Broadband Dielectric Spectroscopy Research Articles

Critical-like behavior of low-frequency dielectric properties in compressed liquid crystalline octyloxycyanobiphenyl (8OCB) and its nanocolloid with paraelectric BaTiO3

The report presents pressure-related broadband dielectric spectroscopy (BDS) studies in liquid crystalline octyloxycyanobiphenyl (8OCB) and its nanocolloid with BaTiO3 paraelectric nanoparticles. It is focused on the low-frequency (LF) domain, and the impact of pretransitional fluctuations. Studies were carried out in isotropic liquid, nematic, Smectic A, and solid crystal phases. In each case, the critical-type behavior for the LF contribution to the real part of dielectric permittivity and DC electric conductivity is evidenced. Studies of dielectric constant, related to the static frequency domain, revealed in SmA mesophase the shift from the XY-type to the mean-field type criticality when adding nanoparticles. The ‘giant’ premelting effect, with the critical-like portrayal, in the solid crystal phase, is also evidenced. Studies are supplemented by the polarizing microscopy insight into all tested phases appearing on compressing in 8OCB, and the nanocolloid. Photos show prenematic fluctuations in the isotropic liquid phase, phase transitions, changes within nematic and smectic mesophases on compressing, and the impact of nanoparticles.

Pressure and temperature dependence of the electric modulus and loss factor of Poly(vinyl alcohol)/Poly(vinylidene fluoride) blends reinforced with Nano - Graphene platelets

Poly(vinyl alcohol)/Poly(vinylidene fluoride) blends reinforced with Nano - Graphene Platelets render piezoelectric by combining uniaxial plastic deformation end polarization. Comparative Broadband Dielectric Spectroscopy on fresh and piezoelectric specimens were carried oud at various temperature and hydrostatic pressure states. Dc conductivity, which results from inter-NGP fluctuation induced tunneling of electrons through the effective potential barrier set by the polymer, involves two charge transfer mechanisms. The shift of the glass transition temperature and the temperature triggering a kinetic process due to the enhancement of the mobility of water molecules bound to PVA, upon pressure are detected indirectly through associated changes to the conductivity modes. NGP filling induces a couple of interfacial charge trapping. Relaxations exhibit different thermodynamics and different dependencies for fresh and piezoelectric specimens on pressure. Hydrostatic compression of heterogeneous matter results in an inhomogeneous internal stress field, whereas stress is locally amplified. In PNC, small scale relaxation is disturbed by the spatial fluctuation of the internal stress field. Rendering the PVdF grains piezoelectric, local stress amplification induces fluctuations of the local electric field. Fluctuations (of the internal stress or electric field) affect rather a short-range charge relaxation, rather than macroscopic dc conductivity.

Ethaline and related systems: may be not “deep” eutectics but clearly interesting ionic liquids

Abstract Ethaline, the 1:2 molar ratio mixture of ethylene glycol (EG) and choline chloride (ChCl), is generally regarded as a typical type III deep eutectic solvent (DES). However, careful differential scanning calorimetry (DSC) of EG + ChCl mixtures surprisingly revealed that the liquidus lines of the phase diagram apparently follow the predictions for an ideal binary non-electrolyte mixture. Applying broad-band dielectric relaxation spectroscopy to room-temperature solutions of ChCl, and of the related salts choline iodide and chlorocholine chloride, in EG up to saturation, we explored the possible reasons for this conundrum. It appears that in these solutions free ions are rather scarce. Instead, contact ion pairs and larger aggregates predominate.

Broadband Dielectric Spectroscopy with a Microwave Ablation Antenna

Microwave ablation is a technique used to treat tumorous tissue. Its clinical use has been greatly expanding in the last few years. Because the design of the ablation antenna and the success of the treatment greatly depend on the accurate knowledge of the dielectric properties of the tissue being treated, it is highly valuable to have a microwave ablation antenna that is also able to perform in-situ dielectric spectroscopy. In this work, an open-ended coaxial slot ablation antenna design operating at 5.8 GHz is adopted from previous work, and its sensing abilities and limitations are investigated in respect of the dimensions of the material under test. Numerical simulations were performed to investigate the functionality of the floating sleeve of the antenna and to find the optimal de-embedding model and calibration option for obtaining accurate dielectric properties of the area of interest. Results show that, as in the case of the open-ended coaxial probe, the accuracy of the measurement greatly depends on the likeness between the calibration standards' dielectric properties and the material under test. Finally, the results of this paper clarify to which extent the antenna can be used to measure dielectric properties and paves the way to future improvements and the introduction of this functionality into microwave thermal ablation treatments.

