Showing papers on "Polymer blend published in 2018"

Morphology Optimization via Side Chain Engineering Enables All-Polymer Solar Cells with Excellent Fill Factor and Stability.

Abstract: All-polymer solar cells (all-PSCs) composed of conjugated polymers as both donor and acceptor components in bulk heterojunction photoactive layers have attracted increasing attention. However, it is a big challenge to achieve optimal morphology in polymer:polymer blends. In response, we report herein a new strategy to adjust the nanoscale organization for all-PSCs. Specifically, side chain engineering of the well-known naphthalene diimide (NDI)-based polymer N2200 is modulated by introducing a fraction of linear oligoethylene oxide (OE) side chains to replace branched alkyl chains on the NDI units and by synthesizing a series of NDI-based polymer acceptors NOEx, where x is the percentage of OE chain substituted NDI units relative to total NDI units. Compared to the reference polymer NOE0, OE-chain-containing polymer NOE10 offers a much higher power conversion efficiency (PCE) of 8.1% with a record high fill factor (FF) of 0.75 in all-PSCs. Moreover, the NOE10-based all-PSC exhibits excellent long-term and...

Recent Advances in Poly(vinylidene fluoride) and Its Copolymers for Lithium-Ion Battery Separators

Abstract: The separator membrane is an essential component of lithium-ion batteries, separating the anode and cathode, and controlling the number and mobility of the lithium ions. Among the polymer matrices most commonly investigated for battery separators are poly(vinylidene fluoride) (PVDF) and its copolymers poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and poly(vinylidene fluoride-cochlorotrifluoroethylene) (PVDF-CTFE), due to their excellent properties such as high polarity and the possibility of controlling the porosity of the materials through binary and ternary polymer/solvent systems, among others. This review presents the recent advances on battery separators based on PVDF and its copolymers for lithium-ion batteries. It is divided into the following sections: single polymer and co-polymers, surface modification, composites, and polymer blends. Further, a critical comparison between those membranes and other separator membranes is presented, as well as the future trends on this area.

Biobased Structurally Compatible Polymer Blends Based on Lignin and Thermoplastic Elastomer Polyurethane as Carbon Fiber Precursors

Abstract: The production of carbon fibers based on lignin reduces the cost and the environmental impact associated with carbon fiber manufacturing. However, the melt processing of lignin as a carbon fiber precursor is challenging due to its brittleness and limited thermoplastic behavior. For this reason we produce biopolymer blends based on Alcell organosolv hardwood lignin, hydroxypropyl modified Kraft hardwood, and a thermoplastic elastomer polyurethane (TPU). Samples with TPU content greater than 30% showed excellent melt processability and carbonization yield (35% carbon yield for the samples containing 30% of TPU). The thermal properties were analyzed by differential scanning calorimetry, rheology and thermogravimetric analysis. Fourier infrared measurements were utilized to explain the lignin/TPU interactions which governed the thermal and rheological behavior of the blends. SEM analysis showed that the blends produce a homogeneous structure which was void free after carbonization. These structurally compleme...

Semiconducting polymer blends that exhibit stable charge transport at high temperatures

Abstract: Although high-temperature operation (i.e., beyond 150°C) is of great interest for many electronics applications, achieving stable carrier mobilities for organic semiconductors at elevated temperatures is fundamentally challenging. We report a general strategy to make thermally stable high-temperature semiconducting polymer blends, composed of interpenetrating semicrystalline conjugated polymers and high glass-transition temperature insulating matrices. When properly engineered, such polymer blends display a temperature-insensitive charge transport behavior with hole mobility exceeding 2.0 cm2/V·s across a wide temperature range from room temperature up to 220°C in thin-film transistors.

Remarkable Enhancement of the Hole Mobility in Several Organic Small-Molecules, Polymers, and Small-Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p-Dopant B(C6F5)3.

Abstract: Improving the charge carrier mobility of solution-processable organic semiconductors is critical for the development of advanced organic thin-film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small-molecules, polymers, and small-molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C6F5)3 in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C6F5)3 is shown to have a remarkable impact are the blends of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF-TESADT:PTAA) and 2,7-dioctyl[1]-benzothieno[3,2-b][1]benzothiophene:poly(indacenodithiophene-co-benzothiadiazole) (C8-BTBT:C16-IDTBT), for which hole mobilities of 8 and 11 cm2 V-1 s-1, respectively, are obtained. Doping of the 6,13-bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C6F5)3 is also shown to increase the maximum hole mobility to 3.7 cm2 V-1 s-1. Analysis of the single and multicomponent materials reveals that B(C6F5)3 plays a dual role, first acting as an efficient p-dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p-doping and dopant-induced long-range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics.

