Gas sensing property of a conducting copolymer

A bifunctional amido thiophene, namely hexamethylene (bis-3-thiophene acetamide) (HMTA) was synthesized and its copolymer with pyrrole was electrochemically prepared in water/PTSA solvent/electrolyte medium. Sensory behavior of this copolymer against ammonia, methanol, dichloromethane (DCM) and n-hexane vapors was investigated. The methanol vapor, which can form hydrogen bonds with the polar groups on the copolymer surface, showed the maximum response. DCM, which is less polar, yielded relatively lower response than methanol. Hexane, being the non-polar vapor, showed the lowest response

Long Wavelength Photosensitizers for Diaryliodonium Salts Based on the 2-Benzyl-2H-benzo[d][1,2,3]triazole Skeleton

Two benzotriazole derivatives, 2-benzyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3] triazole (BBTS) and 2-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b][1,4] dioxin-5-yl)-2H-benzo[d] [1,2,3] triazole (BBTES) were employed as photosensitizers for diaryliodonium salt photoinitiators in photoinitiated cationic polymerization of various epoxide and vinyl ether monomers. Diphenyliodonium hexafluorophosphate (Ph2I+PF6-) salt was used as the photoinitiator in this study. Extended conjugation and electron-rich moieties of the photosensitizers enabled the use of long wavelength UV and visible light emitting light sources in cationic photopolymerizations. Having low oxidation potentials and good solubility in cationically polymerizable monomers make them efficient photosensitizers for the diphenyliodonium salt in the photoinitiated cationic polymerization. Polymerizations were achieved at room temperature and monitored by optical pyrometry. Moreover, photopolymerization of a diepoxide monomer with ambient solar irradiation in the presence of BBTES and BBTS were examined

A soluble conducting polymer of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole and its electrochromic device

A monomer 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole was synthesized via reaction of 1,4-di(2-thienyl)-1,4-butanedione and p-toluidine in the presence of catalytical amount of p-toluenesulfonic acid. Chemical polymerization of the monomer yielded a soluble polymer. The average molecular weight was determined by gel permeation chromatography as number average molecular weight (Mn) 2.5 x 10(3) g/mol. The monomer was also electrochemically polymerized in the presence of LiClO4, NaClO4 (1:1) as the supporting electrolyte in acetonitrile. Cyclic Voltammetry, Fourier Transform Infra Red, Nuclear Magnetic Resonance, Scanning Electron Microscopy and Ultraviolet-Visible Spectroscopy were employed for the characterization of the polymer. Spectroelectrochemistry analysis of homopolymer revealed an electronic transition at 428 nm which corresponds to pi-pi* transition. Switching ability of the homopolymer was evaluated by kinetic studies upon measuring the percent transmittance (%T) at the maximum contrast point, indicating that poly(2,5-di(thiophen-2-yl)-l-p-tolyl-IH-pyrrole) is a suitable material for electrochromic devices

Immobilization of Invertase in Copolymer of 2,5-Di(thiophen-2-yl)-1-p-Tolyl-1H-Pyrrole with Pyrrole

Immobilization of invertase in conducting copolymer matrix of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole with pyrrole (poly(DDTP-co-Py)) was achieved via electrochemical polymerization. Kinetic parameters, Michaelis-Menten constant, Km and the maximum reaction rate, Vmax were investigated. Operational stability and temperature optimization of the enzyme electrodes were also examined. Immobilized invertase reveals maximum activity at 50 degrees C and; pH 8 and pH 4 for two copolymer matrices. Although the same two monomers are utilized for the copolymer synthesis, the way the copolymer is produced results in quite different responses in terms of enzyme activity, optimum pH and kinetic parameters. Excellent operational stability of the enzyme electrodes enables their repetitive use in the determination of invert sugar

Electrochromic properties of a novel low band gap conductive copolymer

A copolymer of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole (DTTP) with 3,4-ethylene dioxythiophene (EDOT) was electrochemically synthesized. The resultant copolymer P(DTTP-co-EDOT) was characterized via cyclic voltammetry, FTIR, SEM, conductivity measurements and spectroelectrochemistry. Copolymer film has distinct electrochromic proper-ties. It has four different colors (chestnut, khaki, camouflage green, and blue). At the neutral state; gimel(max) due to the pi-pi* transition was found to be 487 nm and E-g was calculated as 1.65 eV. Double potential step chronoamperometry experiment shows that copolymer film has good stability, fast switching time (less than 1 s) and good optical contrast (20%). An electrochromic device based on P(DTTP-co-EDOT) and poly(3,4-ethylenedioxythiophene) (PEDOT) was constructed and characterized. The device showed reddish brown color at -0.6 V when the P(DTTP-co-EDOT) layer was in its reduced state; whereas blue color at 2.0 V when PEDOT was in its reduced state and P(DTTP-co-EDOT) layer was in its oxidized state. At 0.2 V intermediate green state was observed. Maximum contrast (%Delta T ) and switching time of the device were measured as 18% and 1 s at 615 nm. ECD has good environmental and redox stability

Benzyl substituted benzotriazole containing conjugated polymers: Effect of position of the substituent on electrochromic properties

New classes of EDOT coupled-benzotriazole bearing pi-conjugated monomers containing benzyl units on electron-withdrawing benzotriazole moiety were synthesized. The effect of structural differences on electrochemical and optoelectronic properties of the resulting polymers (PBBTES and PBBTEA) was investigated. The results showed that the insertion of benzyl substituent to benzotriazole from different positions changes the electronic structure of polymer which results in completely different electrochemical and optical properties. PBBTES has a very low oxidation potential (0.13V) compared to the oxidation potential of PBBTEA (0.98 V). Spectroelectrochemical analyses revealed that PBBTES is blue in its neutral state with a pi-pi* transition at 625 nm whereas PBBTEA is orange in its neutral state with a pi-pi* transition at 477 nm. The band gap (E(g)) values for PBBTES and PBBTEA were calculated as 1.48 eV and 1.57 eV, respectively. PBBTEA can be switched between blue neutral state and light blue oxidized state while PBBTEA reveals orange color at the neutral state and gray color at oxidized state

Multichromic polymers of benzotriazole derivatives: Effect of benzyl substitution

Two electroactive monomers 1-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3]triazole (BBTA) and 2-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3]triazole (BBTS) were synthesized with satisfactory yields. The effect of substitution site on electrochemical and optical properties was investigated with cyclic voltammetry and spectroelectrochemical studies. Results showed that position of pendant group alters the electronic structure of the resulting polymer causing different optical and electrochemical behaviors. Symmetrically positioned benzyl unit on benzotriazole moiety resulted in a neutral state red polymer. PBBTS, having multi-colored property in its different oxidized and reduced states. Its analogue PBBTA exhibited maximum absorption at 390 nm in its neutral state and also revealed multicolored electrochromic property upon stepwise oxidation. Very different optical band gap values were calculated: 1.55 eV and 2.25 eV for PBBTS and PBBTA, respectively

Recent advances in the synthesis and applications of inorganic polymer

Polymers are ubiquitous in modern society. They are used in a variety of appli-cations, ranging from sophisticated - such as electronics - to relatively simple ones like packaging. Inorganic polymers often have certain advantages over their organic counterparts-such as increased thermal stability and unique material properties - and have been an active area of research for many years. The potential technological applications that are imagined for some of these polymers, however, have mostly failed to be realized. This article aims to examine some of the advances in the general field of inorganic polymers, which have been made in the last three years. We also attempted to ascertain whether the promise of these materials will be realized in the near future, especially as advanced polymeric materials