Analysis of Selected Dielectric Properties of Epoxy-Alumina Nanocomposites Cured at Stepwise Increasing Temperatures

The paper presents the effects of gradual temperature curing on the dielectric properties of epoxy nanocomposite samples. Samples were prepared based on Class H epoxy resin filled with nano-alumina (Al2O3) for different wt% loadings (0.5 wt% to 5.0 wt%) and two different filler sizes (13 nm and <50 nm), i.e., two different specific surface area values. During the research, specimen sets were cured gradually at increasingly higher temperatures (from 60 °C to 180 °C). Broadband dielectric spectroscopy (BDS) was used to determine the characteristics of the dielectric constant and the dielectric loss factor in the frequency range from 10−3 Hz to 105 Hz. As a result, it was possible to analyze the impact of the progressing polymer structure thermosetting processes on the observed dielectric parameters of the samples. The nano-Al2O3 addition with 0.5 wt%, 1.0 wt%, and 3.0 wt% resulted in a decrease in dielectric constant values compared to neat epoxy resin samples. The most significant reductions were recorded for samples filled with 0.5 wt% of 13 nm and <50 nm powders, by about 15% and 11%, respectively. For all tested samples, the curing process at a gradually higher temperature caused a slight decrease in the dielectric constant (approx. 2% to 9%) in the whole frequency range. Depending on the nanofiller content and the curing stage, the dielectric loss factor of the nanocomposite may be lower or higher than that of the neat resin. For all tested samples cured at 130 °C (and post-cured at 180 °C), the differences in the dielectric loss factor characteristics for frequencies greater than 100 Hz are low. For frequencies < 100 Hz, there are prominent differences in the characteristics related to the size of the nanoparticle and the individual wt% value. At a small nanofiller amount (0.5 wt%), a decrease in the dielectric constant and dielectric loss factor was observed for frequencies < 100 Hz for samples with nanofillers of both sizes.

Influence of the Graft Length on Nanocomposite Structure and Interfacial Dynamics.

Both the dispersion state of nanoparticles (NPs) within polymer nanocomposites (PNCs) and the dynamical state of the polymer altered by the presence of the NP/polymer interfaces have a strong impact on the macroscopic properties of PNCs. In particular, mechanical properties are strongly affected by percolation of hard phases, which may be NP networks, dynamically modified polymer regions, or combinations of both. In this article, the impact on dispersion and dynamics of surface modification of the NPs by short monomethoxysilanes with eight carbons in the alkyl part (C8) is studied. As a function of grafting density and particle content, polymer dynamics is followed by broadband dielectric spectroscopy and analyzed by an interfacial layer model, whereas the particle dispersion is investigated by small-angle X-ray scattering and analyzed by reverse Monte Carlo simulations. NP dispersions are found to be destabilized only at the highest grafting. The interfacial layer formalism allows the clear identification of the volume fraction of interfacial polymer, with its characteristic time. The strongest dynamical slow-down in the polymer is found for unmodified NPs, while grafting weakens this effect progressively. The combination of all three techniques enables a unique measurement of the true thickness of the interfacial layer, which is ca. 5 nm. Finally, the comparison between longer (C18) and shorter (C8) grafts provides unprecedented insight into the efficacy and tunability of surface modification. It is shown that C8-grafting allows for a more progressive tuning, which goes beyond a pure mass effect.

A facile and novel synthesis of bimetallic copper-manganese oxide nanoparticles anchored on carbon nanotubes

In the current contribution, copper-manganese bimetallic oxide nanoparticles attached to carbon nanotube surfaces have been created utilizing a straightforward method rather than complicated machinery. The employed sources of Cu and Mn were copper sulfate and potassium permanganate, which were combined with modified carbon nanotubes and thermally treated at 250, 350, and 450 °C, respectively. As the annealing temperature rises from 250 to 450 °C, the copper-manganese bimetallic oxide nanoparticles adhered to the surface of the carbon nanotubes gradually grow in size from 9 to 45 nm. XRD and FTIR methods were used to study structural characteristics. The existence of copper-manganese bimetallic oxide phases was established based on the results. The peak height and sharpness of the XRD data were also improved by increasing the annealing temperature, reflecting an improvement in the crystallinity. A broadband dielectric spectroscopy (BDS) was used to show how the applied frequency affected the dielectric characteristics.