Machine learning-based screening of complex molecules for polymer solar cells.

Abstract: Polymer solar cells admit numerous potential advantages including low energy payback time and scalable high-speed manufacturing, but the power conversion efficiency is currently lower than for their inorganic counterparts. In a Phenyl-C_61-Butyric-Acid-Methyl-Ester (PCBM)-based blended polymer solar cell, the optical gap of the polymer and the energetic alignment of the lowest unoccupied molecular orbital (LUMO) of the polymer and the PCBM are crucial for the device efficiency. Searching for new and better materials for polymer solar cells is a computationally costly affair using density functional theory (DFT) calculations. In this work, we propose a screening procedure using a simple string representation for a promising class of donor-acceptor polymers in conjunction with a grammar variational autoencoder. The model is trained on a dataset of 3989 monomers obtained from DFT calculations and is able to predict LUMO and the lowest optical transition energy for unseen molecules with mean absolute errors of 43 and 74 meV, respectively, without knowledge of the atomic positions. We demonstrate the merit of the model for generating new molecules with the desired LUMO and optical gap energies which increases the chance of finding suitable polymers by more than a factor of five in comparison to the randomised search used in gathering the training set.

Reactive extrusion of bio-based polymer blends and composites – Current trends and future developments

Abstract: Reactive extrusion is a cost-effective and environmentally-friendly method to produce new materials with enhanced performance properties. At present, reactive extrusion allows in-situ polymerization, modification/functionalization of polymers or chemical bonding of two (or more) immiscible phases, which can be carried out on commonly used extrusion lines. Although reactive extrusion has been known for many years, its application for processing of bio-based polymer blends and composites is a relatively new direction of scientific research. This work presents a literature review on recent advances in the processing of bio-based polymer blends and composites via reactive extrusion. We described compatibilization mechanisms for different types of biodegradable polymeric materials based on: (i) aliphatic polyesters, (ii) aliphatic polyesters/starch and (iii) aliphatic polyester/natural rubber systems. A special attention was focused on conventional and dynamic cross-linking of bio-based polymer blends and composites as an effective way to prepare new materials with unique properties e.g. biodegradable thermoplastic elastomers or shape-memory materials. Advantages and limitations affecting future trends in development of biodegradable polymer blends and composites reactive extrusion are also discussed.

Single-ion Homopolymer Electrolytes with High Transference Number Prepared by Click Chemistry and Photoinduced Metal-free ATRP

Abstract: Solvent-free single-ion polymer electrolytes with high conductivity have historically been prepared in the form of block copolymer or polymer blends. In this work, single-ion homopolymer electrolytes consisting of poly(poly(ethylene oxide) methacrylate lithium sulfonyl(trifluoromethylsulfonyl)imide), poly(PEOMA-TFSI-Li+), were prepared for the first time by photoinduced metal-free atom-transfer radical polymerization (ATRP). The PEO-based macromonomer PEOMA-TFSI-Li+ was synthesized via click chemistry - copper-catalyzed alkyne-azide cycloaddition (CuAAC). Due to the conductive, amorphous PEO phase in which the lithium ions are located, these polymers showed improved ionic conductivity (10-5 ~ 10-4 S/cm at 90 oC) and high transference number (0.97 ~0.99). The potential dendrite suppressing capability of the polyelectrolytes was estimated by employing a kinetic model using the measured transport and transference properties to study the current density at the dendrite tip. The analysis indicates that the syn...

Enhanced Interfacial Adhesion by Reactive Carbon Nanotubes: New Route to High-Performance Immiscible Polymer Blend Nanocomposites with Simultaneously Enhanced Toughness, Tensile Strength, and Electrical Conductivity.

Abstract: Physically anchoring carbon nanotubes (CNTs) onto the interface of immiscible polymer blends has been extensively reported; however, enhancement of physical properties of the blends has seldom been achieved. Herein, we used CNTs with reactive epoxide groups and long poly(methyl methacrylate) (PMMA) tails as a thermodynamic compatibilizer for immiscible poly vinylidene fluoride/poly l-lactide (PVDF/PLLA) blends. The CNTs acted as an efficient compatibilizer and bridged the two phases through physical entanglement and chemical reaction. The sea–island structure of the blend transformed into a bicontinuous structure for CNT contents greater than 3 wt %. The mechanical properties, including ductility and tensile strength, thermal properties, and electrical conductivities were all enhanced by the CNTs compatibilizer. This strategy thermodynamically compatibilized by reactive nanofillers paves the way for advanced blend nanocomposites.

