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Composite material based on polyethylene glycol (PEG) and polypyrrole (PPy) polyrotaxanes both encapsulated into α‐cyclodextrins (α‐CDs) macrocycle molecules was synthesized by cross‐linking reaction. The effect of PPy‐αCD polyrotaxane incorporation into the PEG‐αCD polyrotaxane matrix, on the structural, morphological, thermal, and dielectric properties was evaluated and compared to the reference material. Scanning electron microscopy spectroscopy indicates different surface morphologies of this material in comparison to the reference one. In addition, the contact angle measurements and surface free energy attest a hydrophilic surface, while the reference material exhibits a hydrophobic surface. More than that, the presence of the PPy‐αCD cross‐linked into the matrix has a beneficial effect on the thermal properties. The composite material shows an enhanced dielectric constant value of 31,365 at 10 Hz frequency compared to the 38.2 of the reference material, and higher dielectric loss (62,398 vs. 80 at 10 Hz, respectively). The conductivity measurements at 10 Hz frequency indicated for the reference material the value 4.5 × 10−11, while for the material with PPy‐αCD polyrotaxane, the conductivity is three orders of magnitude higher (3.5 × 10−8) confirming the improvements of the electrical properties.

By using broadband dielectric spectroscopy over a wide frequency and temperature range, the effect of the chain extender and cross‐linkers on molecular dynamics of polyurethanes based on piperazine as a heterocyclic compound was assessed. Three relaxations attributed to local motions of polar side groups and small segments of the polyurethane chain (β, γ‐mode) and glass transition (α‐mode) were detected with the increase in temperature from −120 to 100 °C, along with the conductivity process at high temperatures and low frequencies. Experimental data were examined using the impedance and electric modulus for the conductivity study. Due to the presence of dipole polarization of functional groups in the hard segments, cross‐linked polyurethanes are characterized by higher dielectric constant value (≈11 at 1 kHz and 25 °C) compared to the linear ones (≈6–7 at 1 kHz and 25 °C). High conductivity was achieved for the Tween 20‐cross‐linked polyurethanes. The activation energy for the secondary γ relaxation was in the range of 34–37 kJ mol−1for all polyurethanes, regardless of the chain extender or cross‐linker used. Piperazine‐based polyurethanes had lower activation energies for α relaxation and high conductivity compared to cyclohexane‐based polyurethanes. This indicates that α relaxation is more vulnerable to structural alterations.

• Flexible and tough films are prepared from OH-modified poly(ether-imide)s (PEIs) • The PEI films withstand high temperature, with no mass loss up to 400 °C • The dielectric character of PEI films is maintained in a large temperature range • The PEI films display high chemical resistance against MEK and alkaline solutions • A graphite paint-coated film functions as working electrode in cyclic voltammetry A series of films prepared from poly(ether-imide)s (PEI) containing a hydroxyl group and various flexible bridges has been investigated to survey the applicative potential. The structure-property correlations were studied to explore the influence of the structural design on the overall physico-chemical properties. FTIR spectra confirmed the complete imidization of polyamidic acid precursors used for films preparation. These films exhibited high glass transition temperatures, and two stages of decomposition, being thermally stable up to 400 °C, with a char residue up to 68.97 %. A systematic non-isothermal kinetic study was accomplished to evaluate the kinetic parameters of the thermogravimetric curves. The dielectric behaviour of the PEI films was assessed on the bases of dielectric constant, dielectric loss, secondary relaxations, dielectric loss processing by Havriliak-Negami model and conductivity studies. Beside the mechanical behaviour evaluation, these polymer films were subjected to chemical resistance tests in the presence of methyl ethyl ketone and an alkaline solution. To prove their suitability for use as flexible electrodes, e.g. electrochemical storage devices, the films were coated with a graphite-containing paint and analysed in comparison with indium tin oxide-coated glass with respect to the electrical response in a standard electrochemical cell. [ABSTRACT FROM AUTHOR]