High yield synthesis and study of Cu substitution on characteristics and dielectric properties of MgO nanostructures

High-permittivity materials are becoming more popular due to the electrical and electronic industrial development. Single composition materials are well known to fall short of high permittivity requirements. So, in this article, we report pure and Cu (5%, 7%, 9%, and 11%) doped MgO nanostructures synthesized by reverse micelle method and study of their dielectric properties. Energy Dispersive Analysis of X-rays (EDAX), Powder X-ray Diffraction (PXRD), diffused reflectance UV–Vis spectroscopy (DR-UV-Vis), Dynamic Light Scattering (DLS), photoluminescence (PL), Raman spectroscopy and Broadband Dielectric Spectroscopy (BDS) are among the characterization methods used. Each synthesized sample crystallizes in cubic crystal system. As Cu doping increases from 5% to 11%, the average crystallite size dwindles from 22 to 10 nm. The bandgap is reduced from 5.71 eV to 2.58 eV as per the optical results from DR-UV-VIS spectroscopy. The intensity and surface defects are correlated by PL spectra. Raman peak shifts to the higher angle side, which is related to XRD and associated with a reduction in average crystallite size. For pure and all doping concentrations, the dielectric constant and the dissipation factor decreases with the increment in frequency which is a peculiar behaviour of dielectric materials.

Rationalizing the interfacial layer in polymer nanocomposites: Correlation between enthalpy and dielectric relaxation

The accurate and convenient characterization of the interfacial layer is a crucial prerequisite for understanding the relationship between structure and macroscopic properties in polymer nanocomposites (PNCs). Herein, enthalpy relaxation and interfacial layer properties estimated from temperature-modulated differential scanning calorimetry (TMDSC) and broadband dielectric spectroscopy (BDS) of model PNCs with attractive interactions are investigated. We demonstrate that enthalpy relaxation enables the accurate quantification of the volume fraction of the interfacial layer (φint) as TMDSC and BDS. The parameter (χint) corresponding to the decreased degree of enthalpy hysteresis (ΔHR) related to the contribution of the interfacial layer, is identical with φint estimated from BDS, while presents only similar dependence on nanoparticle loading with φint estimated from TMDSC. This interesting phenomenon can be ascribed to the consistency between enthalpy and dielectric relaxation, which both characterize the dynamic change of polymer mainly originating from segmental relaxation. Such an unexpected correlation between enthalpy and dielectric relaxation provides a new approach to characterize the interfacial layer properties of PNCs and understand its impact on the glass transition behavior.

Effect of Diphenyl Content on Viscoelasticity of Poly(dimethyl-co-diphenyl)siloxane Melt and Network

Polydimethylsiloxane (PDMS) is one of the most widely used polymeric materials for sealants, adhesives, lubricants, and thermal as well as electrical insulation. At low temperatures, however, PDMS is subject to crystallization that can cause deterioration in mechanical function. A common way to suppress such crystallization is through the incorporation of phenylsiloxane into the backbone of polysiloxane. Nevertheless, the introduction of phenyl components, even in small quantities, could potentially change the properties of the siloxane in a significant way. In this work, a series of mechanical tests and finite element simulations were performed to study the macroscale viscoelasticity of two poly(dimethyl-co-diphenyl)siloxane formulations in order to understand the effects of a few percent diphenyl contents on the viscoelasticity of the polysiloxane material. We utilized the small-angle X-ray scattering to investigate the microscopic structures of the copolymers and broadband dielectric spectroscopy and rheology to probe the chain dynamics at the microscale. The results of these characterizations were used to inform the finite element simulations. We found that the degree of cross-linking does not significantly alter the microstructure but can profoundly affect the viscoelastic response of the copolymer networks. The corresponding hysteretic behavior is interpreted in terms of reptation-like motion and relaxation of the effective free chains in the cured polymer network. The relaxation of the copolymer chains is slowed significantly by even a small increase in the molar ratio of the diphenyl component.

