Semiconducting Region Research Articles

Probing effect of counterions on electric field stimuli responsive behaviours of smart organoboron-based polyelectrolytes

This is the first study to be introduced to the electrorheology (ER) literature focusing on organoboron-based polyelectrolyte colloidal systems namely: polymeric lithium tartaric acid borate (Poly-LiTB) and polymeric sodium tartaric acid borate (Poly-NaTB). Syntheses of functional polyelectrolytes were monitored via 1H-NMR, ATR-FTIR and SEM-EDX analyses. Electrical conductivity measurements indicated that Poly-LiTB and Poly-NaTB were in semi-conductive region indicating potential smart ER behaviour. A higher polarizability was detected for 20 wt.% Poly-LiTB dispersions in silicone oil (SO) by dielectric measurements. As expected, improved ER performances were obtained for Poly-LiTB/SO colloidal dispersion (τy = 265 Pa, EReff = 87, G′ = 80 kPa at 10 Hz, τc = 98 Pa, recovery% = 68) compared to Poly-NaTB/SO colloidal dispersion (τy = 195 Pa, EReff = 38, G′ = 42 kPa at 10 Hz, τc = 42 Pa, recovery% = 67). To sum up, it was determined that the best ER activity was detected by the organoboron-based polyelectrolyte containing Li+ counterion with smaller ionic radius and higher ionic mobility when their physicochemical properties are taken into account.

NUV-excitation Dy(III) complexes: Synthesis, structural study and impact of secondary ligands on optoelectronic properties

The ternary dysprosium complexes involving 1,1,1-trifluoro 5,5-dimethyl 2,4-hexanedione (TFDH) along with 2,2ʹ-bipyridyl and its derivatives have been synthesized. Elemental, infrared and proton NMR analyses were used to evaluate the bonding patterns between dysprosium ion and organic moieties. UV–Visible and photoluminescence spectroscopy were used to examine the optical characteristics. To confirm the anhydrous nature of synthesized complexes, IR and thermogravimetric data were utilized. The band gap value lies in semi-conducting region was explained by Tauc's plot and CV curve, respectively. The photophysical characteristics of dysprosium complexes have been studied in powdered form. The appearance of yellow luminescence on irradiation under NUV-light indicates a highly efficient transfer of energy mechanism from organic ligand to the Dy(III) ion. The CCT values were found to be suitable for cold light sources. The ∆J = 2 transition dominates the overall emission spectra with branching ratio ∼70% is ideal for laser reinforcement. The synthesized Dy(III) complexes possess band gap in semi-conducting range, good thermal stability and high luminous properties, which makes them suitable for applications in displays and lighting technologies.

Phase-engineering the Andreev band structure of a three-terminal Josephson junction

In hybrid Josephson junctions with three or more superconducting terminals coupled to a semiconducting region, Andreev bound states may form unconventional energy band structures, or Andreev matter, which are engineered by controlling superconducting phase differences. Here we report tunnelling spectroscopy measurements of three-terminal Josephson junctions realised in an InAs/Al heterostructure. The three terminals are connected to form two loops, enabling independent control over two phase differences and access to a synthetic Andreev band structure in the two-dimensional phase space. Our results demonstrate a phase-controlled Andreev molecule, originating from two discrete Andreev levels that spatially overlap and hybridise. Signatures of hybridisation are observed in the form of avoided crossings in the spectrum and band structure anisotropies in the phase space, all explained by a numerical model. Future extensions of this work could focus on addressing spin-resolved energy levels, ground state fermion parity transitions and Weyl bands in multiterminal geometries.

A joint investigation of Saturn’s deep zonal flow via its gravitational field and Ohmic dissipation

