Effects of PEG plasticizer concentrations and film preparation methods on the structural, dielectric and electrical properties of PEO–PMMA blend based plasticized solid polymer electrolyte films

Low molecular weight poly(ethylene glycol) (PEG) has been used as plasticizer in the preparation of plasticized solid polymer electrolyte (PSPE) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend based matrix with lithium tetrafluoroborate (LiBF4) as dopant ionic salt. Solution cast (SC) melt–pressed and the ultrasonic-microwave (US–MW) irradiated solution cast melt–pressed methods have been used for the preparation of these PSPE films. The dielectric dispersion, ac ionic conductivity and structural dynamics of these electrolytes have been studied by employing the dielectric relaxation spectroscopy (DRS) over the frequency range from 20 Hz to 1 MHz, at room temperature. The structural properties of these materials have been characterized by their X–ray diffraction (XRD) measurements. The influence of varying PEG concentrations (5, 10 and 15 wt%) and also the sample preparation methods on the complex dielectric function, ac electrical conductivity, electric modulus and the impedance spectra of these electrolytes have been explored. The ionic conductivity of US–MW prepared PSPE films enhances non-linearly, whereas for the SC prepared films it vary anomalously with the increase of PEG concentrations. The variations in conductivity of these PSPEs are governed by the change in strength of polymer-ion, plasticizer-ion and the polymer-plasticizer interactions and also the polymer chain segmental motion in the solid ion-dipolar complexes. Room temperature ionic conductivity values of the PEG concentrations and sample preparation methods dependent these PSPE electrolytes at low concentration of dopant salt are found in the range from 1.79 to 4.22 mS cm–1, which confirm their suitability in preparation of the all-solid-state ion conducting devices

Multiphysics Experimental Approaches for Insight into the Hydrogen Bonded Structures of Ethylene Glycol and Glycerol Mixtures toward Green Solvent Technology

Alcohols and their mixtures are credited most important polar solvents for advances in pharmaceutical, chemical,biological, thermal, and material technologies. A rigorous study for the characterization of hydrogen bonded heterogeneousintermolecular structures that formed in a mixed solvent based on alcohols containing two and three hydroxyl groupsmolecules is crucial to specific technological and industrial applications. Hence, in this work, the multiphysics experimentalapproaches including the measurements of dielectric, electrical, viscous, acoustic, thermal, and optical properties are appliedand analyzed to confirm the behaviour of hydrogen bonded molecular structures of ethylene glycol (EG; dihydric alcohol)with glycerol (Gl; trihydric alcohol) over the entire concentration range of EG+Gl mixtures at 298.15 K. The static dielectricpermittivity, direct current electrical conductivity, low frequency relaxation time, and refractive index values of the EG+Glmixtures are reported. Additionally, dynamic viscosity, density, ultrasound velocity, adiabatic compressibility,intermolecular free length, acoustic impedance, free volume, Rao’s constant, Wada constant, and viscoacoustic relaxationtime of the EG+Gl mixtures are determined, and also explored their significance to these alcohols molecular interactions.Ultraviolet-visible range absorbance behaviour of the alcohol mixtures is characterized in detail and confirmed theelectronic transitions at higher energy ultraviolet radiations. The detailed analysis of all the experimental results along withthe consideration of excess properties evidenced the formation of heterogeneous intermolecular hydrogen bonded structuresin these Newtonian-type alcohols mixtures. A small to adequate variation in the thermodynamical and other investigatedproperties with the concentration variation showed that the EG+Gl mixture can be optimized as a green solvent according tothe prerequisite properties for huge advances in soft condensed matter technologies

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinylpyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

92-102Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinyl pyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail

Optical characterization of different oxide nanomaterials dispersed PVA/PEO blend matrix-based hybrid polymer nanocomposites for advances in optoelectronic device technologies

693-700Optical properties of different oxide nanomaterials (viz. zinc oxide (ZnO), tin oxide (SnO2), silica (SiO2), and alumina (Al2O3)) as nanofillers (NFs) and a host polymer matrix of poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend based hybrid polymer nanocomposites (HPNCs) have been investigated by employing ultraviolet-visible (UV-Vis) spectroscopy. The UV-Vis absorbance spectra over the photons wavelength range 200-800 nm, and the absorption coefficient, energy bandgap, and Urbach energy of the PVA/PEO/NFs HPNC films are determined and reported. The dependence of the optical characteristics of these HPNCs on the type of oxide nanofillers and their concentration have been studied which is found correlated with the optical properties of the nanofillers. Considering the results, suitability of PVA/PEO/NFs materials as potential candidates for UV-shielder, light diffuser, bandgap tuner, and photo-sensor/detector in the design and evolution of various flexible-type optoelectronic devices/components have been discussed

Influence of SnO2 nanoinclusions on the structural and dielectric properties of (PVA–PEO)/SnO2 nanocomposites