The preparation and smart electrorheological behavior of MOF-Ti@PANI core-shell nanoparticles

In this paper, a kind of core–shell composite nanoparticles for electrorheological (ER) fluid was successfully prepared and showed good ER effect. The material possesses the high specific surface area and low density of metal organic frameworks (MOFs), and combines with the excellent dielectric properties of polyaniline (PANI). PANI precursors were prepared by a rapid mixing method, and then MOF-Ti (an MOF containing Ti) grew in situ on PANI under the solvothermal conditions. The MOF-Ti@PANI composite nanoparticles with core–shell structure were generated. These characteristics of PANI and MOF-Ti are conducive to stronger interfacial polarization of nanoparticles, which in turn leads to a good ER effect. The nanoparticle morphology as well as its ER and dielectric properties was modulated by using different amounts of PANI addition. The addition amount of PANI had a certain effect on the particle morphology, which was proved by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We also determined particle size at the nanoscale in this process. The measured results of the X-ray powder diffractometer (XRD) are consistent with the characteristic peaks of MIL-125 (a kind of MOF-Ti). The internal chemical structure of the material and the chemical environment of the elements were analyzed using Fourier infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Finally, the ER and dielectric properties of the nanoparticles in ER Fluids were investigated using high-speed rotational rheometry and broadband dielectric spectroscopy. The analysis revealed that the MOF-Ti@PANI core–shell nanoparticles have good ER properties under proper coating. For the core–shell modified MOFs, it is expected to be a promising development direction in the field of ER materials.

Hydration of the neurotransmitter [formula omitted]-aminobutyric acid and its isomer [formula omitted]-aminobutyric acid

Room-temperature aqueous solutions of the neurotransmitter γ-aminobutyric acid (GABA) and its isomer α-aminobutyric acid (AABA) were studied with broad-band dielectric relaxation spectroscopy (DRS) and statistical mechanics (1D-RISM and 3D-RISM) calculations. Comparison of the first-shell coordination numbers from 3D-RISM with the total effective hydration numbers from DRS revealed that for both solutes only about half of the H2O molecules in direct contact with the solute are affected in their dynamics. Whereas for GABA ∼10 of them are moderately retarded by a factor of ∼2–3 compared to bulk water and only ∼1–2 effectively frozen at vanishing solute concentration, AABA appears to be more strongly hydrated with only ∼6 moderately retarded but ∼6 H2O frozen by the solute molecule. This is reflected in the effective solute dipole moments.

Phase behaviour and relaxation dynamics of the asymmetric azoxybenzene

ABSTRACT The phase behaviour and molecular dynamics of the liquid crystal 4-decyl-4’-heptylazoxybenzene (abbreviated as 10AB7) are described by differential scanning calorimetry, polarized optical microscopy, X-ray diffraction and broadband dielectric spectroscopy. Upon fast cooling/heating rates, the 10AB7 forms two liquid crystal phases, nematic and smectic A, as well as two conformationally disordered crystal phases (one of them does not appear on cooling). Upon slow cooling, there is the multiplicity of crystal phases. The dielectric spectra reveal the complex dynamics in the individual thermodynamic states of 10AB7. The Arrhenius type high-frequency relaxation, related with the rotations around the long axes of molecules, is detected for each liquid-like phases and for the high-temperature crystal phase. In the crystal phases there is also the Arrhenius type relaxation associated with the collective motions of molecules combined due to the mutual interactions through NO molecular groups. Additionally, the Vogel–Fulcher–Tammann type process is visible in the low-temperature crystal phase.

Crystallization kinetics in the chiral compound showing the vitrification of the smectic CA* phase for moderate cooling rates

ABSTRACT The crystallization of the 3F5FPhF6 compound from the liquid crystalline antiferroelectric smectic CA* phase is investigated in various conditions using differential scanning calorimetry and polarizing optical microscopy. The kinetics of isothermal melt and cold crystallization is studied on the basis of the Avrami model. The kinetics of non-isothermal cold crystallization is analysed using the Ozawa model and the activation energy is determined by the Augis-Bennett, Friedman’s differential isoconversional and Matusita methods. The border temperature between the diffusion-controlled crystallization and thermodynamically-controlled crystallization is estimated. The high fragility index of 105 is determined from the α-process in the smectic CA* phase by the broadband dielectric spectroscopy. The metastable, conformationally disordered crystal phase, forming only via cold crystallization, is reported.