Structural, Optical and Thermal Characterizations of PVA/MAA:EA Polyblend Films

Abstract: Films of polyvinyl alcohol (PVA), Methacrylic Acid - Ethyl Acrylate (MAA:EA) copolymer and their blends PVA:MAA:EA of composition 80:20, 60:40, 50:50, 40:60, 20:80 (wt %) were prepared by using the solution cast technique. The prepared films were investigated by structural, optical and thermal studies. X-ray diffraction (XRD) scans revealed the semicrystalline nature of the blends for lower concentrations of PVA up to 60 wt % and the amorphous nature for higher ones. Fourier transform infra-red spectroscopy (FTIR) of blend samples indicates that there is a compatibility between PVA and MAA:EA copolymers through the formation of hydrogen-bonding between their polar groups.SEM image of polymer blend suggested the presence structural reorganization of polymer chains. UV-Visible spectral analysis revealed that the intensity of the shoulder around 271 nm decreases with increasing MAA:EA content. In DSC analysis, a single glass transition temperature for each blend was observed, which supports the existence of compatibility of such systems. From the observed results, 50:50 (wt %) PVA/MAA:EA is found to be the optimum blending ratio.

Evaluation of structural and optical properties of Ce 3+ ions doped (PVA/PVP) composite films for new organic semiconductors

Abstract: Polymer blend films based on Polyvinyl alcohol (PVA)/Poly(vinylpyrrolidone) (PVP) doped with different concentration of cerium ions [(PVA/PVP)-x wt.% Ce3+] (x = 3%, 5%, 10% and 15%) were prepared by the conventional solution casting technique. The characteristics of the prepared polymer composite films were studied using X-ray diffraction (XRD), FT-IR and UV–Vis. spectroscopy. The XRD patterns of the investigated samples revealed a clear reduction on the structural parameters such as crystallinity degree and cluster size D of the doped PVA/PVP blend films compared with the virgin one whereas there is no big difference in the d spacing of the product composite films. Significant changes in FT-IR spectra are observed which reveal an interactions between the cerium ions and PVA/PVP blends. The absorption spectra in the ultraviolet–visible region showed a wide red shift in the fundamental absorption edge of (PVA/PVP)-x wt. % Ce3+ composites. The optical gap Eg gradually decreased from 4.54 eV for the undoped PVA/PVP film to 3.10 eV by increasing Ce3+ ions content. The optical dispersion parameters have been analyzed according to Wemple–Didomenico single oscillator model. The dispersion energy Ed, the single oscillator energy Eo, the average inter-band oscillator wavelength λo and the static refractive index no are strongly affected by cerium ions doping. Cerium ions incorporation in PVA/PVP blend films leads to a significant increase in the refractive index and decrease in the optical gap. These results are likely of great important in varieties of applications including polymer waveguides, organic semiconductors, polymer solar cells and optoelectronics devices.

Characterization of amorphous silica nanofiller effect on the structural, morphological, optical, thermal, dielectric and electrical properties of PVA–PVP blend based polymer nanocomposites for their flexible nanodielectric applications

Abstract: The biodegradable polymers blend matrix of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend (50/50 wt%) dispersed with amorphous silica (SiO2) nanoparticles based polymer nanocomposite (PNC) films (i.e., (PVA–PVP)–x wt% SiO2; x = 0, 1, 3 and 5) were prepared by the aqueous solution-cast method. These PNC films were characterized by employing the X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, differential scanning calorimetry and dielectric relaxation spectroscopy techniques. It is found that the dispersion of nanosize SiO2 particles in the PVA–PVP blend matrix reduces the size of PVA crystallites and, turns the surface morphology from smooth into porous and relatively rough for the PNC films. The SiO2 interaction with polymer structure significantly alters the polymer–polymer interactions, reduces the optical band gap and the glass phase transition temperature, and enhances the melting phase transition temperature of the polymer blend films. The dielectric permittivity of the PNC films initially decreases with the increase of SiO2 contents up to 3 wt%, but at 5 wt% SiO2 concentration it is found nearly same as that of the pristine polymer blend matrix. The ac conductivity of these PNC films increases with the increase of frequency according to the power law relation. The dielectric permittivity exhibits non-linear increase with the increase of temperature of the PNC film whereas its dc conductivity obeys the Arrhenius behaviour. The dielectric and electrical properties of these PNC films realize their suitability as low-permittivity and low loss novel nanodielectrics for the substrate and insulator in the development of various microelectronic and organo-electronic devices.

