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R.J. Sengwa,Priyanka Dhatarwal,Shobhna Choudhary 한국물리학회 2015 Current Applied Physics Vol.15 No.2
Solid polymer electrolytes consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50:50 wt/wt%) with lithium triflate (LiCF3SO3) as a dopant ionic salt at stoichiometric ratio [EO + (C=O)]:Li+ = 9:1, poly(ethylene glycol) (PEG) as plasticizer (10 wt%) and montmorillonite (MMT) clay as nanofiller (3 wt%) have been prepared by solution cast followed by melt-pressing method. The Xeray diffraction study infers that the (PEO-PMMA)-LiCF3SO3 electrolyte is predominantly amorphous, but (PEO-PMMA)-LiCF3SO3-10 wt% PEG electrolyte has some PEO crystalline cluster, whereas (PEO-PMMA)-LiCF3SO3-10 wt% PEG-3 wt% MMT electrolyte is an amorphous with intercalated and exfoliated MMT structures. The complex dielectric function, ac electrical conductivity, electric modulus and impedance spectra of these electrolytes have been investigated over the frequency range 20 Hz to 1 MHz. These spectra have been analysed in terms of the contribution of electrode polarization phenomenon in the low frequency region and the dynamics of cations coordinated polymer chain segments in the high frequency region, and also their variation on the addition of PEG and MMT in the electrolytes. The temperature dependent dc ionic conductivity, dielectric relaxation time and dielectric strength of the plasticized nanocomposite electrolyte obey the Arrhenius behaviour. The mechanism of ions transportation and the dependence of ionic conductivity on the segmental motion of polymer chain, dielectric strength, and amorphicity of these electrolytes have been explored. The room temperature ionic conductivity values of the electrolytes are found ~10-5 S cm-1, confirming their use in preparation of allsolid- state ion conducting devices.
Shobhna Choudhary,R.J. Sengwa 한국물리학회 2018 Current Applied Physics Vol.18 No.9
Polymer nanocomposite (PNC) films based on the blend matrix of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) (50/50 wt%) incorporated with zinc oxide (ZnO) nanoparticles (i.e., (PVA–PVP)–x wt% ZnO; x=0, 1, 3 and 5) were prepared by solution-cast method. The behaviour of polymer-polymer and polymernanoparticle interactions in the PNC films was ascertained by employing X-ray diffraction, energy dispersive Xray, and Fourier transform infra-red spectroscopies. Scanning electron microscopy and atomic force microscopy were performed for the morphological characterization, whereas the thermal and optical properties of the PNC films were investigated by using differential scanning calorimetry and ultraviolet–visible spectroscopy, respectively. The dielectric and electrical behaviour of these PNC materials were determined by employing the dielectric relaxation spectroscopy over the frequency range from 20 Hz to 1 MHz. The influence of ZnO concentration on the degree of PVA crystalline phase and the crystallite size, surface morphology and roughness of the films, the glass phase transition and melting phase transition temperatures, direct and indirect optical energy band gap, refractive index, complex permittivity, electrical conductivity, activation energy and the structural dynamics of these PNC materials were explored. The investigated properties of the PNC films were credited to an innovation and engineering of novel high performance flexible nanodielectrics in the area of advanced functional materials for their promising applications especially in the next generation optoelectronic, gas sensor and microelectronic devices.