| Abstract
| - This paper is a first comprehensive study on the correlated ion transport mechanisms contributing to theoverall conductivity behavior in a new class of poly(ethylene oxide)−polyurethane/polyacrylonitrile (PEO−PU/PAN) semi-interpenetrating polymer networks (semi-IPNs)−salt complex polymer electrolytes. Asimultaneous investigation of the electrical response on PEO−PU/PAN/LiClO4 and PEO−PU/PAN/LiCF3SO3semi-IPNs with varying EO/Li mole ratios (100, 60, 30, 20, 15, 10) has been carried out by impedancespectroscopy. Analysis of the complex plane and spectroscopic plots indicated the presence of two microscopicphases corresponding to the PEO−PU and PAN domains, which leads to space charge polarization in thesesystems. A suitably modified approach based on the universal power law (UPL) considering the independentcontribution from the individual microphases of semi-IPNs facilitates a complete interpretation of thespectroscopic profiles for the real component of conductivity (σ‘(ω)). The σ‘(ω) spectroscopic profiles werefitted with two power law equations, where the frequency region up to ∼300 kHz is the conductivity profileassociated with the PAN phase and beyond this is the superimposed contribution of the PEO−PU phase.Simulated fits using the UPL equation revealed two relaxation times (τPEO-PU, τPAN) related to ionic hoppingin the PEO−PU and PAN phases in addition to the conductivity relaxation time (τpeak) determined from theDebye peaks. The respective power law exponents (nPEO-PU ∼ 0.5−0.8, nPAN ∼ 1.0−1.6) indicate that thoughcationic hopping in the softer PEO−PU phase is favored, anionic hopping in the PAN phase contributessignificantly to the charge transport processes in these semi-IPNs. Correlation of the experimental resultswith the simulated fits enable us to distinguish the effects of semi-IPN composition, temperature, morphology,ion−ion, and ion−polymer interactions, which influence the microscopic molecular events, involved in thecharge transport in these complex semi-IPN polymer electrolytes.
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