Impedance spectroscopy of polyaniline coated hydrogel

Novel SPEEK-ZIF-67 Proton Exchange Nanocomposite Membrane for PEMFC Application at Intermediate Temperatures

“…The dielectric loss spectra can be modeled by a piecewise function given as where Δε = ε EP – ε ∞ is the dielectric strength until the electrode polarization (EP) is fully developed, where ε ∞ is the static permittivity, ε EP is the dielectric permittivity at EP, τ is the Cole–Cole relaxation time, σ is the conductivity associated with the protons of the composite membrane, and α represents the broadness of the relaxation, being equal to 1 for a Debye-type relaxation and usually taking values between 0.5 and 0.9 for proton-conducting polymers, where charge motion is promoted by a hopping mechanism, since the different interactions among protons and polymer hopping sites generates a wider distribution of relaxation time . σ′ is conductivity related with the conductivity of mobile charges associated with other types of ions such as impurities, and ε 0 is the corresponding vacuum dielectric permittivity.…”

“…In the original Debye model, this relaxation is characterized by a single relaxation time (τ) that depends on temperature, but the local restrictions imposed to the mobility of dipoles for their immediate surroundings in the polymer membrane result in a distribution of relaxation times that can be taken into account by the Cole−Cole model, which uses a relaxation time distribution (τ), which is in this case the central relaxation time of this distribution and depends on sample thickness, temperature, and type of polymer 63−66 The dielectric loss spectra can be modeled by a piecewise function given as where Δε = ε EP − ε ∞ is the dielectric strength until the electrode polarization (EP) is fully developed, where ε ∞ is the static permittivity, ε EP is the dielectric permittivity at EP, τ is the Cole−Cole relaxation time, σ is the conductivity associated with the protons of the composite membrane, and α represents the broadness of the relaxation, being equal to 1 for a Debyetype relaxation and usually taking values between 0.5 and 0.9 for proton-conducting polymers, where charge motion is promoted by a hopping mechanism, since the different interactions among protons and polymer hopping sites generates a wider distribution of relaxation time. 67 σ′ is conductivity related with the conductivity of mobile charges associated with other types of ions such as impurities, and ε 0 is the corresponding vacuum dielectric permittivity.…”

Functional Materials Made by Combining Hydrogels (Cross-Linked Polyacrylamides) and Conducting Polymers (Polyanilines)—A Critical Review

“…In situ polymerization of anilines inside cPAM (ISP) is very simple to implement and is the most extensively used method to combine PANIs and cPAM [ 45 , 46 , 47 , 48 ]. The hydrogel is formed by radical polymerization of an acrylamide (or acrylic acid) in the presence of a crosslinker (a compound bearing two vinyl groups in the same molecule).…”

Surface Modification of Nanofiltration Membranes by Interpenetrating Polymer Networks and Their Evaluation in Water Desalination

“…The loading plot of PC 2 (17% of explained variance) shows wavenumbers of full aromatic polyamide layer at 1669, 1609, and 1542 cm −1 , associated with C�O amide I stretching, aromatic amide C�C bending, and N−H amide II bending, respectively (Figure 4d). 28 The loading plot of PC 3 includes bands associated with APSA (1147 and 1040 cm −1 , assigned to S�O asymmetric and symmetric stretching, respectively 29,30 ) and ClAPTA (1482 cm −1 , assigned to −N(CH 3 ) + 30,31 ) (Figure 4e). Bands associated with membranes modified with GMA-NMG were not detected by the PCA, probably because the polymer do not add functional groups on the surface.…”