ABSTRACT The Cassini Grand Finale provided a unique opportunity to study Saturn’s deep zonal flow. In this paper, we present a comprehensive deep zonal flow model for Saturn using a joint inversion of observed gravity and zonal flow-induced Ohmic dissipation in the semi-conducting region, under the assumption that the planet’s cloud-level wind is limited to a shallow weather layer. Our model unveils a strong equatorially symmetric zonal flow (O(100) m s−1) and a weaker antisymmetric zonal flow (O(1) m s−1) beneath the cloud-level winds. Furthermore, we show that the maximum depth of the deep zonal flow is around 7800 km, surpassing previous results derived from gravity alone and with the assumption that the rapid cloud-level winds extend deep into the planet’s interior. The meridional profile of the deep zonal flow differs significantly from the cloud-level zonal winds and predicts a strong westward zonal flow in the region with latitude around ±23°, where the observed cloud-top winds remain eastward. We also demonstrate that the zonal flow inside and outside the tangent cylinder exhibits significant differences in speed and scale. Moreover, our findings suggest that the coupling between the deep zonal flow and cloud-level winds varies across latitudes, with the shallow-wind model applicable to polar regions within the tangent cylinder and the deep-wind model more relevant to equatorial regions outside the tangent cylinder. Our findings highlight the importance of accounting for the planet’s deep zonal flow in future studies of Saturn’s atmospheric dynamics.

Selective Purity Modulation of Semiconducting Single-Walled Carbon Nanotube Networks for High-Performance Thin-Film Transistors

Single-walled carbon nanotube (SWCNT) random networks have become strong candidates for next-generation electronics due to their exceptional mechanical, electrical, and optical properties. However, metallic nanotubes in networks generally incur a trade-off between the charge carrier mobility and on/off ratio, limiting the performance of SWCNT-based devices. Therefore, various methods to increase the purity of semiconducting nanotubes in entire random networks have been reported, but this direction has faced other issues, such as nanotube shortening, higher cost, and higher energy. Here, we introduce SWCNT random network-based thin-film transistors (SWCNT TFTs) with a varying purity profile of semiconducting SWCNTs across the channel, exploiting the superior mobility of metallic SWCNTs by partially tuning the semiconducting SWCNT purity and developing a novel perspective on metallic nanotubes in semiconductor channels. Based on the high-precision drop-on-demand capability of inkjet printing and various concentrations of semiconducting SWCNT ink, we form selectively patterned channel regions with different semiconducting SWCNT purities. The metallic nanotube-dominant region drastically increases the carrier density with a minimized Schottky barrier, while high-purity semiconducting regions at the channel boundaries effectively block off-state leakage through carrier depletion. As a result, the SWCNT TFTs with selectively patterned metallic nanotube regions show superior carrier mobility (75.50 cm2 V–1 s–1) and channel width normalized on-current (34.33 nA μm–1) without compromising the on/off ratio (1.62 × 107). To show the feasibility of our device in high-performance electronics, we demonstrate all-inkjet-printed flexible display driving circuits with two transistors that enable low-power, high-performance operation in display applications.

Computational analysis of geometric structures and edge‐termination effects of boron‐nitride and edge‐termination boron‐nitride nanoribbons

AbstractIn this work, we examined geometry, electronic structure, and edged termination effect of boron‐nitride nanoribbons (BNNRs) by employing localized Gaussian‐type orbital, periodic‐boundary condition, density functional theory (LGTO‐PBC‐DFT) calculations. Armchair (ABNNR) and zigzag (ZBNNR)‐type BNNRs are obtained and then bond lengths variation in two types of BNNRs are analyzed. We find that the B‐N bond length variation of ZBNNR is less diverse than that of ABNNR, and decreases with an increase in the ribbon width, monotonically. For those in ABNNR, it appears as an oscillatory convergence as a function of the ribbon width. The energy gap of edged termination ABNNR and ZBNNRs are also calculated using OH and SH as electron donating groups and CN‐, and Cl‐ as electron‐withdrawing groups. The introduction of SH‐ and Cl‐terminator significantly reduce the energy gap to the semiconducting region for ZBNNR, but for ABNNR. These calculated results may be exploited for nano‐electronic applications. To examine the surface behavior of the BNNRs, we also calculated their Raman shifts with the edge termination effects.

Intrinsic spin-valley locking for conducting electrons in metal-semiconductor-metal lateral heterostructures of 1H -transition-metal dichalcogenides

Lateral heterostructures of atomic layered materials alter the electronic properties of pristine crystals and provide a possibility to produce useful monolayer materials. We reveal that metal-semiconductor-metal lateral heterojunctions of $1H$-transition-metal dichalcogenides intrinsically possess conducting channels of electrons with spin-valley locking without any extrinsic fabrication breaking the crystal symmetry, e.g., gate electrodes. We theoretically investigate the electronic structure and transport properties of lateral heterojunctions and show that the heterostructure produces conducting channels through the $K$ and ${K}^{\ensuremath{'}}$ valleys in the semiconducting transition-metal dichalcogenides and restricts the spin of the conducting electrons in each valley due to the valley-dependent charge transfer effect. Moreover, the theoretical investigation shows that the heterojunction of ${\mathrm{WSe}}_{2}$ realizes a high transmission probability for valley-spin locked electrons even in a long semiconducting region. The heterojunction also provides a useful electronic transport property, a steplike I-V characteristic.