367-374Nanofiller concentration dependent, tunable-type structural, dielectric, thermo-mechanical, and optical properties of the polymer nanocomposites (PNCs) have established them as technologically smart multifunctional materials for advances in stretchable and flexible-type organoelectronic, optoelectronic, and energy harvesting/storage devices. In this work, organic-inorganic hybrid PNC films comprising poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blend as host matrix (PVA–PEO; 50–50 wt%) dispersed with varying concentration of tin oxide (SnO2) nanoparticles up to 5 wt% have been prepared by the solution-cast method. The influence of SnO2 loading on the percent crystallinity of the host matrix and the structural parameters of the PEO crystallites has been examined by the X-ray diffraction (XRD) measurements of the PNC films. The results reveal that the percent crystallinity of the semicrystalline (PVA–PEO) matrix gradually enhanced, whereas the interlayer spacing, crystallite size, and interchain separation of the PEO crystallites varied anomalously with the increase of SnO2 concentration in the PNC films. The complex dielectric permittivity, alternating current (ac) electrical conductivity, and electric modulus dispersion over the broad frequency range (20 Hz–1 MHz) of these (PVA–PEO)/SnO2 films has been characterized by employing the dielectric relaxation spectroscopy (DRS). It has been observed that 1 wt% SnO2 nanoinclusion abruptly reduced the interfacial, dipole polarizations, and also electrical conduction of the host matrix, whereas considerably enhanced hindrance to the PEO chain segmental motion studied at 30 °C. The temperature dependent study (30–60 °C) of the representative PNC film of 3 wt% nanofiller reveals its thermally activated non-linear dielectric polarization at fixed frequency and also Arrhenius behaviour of the dielectric relaxation processes of significantly low activation energy (≃ 0.14 eV). The structural, dielectric, and electrical properties of the (PVA–PEO)/SnO2 films have been critically analyzed for their suitability as controllable low dielectric permittivity polymer nanodielectric (PNDs) materials for biodegradable electronic devices

Dielectric dispersion and electrical conductivity of amorphous PVP–SiO2 and PVP–Al2O3 polymeric nanodielectric films

201-209The biodegradable hybrid polymer nanocomposite (PNC) films comprising silica (SiO2) and alumina (Al2O3) nanoparticles as inorganic nanofillers and the poly(vinyl pyrrolidone) (PVP) as organic host matrix (i.e., PVP–x wt% SiO2 and PVP–x wt% Al2O3 for x = 0, 1, 3 and 5) have been prepared by aqueous solution-casting method. X-ray diffraction (XRD) study reveals that these nanocomposite materials are highly amorphous. The dielectric spectroscopy of these different nanofiller concentrations PNC films has been carried out in the frequency range from 20 Hz to 1 MHz at a fixed temperature and also for 3 wt% nanofillers containing PNC films with the temperature variation. The results confirm that the complex dielectric permittivity of these hybrid films is influenced by the interfacial polarization in the low frequency range of 20 Hz to 1 kHz, whereas in the high frequency range up to 1 MHz permittivity is mainly governed by the molecular polarization and remains almost independent of the frequency. These SiO2 and Al2O3 nanofillers containing PNC films at fixed temperature display anomalous behaviour of dielectric permittivity and ac electrical conductivity with the increase of nanofiller concentration, but these parameters significantly enhance at low frequencies with the increase of temperature of the films. The electric modulus spectra of Al2O3 containing PNC film exhibit relaxation peaks below 100 Hz at higher temperatures which attribute to the interfacial polarization relaxation process. The frequency independent dielectric permittivity and significantly low loss of these PNC materials at radio frequencies confirm their suitability as polymeric nanodielectric (PND) substrate and insulator in the design and fabrication of biodegradable electronic devices and electrical components

Effectively polymer composition controllable optical properties of PVDF/PMMA blend films for advances in flexible device technologies

169-180Polymer blends and their matrices-based nanocomposites have been established as potential candidates in the advancement of optoelectronic and microelectronic device technologies because they bear attractive design flexibility and also tunable optical and dielectric properties. In this research, we prepared the poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blend films with varying constituents concentration (viz. PVDF/PMMA=100/0, 80/20, 60/40, 40/60, 20/80, 0/100 wt/wt%), and these were investigated by employing ultraviolet-visible (UV-Vis) spectrophotometer for their in-detail optical characterization. The absorbance, reflectance, and transmittance spectra of these PVDF/PMMA blend films in the wavelength range from 200 nm to 800 nm were analyzed and considered to determine the values of various optical parameters. Due to significant differences in optical behaviour of the PVDF film and that of the PMMA film, the values of the direct energy band gap, extinction coefficient, refractive index, single oscillator energy, dispersive energy, optical range complex dielectric permittivity, optical conductivity, linear susceptibility, third-order non-linear susceptibility, and non-linear refractive index of the PVDF/PMMA blend films were found appreciably blend composition controllable. The energy bandgap, refractive index, and extinction coefficient of these materials are found in the ranges 5.42 to 4.93 eV, 2.22 to 1.72, and 6.62 104 to 0.64 104, respectively. The experimental results offer a new paradigm for the use of these materials in the design and development of next-generation flexible optoelectronic and allied devices