Kinetic Control of Graphene Localization in Co-continuous Polymer Blends via Melt Compounding.

Abstract: Selective localization of graphene in co-continuous polymer blends is an attractive method for preparing conductive polymer composites. Localization of graphene at the interface between the two polymer phases produces good conductivity at ultra-low concentrations. Although graphene localization is ultimately dependent on thermodynamic factors such as the surface energy of graphene and the two polymer components, kinetics also strongly affects the migration and localization of graphene in polymer blends during melt compounding. However, few studies have systemically investigated the important role of kinetics on graphene localization. Here, we introduced graphene nanoplatelets (GNPs) in polylactic acid (PLA)/polystyrene (PS) co-continuous polymer blends. Although GNPs in thermal equilibrium prefer the PS phase, we were able to kinetically trap GNPs at the interface of polymer blends via control of melt-compounding sequences, mixing times and shear rates. Utilizing morphological, rheological, and electrical...

Structural and phase separation characterization of poly(lactic acid)/poly(ethylene oxide)/carbon nanotube nanocomposites by rheological examinations

Abstract: The morphology and phase separation have significant impacts on the properties and applications of polymer blends and nanocomposites. In this study, poly(lactic acid) (PLA)/poly(ethylene oxide) (PEO) blends and PLA/PEO/carbon nanotube (CNT) nanocomposites are prepared by solution mixing and the rheological approach is applied to study the morphology and phase separation of the prepared samples. Scanning electron microscopy (SEM) is also used to study the morphology and structure of samples. Additionally, the miscibility or immiscibility between polymer blends was analyzed through Han plots. The results display the lower critical solution temperature (LCST) phase diagram for the prepared samples demonstrating that the enhancement of temperature promotes phase separation. Moreover, the addition of nanoparticles transfers the LCST diagram to high temperatures. The deformation relaxation of PEO droplets commonly diminishes the modulus at very low frequencies, while the formation of big CNT networks in nanocomposites containing high CNT content results in a constant modulus. Han plots also represent the immiscibility in the samples containing 60 and 75 wt% PLA and the nanocomposites including 90 wt% PLA show homogenous structures. The SEM images verify the outputs of rheological tests conducted for the morphology of samples.

Novel of (polymer blend-Fe 3 O 4 ) magnetic nanocomposites: preparation and characterization for thermal energy storage and release, gamma ray shielding, antibacterial activity and humidity sensors applications

Abstract: Preparation of (PVA-PEG-PVP-Fe3O4) magnetic nanocomposites and studying their structural, electrical and optical properties have been investigated. The results showed that the D.C., A.C. electrical and optical properties of (PVA-PEG-PVP) blend are improved with increase in Fe3O4 nanoparticles concentration. The (PVA-PEG-PVP-Fe3O4) nanocomposites tested for thermal energy storage and release, gamma ray shielding, antibacterial activity and humidity sensors applications with high quality, lightweight and good elastic. The results of showed that the melting and solidification time for thermal energy storage and release decrease with adding Fe3O4 nanoparticles concentrations. The attenuation coefficients of gamma radiation increase with increase in nanoparticles concentration. The inhibition zone for antibacterial application increases with increase in Fe3O4 nanoparticles concentration. The nanocomposites have highly sensitivity for humidity.