Polyanionic electrically conductive superabsorbent hydrogel based on sodium alginate-g-poly (AM-co-ECA-co-AMPS): Broadband dielectric spectroscopy investigations

In this study, the dielectric behavior of polyanionic electrically conductive superabsorbent hydrogel based on sodium alginate-g-poly(AM-co-ECA-co-AMPS) was investigated by broadband dielectric spectroscopy (BDS). The dielectric spectra obtained from −70 to 70 °C showed a superposition of three distinctive processes, electrode polarization, charge carrier's transport, and a molecular relaxation process. These dynamic processes were further analyzed along with the effect of both temperature and reduced graphene oxide (rGO) content. The development of a clear electrochemical double layer (ECDL) at the electrode/hydrogel interface strongly supports its possible application in supercapacitors' forms of energy storage. TGA, DSC, rheology, and electrochemical properties were studied. Furthermore, when the composite hydrogel with rGO content of 2.5 % was assembled into a symmetric supercapacitor, it displayed a specific capacitance of 756 F.g−1 at 1 A.g−1 and 704 F.g−1 after 5000 cycles with high capacitance retention of 93.2 %. The superior conductivity and porous structure of the rGO composite hydrogel are credited with the hydrogel's excellent electrochemical capabilities.

How Tuning Interfaces Impacts the Dynamics and Structure of Polymer Nanocomposites Simultaneously

Fundamental understanding of the macroscopic properties of polymer nanocomposites (PNCs) remains difficult due to the complex interplay of microscopic dynamics and structure, namely interfacial layer relaxations and three-dimensional nanoparticle (NP) arrangements. The effect of surface modification by alkyl methoxysilanes at different grafting densities has been studied in PNCs made of poly(2-vinylpyridine) and spherical 20 nm silica NPs. The segmental dynamics has been probed by broadband dielectric spectroscopy and the filler structure by small-angle X-ray scattering and reverse Monte Carlo simulations. By combining the particle configurations with the interfacial layer properties, it is shown how surface modification tunes the attractive polymer-particle interactions: bare NPs slow down the polymer interfacial layer dynamics over a thickness of ca. 5 nm, while grafting screens these interactions. Our analysis of interparticle spacings and segmental dynamics provides unprecedented insights into the effect of surface modification on the main characteristics of PNCs: particle interactions and polymer interfacial layers.

Dielectric Characterization of Core-Shell Structured Poly(vinylidene fluoride)-grafted-BaTiO3 Nanocomposites.

Dielectric properties of poly(vinylidene fluoride)-grafted-BaTiO3 (PVDF-g-BT) core-shell structured nanocomposites obtained from Reversible Addition Fragmentation chain Transfer (RAFT) polymerization of VDF were investigated by Broadband Dielectric Spectroscopy (BDS). The dielectric constant increased along with the BT content, about +50% by addition of 15 vol% of BT, which was around 40% more than expected from predictions using the usual dielectric modeling methods for composite materials, to be ascribed to the effect of the interfacial core-shell structure. The known dielectric relaxations for PVDF were observed for the neat polymer as well as for its nanocomposites, not affected by the presence of nanoparticles. A relaxation process at higher temperatures was found, due to interfacial polarization at the amorphous-crystalline interface, due to the high crystallinity of materials produced by RAFT. Isochronal BDS spectra were exploited to detect the primary relaxation of the amorphous fraction. Thermal analysis demonstrated a very broad endotherm at temperatures much lower than the usual melting peaks, possibly due to the ungrafted fraction of the polymer that is more easily removable by repeated washing of the pristine material with acetone.

