Effect of p‐toluenesulfonate on inhibition of overoxidation of polypyrrole

Abstract

Electrochemically synthesized polypyrrole (PPy) films degrade under anodic polarization in aqueous solution. PPy is irreversibly oxidized leading to subsequently to an insulating material. This article highlights the degradation behavior of electrochemically synthesized PPy films using inorganic (perchlorate, ClO 4 À ), organic (p-toluenesulfonate, pTS À ) and mixed (inorganic-organic,anions systems in aqueous solution. The PPy films were subject to overoxidation by means of anodic polarization for a certain period of time and consecutively cyclic voltammetry and electrochemical impedance spectroscopy were employed to investigate the influence of anions used during polymerization on the stability and redox activity of the polymer. The modification in the surface morphology of PPy films due to the application of anodic polarization distinctively shows the effect of degradation at polymer/electrolyte interface. The presence of organic anion in the system (PPy/pTS and PPy/mixed) has shown improved electrochemical activity and is stable to electrochemical degradation for a longer period of time than PPy/ClO 4 À .

Positron lifetime study of PAN‐based carbon fiber‐reinforced polymer composites

“…3a and b, it is clear that o-Ps lifetime (s 3 ) increases and o-Ps intensity (I 3 ) decreases upon PAN-CF loading into PBT matrix. This is probably due to the formation of bigger free volume holes due to coalesce of smaller ones [37]. In addition, the inhibition of positronium formation upon PAN-CF loading cannot be ruled out [38].…”

Effect of hydrodynamic interaction on free volume changes and the mechanical properties of SGFR‐PBT composites

“…Positron Annihilation Lifetime Measurements. Positron annihilation lifetime spectra of PBT matrix and short glass fiber reinforced polybutylene terephthalate (SGFR-PBT) composites for different fiber concentration were recorded using a standard fast-fast coincidence system with conically shaped BaF 2 scintillators coupled to photomultiplier tubes of type XP2020/Q with quartz window as detectors [8]. The coincidence lifetime spectrometer had a resolution of 220 ps.…”

“…The spectrometer was operated at 220 ps and all lifetime measurements were performed at room temperature. Two to three positron lifetime spectra with more than a million counts under each spectrum were recorded in a time of 2-4 h [8]. Consistently reproducible spectra were analyzed into three lifetime components with the help of the computer program PATFIT-88 [15] with proper source and background corrections.…”

“…The microstructural characterization of SGFR-PBT composites has been performed by one of the well-established, sophisticated tools viz., Positron Annihilation lifetime Spectroscopy (PALS). In recent years, positron lifetime technique has emerged as a unique and potent probe for directly characterizing the free volume cavities and their concentration in the amorphous region of the polymers in terms of positron lifetime of the injected positrons [8]. The free volume holes provide pathways for thermal motion of the chain segments.…”

Synthesis and characterization of secondary doped polypyrrole/organic modified attapulgite conductive composites

“…Recently, conducting polymers have attracted increasingly growing attention in material science. Among them, PPy has been broadly used in electronic devices, biomedical tests, and chemical sensors for its good conductivity as well as thermal and light stability in air atmosphere. However, its conductivity, as any other eigenstates conductive polymers, is still rather low for the further ultilization .…”