Contact Effect On Twisted Graphene Based Schottky Transistor

Owing to the exceptional electrical properties of different one dimensional (1D) classifications of graphene structure such as graphene nanoribbon (GNR) and twisted graphene (TWG) led to a revolution in nanoelectronic researche and applications. Thus, these materials have been extensively explored in nanoelectronics science and materials. This paper is focused on GNR and TWG junction as metal-semiconductor-metal (MSM) in the form of a transistor. The wave vectors of TWG and GNR based on the geometrical effects are discussed. By considering 1D potential barrier at the junction of TWG as a semiconducting region and GNR as a metallic region, the transmission probability is calculated. Then, the I–V characteristics of GNR-TWG Schottky transistor based on quantum tunneling effect arepresented and discussed, as well. The performance of GNR-TWG Schottky transistor under variation of gate-source voltage, channel length, number of twists, width of GNR, and temperature are investigated. It is concluded that increment in number of twists and width of GNR lead to increasing the drain current and threshold voltage. Finally, comparison study with graphene nanoscroll (GNS) Schottky transistor, trilayer graphene nanoribbon (TGNR) Schottky transistor, and reported experimental data are performed and results represent that GNR-TWG Schottky transistor has larger drain current than these works.

High dielectric permittivity and dielectric relaxation behavior in a Y2/3Cu3Ti4O12 ceramic prepared by a modified Sol−Gel route

In this work, Y2/3Cu3Ti4O12 ceramics were fabricated via a modified sol−gel route. Structural, dielectric, and electrical parameters were systematically investigated. The XRD results indicate that a CaCu3Ti4O12 phase (JCPDS No. 75–2188) is present in every sintered sample. SEM images of Y2/3Cu3Ti4O12 ceramics disclose a fine-grained ceramic microstructure. Interestingly, high dielectric permittivity, ∼6600–7600, with loss tangents of ∼0.918–1.086 were achieved in the sintered Y2/3Cu3Ti4O12 samples. Density functional theory (DFT) calculations were used to investigate the most stable structure of the Y2/3Cu3Ti4O12 ceramics. Our DFT results reveal that two calcium vacancies (VCa) are isolated from each other. We also determined the lowest energy configuration of an oxygen vacancy (VO) in the Y2/3Cu3Ti4O12 ceramics occurred during the sintering process. We found that the VO is trapped close to the Y atom in this structure. Both computational and experimental studies specify that the oxygen vacancy is located close to the Y atom in the Y2/3Cu3Ti4O12 lattice and it might be a bivalent oxygen vacancy. As a result, due to charge balance, charge compensation of the transition ions, i.e., Cu and Ti ions, might take place. The charge compensation mechanisms in the Y2/3Cu3Ti4O12 lattice were verified using an XPS technique. Impedance spectroscopy confirms the presence of an inhomogeneous microstructure consisting of semiconducting grains and insulating grain boundaries in the sintered Y2/3Cu3Ti4O12 ceramics. This electrical result is consistent with the computational analysis, showing that a charge compensation mechanism might be involved in generation of the grains' semiconductive region due to the presence of a VO. Consequently, high dielectric permittivity in Y2/3Cu3Ti4O12 may have originated from an internal barrier layer capacitor (IBLC) effect.