Understanding the intricate relationship between conductivity and polymer film microstructure is paramount to designing and developing high-performance conjugated-polymer-based electronic devices. Conjugated polymers are typically semicrystalline, and their films comprise both highly crystalline and amorphous regions with significant disparity between the conductivity of these regions. However, traditional conductivity measurements under steady-state conditions overlook the presence of the amorphous phase, offering an incomplete perspective on charge transport. Here, by employing isothermal dielectric measurements, we reveal that the amorphous phase plays a pivotal role and dominates the electrical conductivity at temperatures more pertinent to practical applications, while the crystalline fraction takes precedence at temperatures below room temperature. The conductivity mismatch between the amorphous and crystalline phases yields the Maxwell-Wagner-Sillars interfacial polarization (MWS-IP) effect. Here we demonstrated that the existence of MWS-IP ensues a universal scaling between the electrical conductivity, the relaxation time and the dielectric relaxation strength, for various conjugated polymers and their blends. Shedding light on the contribution of the amorphous phase in the conductivity of conjugated polymers can lead to the development of new polymers for applications in electronic devices with improved performance at operationally relevant temperatures.

To combat the issue of plastics contamination of the medium, the current technologies are aiming towards development of green materials that are substituting the harmful elements from the disposed devices. This article opens a fresh perspective on designing novel polymer composites by loading hydroxypropyl methylcellulose (HPMC) with bio-derived filler or a mixture of bio-filler and barium titanate (BT) to make alternative eco-compatible materials for energy storage. New insights are extracted from a detailed analysis that correlates the solution behavior to solid state analysis. Rheological data evidence that for attaining uniform dielectric layers spinning times beyond 100 s and spinning speeds below 80 rpm are required. Interfacial compatibility with metal electrodes is checked via experiments of sample wetting on silver or gold layer, showing that adhesion work is increased of 6.24 times for gold support and 5.63 times for silver support, being adequate for capacitor applications. The sample morphology was recorded by scanning electron microscopy, indicating good dispersion of the filler or filler mixture in the bulk cellulose derivative matrix. Refractometry experiments revealed an enhancement of molecular polarizability upon loading, which led to increase of refractive index from 1.52 for neat HPMC to 1.56 for HPMC/oat 40 and 1.57 for HPMC/oat + BT 40, at 489 nm. This is reflected in the increase of the dielectric constant at 1 KHz, namely: 2.19 (HPMC) to 2.79 (HPMC/oat 40) and 3.36 (HPMC/oat + BT 40). The dielectric breakdown is slightly lowered upon loading from 43.8 ∙106 V/m (matrix) to 42.3∙106 V/m (HPMC/oat 40) and 42.0∙106 V/m (HPMC/oat + BT 40). The resulted electric energy density values reach at highest loading the values of 2.198∙104 J/m3for the sample with oat and 2.635∙104 J/m3for the sample with oat and BT. This work is a fresh initiative of making eco-compatible dielectrics for future storage systems.

The article reports the obtaining and characterization of high-performance nanocomposite materials based on modified polysulfone using various amounts of modified carbon nanotube fillers, namely 0.5 wt%, 1 wt%, 2.5 wt%, and 5 wt%. The structures of these systems were simulated and some physico-chemical parameters were estimated, showing the influence of the material composition. The solution casting process was involved for the composite systems preparation. The filler amount affected the structure of the nanocomposites impacting their properties. Raman spectroscopy analysis indicated certain chemical changes in the nanocomposite structures. Thermal characterization showed that nanocomposite's glass transition temperature domain increase with nanofiller content. Mechanical testing indicated an enhancement of the Young's modulus after reinforcing the polymer. Atomic force microscopy stated the presence of the filler in the polymer matrix, the density of the surface features being higher as filler concentration increased. The force curve spectroscopy supported an intensification of the adhesion force measured between the sample and the tip of the cantilever with the increase of the amount of the filler in the nanocomposite, completing the mechanical tests at nanoscale. The electrical permittivity and conductivity of the nanocomposites were investigated by Broadband dielectric spectroscopy at variable electric field frequency. The results revealed a significant enhancement of the electrical conductivity of the studied composite materials, especially at high filler loadings.