Investigation of ionic conduction in PEO-PVDF based blend polymer electrolytes

Abstract: We investigate the effect of blend host polymer on solid polymer electrolyte (SPE) films doped with ammonium iodide (NH4I) salt using a variety of experimental techniques. Structural studies on the composite SPEs show that the blending of Poly(ethylene oxide) (PEO)–Poly(vinylidene fluoride) (PVDF) polymers in a suitable ratio enhances the amorphous fraction of the polymer matrix and facilitates fast ion conduction through it. We observe that the addition of a small amount of PVDF in the PEO host polymer enhances the ion – polymer interaction leading to more ion dissociation. As a result, the effective number of mobile charge carriers within the polymer matrix increases. Systematic investigation in these blend SPEs shows that the maximum conductivity (1.01 × 10–3 S/cm) is obtained for PEO – rich (80 wt. % PEO, 20 wt. % PVDF) composites at 35 wt. % NH4I concentration at room temperature. Interestingly, at higher salt concentrations (above 35 wt. %), the conductivity is found to decrease in this system. The reduction of conductivity at higher salt concentrations is the consequence of decrease in the carrier concentration due to the formation of an ion pair and ion aggregates. PVDF–rich compositions (20 wt. % PEO and 80 wt. % PVDF), on the other hand, show a very complex porous microstructure. We also observe a much lower ionic conductivity (maximum ∼ 10–6 S/cm at 15 wt. % salt) in these composite systems relative to PEO-rich composites.

Enhancing Impact Resistance of Polymer Blends via Self-Assembled Nanoscale Interfacial Structures

Abstract: We have designed and engineered an environmentally sustainable ternary polymer blend with the mechanical properties comparable to high impact resistant conventional polymers under the guidance of the lattice self-consistent field model. In this blend system, poly(methyl methacrylate) (PMMA) was used as the compatibilizer for the poly(lactic acid) (PLA)/poly(butylene adipate-co-butylene terephthalate) (PBAT) blend. We characterized the compatibility of those components and found PMMA was miscible with PLA and partially compatible with PBAT, which allowed it to self-assemble to a nanoscale interfacial layer on the PLA/PBAT interface. This PMMA layer can significantly decrease the interfacial energy and strongly entangle with either PLA or PBAT, resulting in the strengthening of the interface and dramatically enhancement of the impact resistance of the ternary blend. The optimal mechanical performance was achieved when the total PMMA concentration was less than 10 wt %. Higher PMMA content embrittled the ble...

Electrical Properties of Polyethylene/Polypropylene Compounds for High-Voltage Insulation

Abstract: In high-voltage insulation systems, the most commonly used material is polymeric material because of its high dielectric strength, high resistivity, and low dielectric loss in addition to good chemical and mechanical properties. In this work, various polymer compounds were prepared, consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), HDPE/PP, and LDPE/PP polymer blends. The relative permittivity and breakdown strength of each sample types were evaluated. In order to determine the physical properties of the prepared samples, the samples were also characterized using differential scanning calorimetry (DSC). The results showed that the dielectric constant of PP increased with the increase of HDPE and LDPE content. The breakdown measurement data for all samples were analyzed using the cumulative probability plot of Weibull distribution. From the acquired results, it was found that the dielectric strengths of LDPE and HDPE were higher than that of PP. Consequently, the addition of LDPE and HDPE to PP increased the breakdown strength of PP, but a variation in the weight ratio (30%, 50% and 70%) did not change significantly the breakdown strength. The DSC measurements showed two exothermic crystallization peaks representing two crystalline phases. In addition, the DSC results showed that the blended samples were physically bonded, and no co-crystallization occurred in the produced blends.

Green electrolytes based on dextran-chitosan blend and the effect of NH 4 SCN as proton provider on the electrical response studies

Abstract: Dextran-chitosan blend added with ammonium thiocyanate (NH4SCN)-based solid polymer electrolytes are prepared by solution cast method. The interaction between the components of the electrolyte is verified by Fourier transform infrared (FTIR) analysis. The blend of 40 wt% dextran-60 wt% chitosan is found to be the most amorphous ratio. The room temperature conductivity of undoped 40 wt% dextran-60 wt% chitosan blend film is identified to be (3.84 ± 0.97) × 10−10 S cm−1. The inclusion of 40 wt.% NH4SCN to the polymer blend has optimized the room temperature conductivity up (1.28 ± 0.43) × 10−4 S cm−1. Result from X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis shows that the electrolyte with the highest conductivity value has the lowest degree of crystallinity (χ c) and the glass transition temperature (T g), respectively. Temperature-dependence of conductivity follows Arrhenius theory. From transport analysis, the conductivity is noticed to be influenced by the mobility (μ) and number density (n) of ions. Conductivity trend is further verified by field emission scanning electron microscopy (FESEM) and dielectric results.