Embedding nanostructure and colossal permittivity of TiO2-covered CCTO perovskite materials by a hydrothermal route

In this article, hydrothermal methods were employed to synthesize CaCu3Ti4O12-based powders with a surface coverage of nano-sized TiO2 particles in molar ratio Ti4+/CCTO of 0, 0.1, 0.2, and 0.3. The phase structure, morphology, and compositional distribution of TiO2-covered CCTO powders were systematically characterized. Using the synthesized powders as starting materials, dense ceramics with very giant dielectric constants at room temperature (εr>7.0 ×105 at 20 Hz and εr>4.0 ×105 at 1 kHz) were successfully fabricated by sintering at 1050 °C for 8 h. Meanwhile, the embedding nanocrystalline structures were observed in grain interiors of TiO2-covered CCTO ceramics. The investigation of dielectric properties and impedance spectra confirm that, except the double-Schottky barriers on the grain boundaries, there is a low resistivity region in TiO2/CCTO composite ceramics, originated from the inhomogeneous nano-scale semiconducting regions, which formed by the dispersion of Ti4+ ions to replace Cu2+ positions in the grain interiors. According to the results, a model of nanocrystalline interface barrier layer capacitors is proposed to reasonably explain the colossal permittivity behaviors of nano-size TiO2-covered CCTO perovskite materials.

Structural, magneto transport and magnetic properties of Ruddlesden–Popper La2-2xSr1+2xMn2O7 (0.42≤x≤0.52) layered manganites

The magneto transport of Ruddlesden–Popper, La2-2xSr1+2xMn2O7 (0.42≤x≤0.52), 2-dimensional bilayered manganites have been investigated in a broad temperature range. The samples have been synthesized using the solid-state reaction method. Rietveld refinement of the X-ray diffraction data indicates the tetragonal structure formation with I4/mmm space group. The resistivity curves of the samples present a general characteristic of metal-insulator (MI) transition at certain temperature (TMI). Besides, for samples with x = 0.48, 0.50, and 0.52, at a certain temperature (TCO) well below TMI the charge ordering is also evident. Furthermore, the samples display a shallow upturn in resistivity below Tmin due to the Kondo like spin scattering effect, weak localization and electron-phonon interaction. The high temperature semiconducting (T>TMI) region, the resistivity curve follows the 3D Mott’s variable hopping transport mechanism. The overall suppression of resistivity accounts for a substantial magnetoresistance by applying a magnetic field and the characteristic change in TMI, TCO, and Tmin are discussed. Temperature-dependent magnetization demonstrates the suppression of ferromagnetism and evident of antiferromagnetic nature with an apparent charge ordering with increasing concentration of Sr2+.

Phase structure and electrical and mechanical properties of PLLA/ionic conductive polyether blends prepared by melt mixing

Poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) is known as an ionic conductive polymer and exhibits ionic conductivity when it forms a complex with a metal salt. In this study, poly(L-lactic acid) (PLLA)/POEGMA/poly(methyl methacrylate) (PMMA) blends were manufactured to develop high-performance polymer materials that exhibit high mechanical moduli (>1 GPa) and ionic conductivities in the semiconductive region (1.0 × 10 −9–1.0 × 10−7 cm−1) at room temperature. In addition, crystallized blends were prepared by annealing the amorphous blends and were subsequently evaluated. By mixing PLLA and the compound consisting of POEGMA and PMMA using a two-roll mill, a blend with a maximum ionic conductivity of ~1.1 × 10–7 S cm−1 was obtained. The scanning electron microscopy results indicated that the ionic conductive phases were finely dispersed within the blends. By comparing the storage modulus values of the crystallized blends to those of amorphous blends, we found that the crystallized blends were harder at approximately the glass transition temperature of PLLA. We prepared ionic conductive compound (ICC) by solution casting and the in situ polymerization of poly(ethylene glycol) methyl ether methacrylate (OEGMA) in the presence of PMMA and a cross-linking agent. Then, ionic conductive polymer blends was obtained by melt-mixing ICC and poly(L-lactic acid) (PLLA). We studied the relationship between phase structure and physical properties such as electrical and mechanical properties of the blends.

Studies on transport properties of manganite based nano–micro particles–matrix composites

