High Performance of Titanium Dioxide Reinforced Acrylonitrile Butadiene Rubber Composites

Recently, dielectric elastomer actuators (DEA) have emerged as one of the most promising materials for use in soft robots. However, DEA needs a high operating voltage and high mechanical properties. By increasing the dielectric constant of elastomeric materials, it is possible to decrease the operating voltage required. Thus, elastomeric composites with a high dielectric constant and strong mechanical properties are of interest. The aim of this research was to investigate the effect of titanium dioxide (TiO₂) content ranging from 0 to 110 phr on the cure characteristics, and physical, dielectric, dynamic mechanical, and morphological properties of acrylonitrile butadiene rubber (NBR) composites. The addition of TiO₂ reduced the scorch time (t_s1) as well as the optimum cure time (t_c90) but increased the cure rate index (CRI), minimum torque (M_L), maximum torque (M_H), and delta torque (M_H - M_L). The optimal TiO₂ content for maximum tensile strength and elongation at break was 90 phr. Tensile strength and elongation at break were increased by 144.8% and 40.1%, respectively, over pure NBR. A significant mechanical property improvement was observed for TiO₂-filled composites due to the good dispersion of TiO₂ in the NBR matrix, which was confirmed by scanning electron microscopy (SEM). Moreover, incorporating TiO₂ filler gave a higher storage modulus, a shift in glass transition temperature (T_g) to a higher temperature, and reduced damping in dynamic mechanical thermal analysis (DMTA). The addition of TiO₂ to NBR rubber increased the dielectric constant of the resultant composites in the tested frequency range from 10² to 10⁵ Hz. As a result, TiO₂-filled NBR composite has a high potential for dielectric elastomer actuator applications.

Electrical properties of amorphous Ge26InxSe74-x chalcogenide thin films

Amorphous Ge26InxSe74-x (1 ≤ × ≤ 5) chalcogenide thin films have been deposited by thermal evaporation technique. The temperature-dependence of DC conductivity and the temperature and frequency dependence of AC conductivity have been studied in the temperature range 295–523 K and in the frequency range 4–8 MHz. The study of the temperature-dependent of DC conductivity refers to the presence of two distinct conduction mechanisms; the activation energies for each were calculated and it was observed that their values decrease by increasing In content. Besides, in the low-temperature region, the variation of the conductivity against temperature was further analyzed according to the variable-range hopping model based on Mott’s relation, whereby the hopping parameters were evaluated. For all investigated compositions, the variation of the AC conductivity against frequency at the studied temperatures was interpreted according to the correlated barrier hopping (CBH) model which based on Jonscher’s power law, whereby the potential barrier height, WM, and the theoretical optical bandgap, Eg, were calculated.

Outstanding Electrode-Dependent Seebeck Coefficients in Ionic Hydrogels for Thermally Chargeable Supercapacitor near Room Temperature

Thermoelectric power generation from waste heat is an important component of future sustainable development. Ion-conducting materials are promising candidates because of their high Seebeck coefficients. This study demonstrates that ionic hydrogels based on imidazolium chloride salts exhibit outstanding Seebeck coefficients of up to 10 mV K^-1. Along with their relatively high ionic conductivities (1.6 mS cm^-1) and extremely low thermal conductivities (∼0.2 W m^-1 K^-1), these hydrogels have good potential for use in heat recovery systems. The voltage behavior in response to temperature difference (stable or transient) differs significantly depending on the metal electrode material. We evaluated the electrode-dependent temperature sensitivity of the double layer capacitance of these hydrogels, which revealed that the thermally induced polarization of ions at the interface is one of the main contributors to the thermovoltage. Our results demonstrate the potential capability for ion and metal interactions to be used as an effective baseline for exploring ionic thermoelectric materials and devices. The developed thermoelectric supercapacitor exhibits reversible charging-discharging behavior under repeated disconnecting-connecting of an external load with a constant temperature difference, which offers a novel strategy for heat-to-electricity energy conversion from steady-temperature heat sources.

Stabilization of cyclic water tetramers and dimers in the crystal host of 2D coordination networks: electrical conductivity and dielectric studies

Construction of Zn(ii)-based 2D coordination polymers for selective recognition of water tetramers and dimers in crystal hosts and their exploitation in electrical studies.

Polyaniline-Grafted RuO2-TiO2 Heterostructure for the Catalysed Degradation of Methyl Orange in Darkness

Massive industrial and agricultural developments have led to adverse effects of environmental pollution resisting conventional treatment processes. The issue can be addressed via heterogeneous photocatalysis as witnessed recently. Herein, we have developed novel metal/semi-conductor/polymer nanocomposite for the catalyzed degradation and mineralization of model organic dye pollutants in darkness. RuO2-TiO2 mixed oxide nanoparticles (NPs) were modified with diphenyl amino (DPA) groups from the 4-diphenylamine diazonium salt precursor. The latter was reduced with ascorbic acid to provide radicals that modified the NPs and further served for in situ synthesis of polyaniline (PANI) that resulted in RuO2/TiO2-DPA-PANI nanocomposite catalyst. Excellent adhesion of PANI to RuO2/TiO2-DPA was noted but not in the case of the bare mixed oxide. This stresses the central role of diazonium compounds to tether PANI to the underlying mixed oxide. RuO2-TiO2/DPA/PANI nanocomposite revealed superior catalytic properties in the degradation of Methyl Orange (MO) compared to RuO2-TiO2/PANI and RuO2-TiO2. Interestingly, it is active even in the darkness due to high PANI mass loading. In addition, PANI constitutes a protective layer of RuO2-TiO2 NPs that permitted us to reuse the RuO2-TiO2/DPA/PANI nanocomposite nine times, whereas RuO2-TiO2/PANI and RuO2-TiO2 were reused seven and five times only, respectively. The electronic displacements at the interface of the heterojunction metal/semi-conductor under visible light and the synergistic effects between PANI and RuO2 result in the separation of electron-hole pairs and a reduction of its recombination rate as well as a significant catalytic activity of RuO2-TiO2/DPA/PANI under simulated sunlight and in the dark, respectively.

Observation of self-polarization in BSA protected Au20 clusters

Bovine serum albumin (BSA)-protected gold clusters (atomicity ∼ 20), prepared using a wet chemical route, show strong dipolar radiative transition with a gap energy of 1.93 eV due to the high oscillator strength, as confirmed by the emission studies. Self-arrangement of the clusters with fixed atomicity yields a low dispersive dielectric and electric self-polarization nature. The electrical hysteresis loop measurements returned a remanent polarization of 0.05 μC cm^-2, which can be correlated with the dipolar orientation (activation energy ∼ 45.32 meV), originating from the structure-dependent deformation of the charge density.

Efficiently synthesized Co doped Cu3TeO6 accounted for its anomalous behaviour in electronic properties

Efficient synthesis of Cu_3−xCo_xTeO₆ (x = 0.0, 0.1, 0.3 or 0.5) yields cubic morphologies, which exhibit remarkable electronic and enhanced permittivity properties.