Inter and intra molecular dynamics in poly(trimethylene 2,5-furanoate) as revealed by infrared and Broadband Dielectric Spectroscopies

Infrared spectroscopy (IR) and Broadband Dielectric Spectroscopy (BDS) experiments have been performed in poly(trimethylene 2,5-furanoate)(PTF) and poly(trimethylene terephthalate)(PTT) below their glass transition temperatures. The BDS experiments reveal a richer inter-molecular dynamic for PTT as characterized by a multimodal β relaxation in contrast with the monomodal one exhibited by PTF. The evolution with temperature of comparable IR absorption bands is very similar for PTF and PTT and shows small shifts in wavenumbers towards lower values, with exception of the band related to the stretching mode of the carbonyl group. In addition, a significant difference appears in the shape of the bands associated with the –CO stretching. While for PTT the absorption feature is comprised of a single component, that for PTF exhibits several components suggesting the presence of hydrogen bonds. This effect may be responsible for the monomodal shape of the β relaxation of PTF since a higher degree of intramolecular coupling between the furan ring and the rest of the monomer is expected. Density Functional Theory (DFT) calculations support the experimental results revealing that as temperature increases an increment of the syn conformations of the 2,5-furandicarboxylic acid (FDCA) moiety is likely to occur in the amorphous state. The energy gain from more stable anti to less stable syn isomers can be compensated by the formation of hydrogen bonds between interchain FDCA moieties in syn conformations. This effect may cause additional hindrance to the intermolecular dynamics of the dielectric β relaxation. It is conceivable that the hindrance exhibited by PTF in both intra and inter-molecular dynamics may play a role in the reduction of gas diffusion and permeability of PTF in comparison with PTT.

Magnetic and Electrical Characteristics of Nd3+-Doped Lead Molybdato-Tungstate Single Crystals.

Single crystals of Pb1-3x▯xNd2x(MoO4)1-3x(WO4)3x (PNMWO) with scheelite-type structure, where ▯ denotes cationic vacancies, have been successfully grown by the Czochralski method in air and under 1 MPa. This paper presents the results of structural, optical, magnetic and electrical, as well as the broadband dielectric spectroscopy measurements of PNMWO single crystals. Research has shown that replacing diamagnetic Pb2+ ions with paramagnetic Nd3+ ones, with a content not exceeding 0.01 and possessing a screened 4f-shell, revealed a significant effect of orbital diamagnetism and Van Vleck's paramagnetism, n-type electrical conductivity with an activation energy of 0.7 eV in the intrinsic area, a strong increase of the power factor above room temperature for a crystal with x = 0.005, constant dielectric value (~30) and loss tangent (~0.01) up to room temperature. The Fermi energy (~0.04 eV) and the Fermi temperature (~500 K) determined from the diffusion component of thermopower showed shallow donor levels.

Preparation of lead hexaferrite filled PVA- PVP nanocomposite and a study of its structural features, optical and dielectric properties

Polymer blend films based on PVA-PVP filled with PbFe12O19 hexa-ferrites nanoparticles were created by solution casting technique. XRD, HRTEM, FESEM, FTIR, UV–vis spectroscopy and Broad-band dielectric spectroscopy were used to examine the properties of the prepared polymer composite films. X-ray diffraction pattern of the powder confirmed the formation of PbFe12O19 with hexagonal phase and that for the films confirmed the incorporation of the PbFe12O19 nanoparticles in the PVA-PVP blends. HRTEM confirms the formation of hexagonal nanoparticles with average size ranged from 7 nm to 21 nm. Field emission scanning electron microscopy (FESEM) studied the morphology of the nanocomposite films. There are noticeable variations in FT-IR spectra that confirm the incorporation of PbFe12O19, NPs in PVA-PVP blend. The absorbance was found to increase with red shift in the ultraviolet-visible region while the transmittance decreases with increasing PbFe12O19, nanoparticles. By incorporating, PbFe12O19 the direct optical gap and indirect optical gap gradually decreased from 5.20 eV to 4.44 eV and 4.97 eV to 4.34 eV, respectively while the Urbach energy increases from 0.274 eV to 0.678 eV. According to the Wemple-Didomenico single oscillator model, the optical dispersion parameters have been examined and are found to be strongly affected by PbFe12O19, loading. Additionally, the nanocomposite film containing 7.5% PbFe12O19, demonstrated outstanding optical shielding. The complex dielectric constant (ε*), complex electric modulus (M*) and electrical conductivity, of NCPs materials have been studied with the frequency changing from 0.1 Hz to 10 MHz. The real permittivity () of PVA-PVP blend polymer film increased while the real electric modulus (M′) is found to decrease by the incorporation of PbFe12O19, nanoparticles up to 2.5 wt.% and the imaginary component of permittivity follows the same pattern of The examined nanocomposite films show promise for flexible optoelectronics, photosensors, optical shielding and nano-dielectric materials.