, a nedavno je potvrđena i u slučaju polipirola. Kako je, na ovaj način, uvedena velika količina jona izmenjenja je polazna struktura elektroprovodnog polimera, tako da svojstva nastalog materijala zavise u velikoj meri od svojstava dopanta. Iako su na početku razvoja ove oblasti, elektroprovodni polimeri bili sintetizovani hemijskim postupcima, sticanjem uvida u mehanizam hemijske sinteze koja podrazumeva oksidativnu radikalnu polimerizaciju, postalo je jasno da se ovi materijali mogu dobiti i elektrohemijskim postupcima. Elektrohemijska sinteza ima prednosti, pošto se polimer dobija oksidacijom na elektrodama (anodama), čime je izbegnuta upotreba oksidacinog sredstva i omogućena veća čistoća proizvoda. Sa druge strane, elektroprovodni polimer je u većini slučajeva dobijen u obliku prevlake na elektrodi, pa je njegova dalja karakterizacija elektrohemijskim tenikama olakšana. Interesovanje za oblst sinteze elektroprovodnih polimera ne jenjava, pa je ovaj tekst posvećen osnovnim principima elektrohemijskih postupaka sinteze sa posebnim osvrtom na najpopularnije elektroprovodne polimere, polianilin i polipirol