In this communication, low resistive bulk La0.7Ca0.3MnO3 (LCMO) was prepared by solid state reaction (SSR) route whereas high resistive nanoparticles of LaMnO3 (LMO) was prepared by cost effective sol–gel technique. Composites of LMO and LCMO were prepared by mixing them in different weight ratios, i.e. LMO = 10%, 20% and 30% in LCMO manganite matrix. In the present study, LMO have been used as nanoparticle fillers in the LCMO matrix lattice to study the transport properties of the composites. X–ray diffraction (XRD) measurement reveals the single phasic nature of the composites without any detectable impurity within the measurement range studied. XRD pattern of higher LMO content based composite possesses slightly different structural phases of LMO and LCMO. Resistivity measurement reveals that all the composites exhibit metal to insulator electronic phase transition at respective TP, wherein values of resistivity and TP get modified due to the cooling or heating cycles performed, measurement current used and LMO nanoparticle filler content in the composites. These variations have been discussed in the context of scattering centres created due to the presence of LMO fillers and complex phase separation scenario of the composites. A clear phase separation in higher filler content based composite has been displayed in its resistivity behaviour. To understand the charge transport mechanisms responsible for metallic and insulating (or semiconducting) regions in resistivity behaviours of the composites, most suitable zener double exchange polynomial law and Mott type variable range hopping mechanism were fitted theoretically to the obtained experimental results. Fittings show that spin fluctuations in the composites are highly dependent on the cycles performed, current applied and LMO nanoparticle filler content in the composites. Applied negative and positive current and voltage dependent resistance of the composites reveal the negative electroresistance. Both, resistance of the composites as well as electroresistance are highly affected by the cycles performed, current applied and LMO nanoparticle filler content in the composites understudy. Temperature dependent electroresistance was studied for better insight into an active role of phase separation near electronic phase transition temperatures for all manganite based composites.

Tunable electrical conductivity of polystyrene/polyamide-6/carbon nanotube blend nanocomposites via control of morphology and nanofiller localization

The electrical conductivity and percolation behavior of polymer blend nanocomposites were investigated asa consequence of polymer-filler interaction and blend morphology. The nanocomposites were derived from melt compounding of carbon nanotubes (CNTs) in polystyrene (PS)/polyamide 6 (PA6) blends. The electrical conductivity of co-continuous PS/PA6 (50/50) blends remained constant in the semi-conductive region (6.75×10−8–1.50×10−7S·cm−1) over a wide range of CNT loading (0.5–3.5 phr). Nevertheless, (50/50) blends presented higher electrical conductivity than PA6/CNT nanocomposites with the same effective CNT concentration. Contrary to common intuitions, at high loadings of CNTs, higher electrical conductivity was observed for the blends wherein the CNT-rich PA6 phase was in the form of dispersed droplet morphology rather than co-continuous one. For instance, at the CNT loading of 3.5 phr, the conductivity of blend with PS/PA6 volume ratio of (90/10) is approximately 4 orders of magnitude higher than co-continuous (50/50) blend. This observation is attributed to a two-level percolation mechanism (primary and secondary), as verified by optical and transmission electron microscopy. The primary percolation occurs by selective localization of CNTs in PA6 droplets due to their thermodynamic affinity for the PA6 phase. Once the PA6 droplets are impregnated with CNTs, the excess CNTs (at high loadings) localize in the PS phase and act as effective electrical bridges for the highly conductive PA6 droplets (secondary percolation).

Zonal flow magnetic field interaction in the semi-conducting region of giant planets

All four giant planets in the Solar System feature zonal flows on the order of 100 m/s in the cloud deck, and large-scale intrinsic magnetic fields on the order of 1 Gauss near the surface. The vertical structure of the zonal flows remains obscure. The end-member scenarios are shallow flows confined in the radiative atmosphere and deep flows throughout the entire planet. The electrical conductivity increases rapidly yet smoothly as a function of depth inside Jupiter and Saturn. Deep zonal flows will inevitably interact with the magnetic field, at depth with even modest electrical conductivity. Here we investigate the interaction between zonal flows and magnetic fields in the semi-conducting region of giant planets. Employing mean-field electrodynamics, we show that the interaction will generate detectable poloidal magnetic field perturbations spatially correlated with the deep zonal flows. Assuming the peak amplitude of the dynamo α-effect to be 0.1 mm/s, deep zonal flows on the order of 0.1–1 m/s in the semi-conducting region of Jupiter and Saturn would generate poloidal magnetic perturbations on the order of 0.01%–1% of the background dipole field. These poloidal perturbations should be detectable with the in-situ magnetic field measurements from the Juno mission and the Cassini Grand Finale. This implies that magnetic field measurements can be employed to constrain the properties of deep zonal flows in the semi-conducting region of giant planets.

Linear magnetoresistance in a topological insulator Ru2Sn3

We have studied magnetotransport properties of a topological insulator material Ru2Sn3. Bulk single crystals of Ru2Sn3 were grown by a Bi flux method. The resistivity is semiconducting at high temperatures above 160 K, while it becomes metallic below 160 K. Nonlinear field dependence of Hall resistivity in the metallic region shows conduction of multiple carriers at low temperatures. In the high-temperature semiconducting region, magnetoresistance exhibits a conventional quadratic magnetic-field dependence. In the low-temperature metallic region, however, high-field magnetoresistance is clearly linear with magnetic fields, signaling a linear dispersion in the low-temperature electronic structure. Small changes in the magnetoresistance magnitude with respect to the magnetic field angle indicate that bulk electron carriers are responsible mainly for the observed linear magnetoresistance.

New family of graphene-based organic semiconductors: An investigation of photon-induced electronic structure manipulation in half-fluorinated graphene

The application of graphene to electronic and optoelectronic devices is limited by the absence of reliable semiconducting variants of this material. A promising candidate in this respect is graphene oxide, with a band gap on the order of $\ensuremath{\sim}5\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$, however, this has a finite density of states at the Fermi level. Here, we examine the electronic structure of three variants of half -fluorinated carbon on Sic(0001), i.e., the $(6\sqrt{3}\ifmmode\times\else\texttimes\fi{}6\sqrt{3})$ $R{30}^{\ensuremath{\circ}}$ C/SiC ``buffer layer,'' graphene on this $(6\sqrt{3}\ifmmode\times\else\texttimes\fi{}6\sqrt{3})$ $R{30}^{\ensuremath{\circ}}$ C/SiC buffer layer, and graphene decoupled from the SiC substrate by hydrogen intercalation. Using angle-resolved photoemission, core level photoemission, and x-ray absorption, we show that the electronic, chemical, and physical structure of all three variants is remarkably similar, exhibiting a large band gap and a vanishing density of states at the Fermi level. These results are explained in terms of first-principles calculations. This material thus appears very suitable for applications, even more so since it is prepared on a processing-friendly substrate. We also investigate two separate UV photon-induced modifications of the electronic structure that transform the insulating samples (6.2-eV band gap) into semiconducting ($\ensuremath{\sim}2.5$-eV band gap) and metallic regions, respectively.

Synthesis and characterization of a conductive, biodegradable polyurethane elastomer

Event Abstract Back to Event Synthesis and characterization of a conductive, biodegradable polyurethane elastomer Cancan Xu1, 2, Fuqiang Liu3, Alejandro Bugarin4 and Yi Hong1, 2 1 University of Texas at Arlington, Department of Bioengineering, United States 2 University of Texas Southwestern Medical Center at Dallas, Joint Biomedical Engineering Program, United States 3 University of Texas at Arlington, Department of Material Science and Engineering, United States 4 University of Texas at Arlington, Department of Chemistry and Biochemistry, United States Introduction: Biodegradable conductive materials have promises to be applied for myocardium, nerve, muscle and bone tissue repair. The conductive hydrogel promoted growth and maturation of cardiac cells, and enhanced the electrical and mechanical coupling and contractile properties[1]. The conductive material also improved neurite outgrowths from the nerve cells by integrating biochemical and electrical stimulations[2]. However, biodegradable conductive elastomer was rarely reported. To address this limitation, we will utilize polyurethane chemistry to design a biodegradable polymer with elasticity and conductivity. Here, we combined polycaprolactone diol (PCL) as a soft segment, 1, 6-hexamethylene diisocyante (HDI) as a hard segment and aniline trimer as a chain extender to achieve a biodegradable polyurethane with electrical and electrochemical properties. The electrical and electrochemical properties, morphologies, mechanical properties, degradation behavior, electrical stability and cytocompatibility of the conductive polyurethane were evaluated. Materials and Methods: The conductive polyurethane (CPU) was synthesized by a two-step process (Fig. 1) and then fabricated into films doped with (1S)-(+)-10-camphorsulfonic acid (CSA) by solvent casting. The chemical structures of oxidized aniline trimer and CPU films were confirmed by 1H NMR, 13C NMR and FTIR, respectively. The morphologies of CPU films were observed on a scanning electron microscope (SEM). The electrical conductivities of CPU films at dry and wet states were measured by four-probe technique. The electroactivities of CPU films were characterized by UV-vis and cyclic voltammogram measurements. Mechanical properties of CPU films were measured on a MTS workstation with a head crossing rate of 10 mm/min. Cyclic stretching of CPU films at a maximum strain of 30% was tested at a constant rate of 10 mm/min for 10 cycles. The electrical stability of doped CPU films was carried out in cell culture medium under a constant DC voltage of 100±2 mV for 150 h. In vitro degradation of CPU films was detected in phosphate buffer solution (PBS) and lipase/PBS solutions. The electrical conductivity changes of CPU films were measured after degradation in 100 U/mL lipase/PBS solution for 3 and 7 d at 37 oC. The cytocompatibility of CPU films was evaluated using 3T3 fibroblasts. Results and Discussion: All CPU films showed good elasticity within 30% strain range, and their initial moduli increased with increasing CSA content. The roughness of CPU films increased with increasing CSA amount. The electrical conductivity of CPU films also enhanced with increasing CSA dopant amount, ranging from 2.7±0.9×10-10 to 4.4±0.6×10-7 S/cm at dry state and 4.2±0.5×10-8 to 7.3±1.5×10-5 S/cm at wet state. These values (wet) were in the semiconductive region. The redox peaks (0.17 V and 0.82 V) of CPU1.5 film (molar ratio of CSA:aniline trimer was 1.5:1) in cyclic voltammogram indicated its good electroactivity. The doped CPU film exhibited excellent electrical stability (91% of initial conductivity after 150 h charge) in cell culture medium. The degradation of CPU films became faster with increasing CSA dopant amount in either PBS or lipase/PBS solutions. After 7 d of enzymatic degradation, all CSA doped CPU films lost their conductivity. Their conductivities were similar to that of the undoped CPU film, which may attribute to the dopant leaching during degradation. The 3T3 fibroblasts proliferated and spread on all CPU films. There was no significantly difference on cell proliferation between CPU films and the tissue culture polystyrene, except for the CPU1.5 film. The CPU1.5 film having the highest dopant content showed less cell viability within 5 d incubation, which may be resulted from the rough surface and leached dopant. Conclusions: A biodegradable conductive polyurethane containing aniline trimer was synthesized. They had good elasticity conductive stability and biocompatibility, which are closely relevant with dopant amount. This biodegradable conductive polyurethane would find opportunities to be applied as tissue engineered scaffolds and smart drug release carriers. Research Enhancement Program from UT Arlington; Beginning-in-Aid award (#14BGIA20510066) from the American Heart Association

Thermally Conductive Adhesive from Chemically Modified Cellulose and Nanoparticle of Surfactant‐Doped Polypyrrole

SummaryNanocomposite of thermally conductive adhesive was prepared from cellulose‐based adhesive, TSA‐doped Ppy and ceramic filler via colloidal dispersion. Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to characterize the nanocomposites. Electrical and thermal conductivity were measured by using frequency response analyzer and thermal analyzer, respectively. Results showed that the prepared thermally conductive adhesive was stable at relatively high temperature. The electrical conductivity found for the nanocomposite was in the range of semi conductive region. Meanwhile, the thermal conductivity was higher than the conventional polymer.

Effect of nitrile groups on conductivity and morphology of NBR/polyether-based electrolyte blends for antistatic materials

Ion-conductive elastomer blends of commercial acrylonitrile-butadiene rubbers (NBR) rubber with polyether-based electrolyte were prepared as potential antistatic materials. Polyether-based electrolytes are usually very sensitive to humidity, because the electrolyte consists of hydrophilic polyether and metal salt. Here, we generated a nano-ordered phase-separated structure in the NBR blends so as to improve their stability against varying humidity environment. For better control of the conductivity in the semi-conductive region under differing conditions, we prepared NBR/polyether-based electrolyte blends with differing acrylonitrile (AN) content of NBR, and studied the effects of CN groups on the conductive properties and structures using a DC conductivity system, differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). We found that the conductivity of the blends increased with increasing AN content of NBR, implying that CN groups having strong electron withdrawing properties interact with the dissociated K ions. The FT-IR and TEM measurements show that the concentration of the CN groups is a crucial factor in determining the morphology of each blends and the improvement in conductivity between the NBR and polyether phases.