Contrasting Effects of Energy Transfer in Determining Efficiency Improvements in Ternary Polymer Solar Cells

Abstract: © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Crystallizable, high-mobility conjugated polymers have been employed as secondary donor materials in ternary polymer solar cells in order to improve device efficiency by broadening their spectral response range and enhancing charge dissociation and transport. Here, contrasting effects of two crystallizable polymers, namely, PffBT4T-2OD and PDPP2TBT, in determining the efficiency improvements in PTB7-Th:PC 71 BM host blends are demonstrated. A notable power conversion efficiency of 11% can be obtained by introducing 10% PffBT4T-2OD (relative to PTB7-Th), while the efficiency of PDPP2TBT-incorporated ternary devices decreases dramatically despite an enhancement in hole mobility and light absorption. Blend morphology studies suggest that both PffBT4T-2OD and PDPP2TBT are well dissolved within the host PTB7-Th phase and facilitate an increased degree of phase separation between polymer and fullerene domains. While negligible charge transfer is determined in binary blends of each polymer mixture, effective energy transfer is identified from PffBT4T-2OD to PTB7-Th that contributes to an improvement in ternary blend device efficiency. In contrast, energy transfer from PTB7-Th to PDPP2TBT worsens the efficiency of the ternary device due to inefficient charge dissociation between PDPP2TBT and PC 71 BM.

Polyvinylidene fluoride (PVDF)/polyacrylonitrile (PAN)/carbon nanotube nanocomposites for energy storage and conversion

Abstract: Polyvinylidene fluoride (PVDF)/polyacrilonitrile (PAN)/multiwalled carbon nanotubes functionalized COOH (MWCNTs-COOH) nanocomposites with different contents of MWCNTs were fabricated by using electrospinning and solution cast methods The interaction of the MWCNTs with the polymer blend was confirmed by a Fourier transform infrared (FTIR) spectroscopy study The dispersion of the MWCNTs in the polymer blend was studied by scanning electron microscopy The dispersion of the MWCNTs in the polymer matrix at different compositions has been examined by using scanning electron microscopy (SEM) Both individual and agglomerations of MWCNTs were evident Multiwalled carbon nanotubes are capable of enhancing the impedance and electrical conductivity of PVDF-PAN/MWCNTs in a wide frequency range at different temperatures Nanocomposites based on PVDF/PAN and MWCNTs as fillers show a significant enhancement in the electrical conductivity as a function of temperature In addition, PVDF/PAN with 558 wt% of MWCNTs has a much higher specific energy (1297Wh/kg) compared to that of PVDF/PAN (1557 Wh/kg)The results reveal that PVDF/PAN/MWCNTs composites have potential applications for nanogenerators, organic semiconductors, transducers, and electrical energy storage

Synthesis of Novel (Polymer Blend-Ceramics) Nanocomposites: Structural, Optical and Electrical Properties for Humidity Sensors

Abstract: Fabrication of novel nanocomposites films of (PVA–CMC) blend and (PVA–CMC) blend doped by niobium carbide nanoparticles has been investigated. The structural, optical and electrical properties of (PVA–CMC–NbC) nanocomposites for humidity sensors have been studied. The (PVA–CMC–NbC) nanocomposites were prepared with different concentrations of (polyvinyl alcohol and carboxyl methyl cellulose) and Niobium carbide nanoparticles. The experimental results of optical properties for (PVA–CMC–NbC) nanocomposites showed that the absorbance, absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constants and optical conductivity of (PVA–CMC) blend increase with increase in Niobium carbide nanoparticles concentrations. The transmittance and energy band gap decrease with increase in Niobium carbide nanoparticles concentrations. The DC electrical properties of (PVA–CMC–NbC) nanocomposites showed that the electrical conductivity of the blend increases with increase in NbC nanoparticles concentrations. The experimental results of novel (PVA–CMC–NbC) nanocomposites applications showed that the (PVA–CMC–NbC) nanocomposites have high sensitivity for relative humidity.

Decoding the Vertical Phase Separation and Its Impact on C8-BTBT/PS Transistor Properties.

Abstract: Disentangling the details of the vertical distribution of small semiconductor molecules blended with polystyrene (PS) and the contact properties are issues of fundamental value for designing strategies to optimize small-molecule:polymer blend organic transistors. These questions are addressed here for ultrathin blends of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) and PS processed by a solution-shearing technique using three different blend composition ratios. We show that friction force microscopy (FFM) allows the determination of the lateral and vertical distribution of the two materials at the nanoscale. Our results demonstrate a three-layer stratification of the blend: a film of C8-BTBT of few molecular layers with crystalline order sandwiched between a PS-rich layer at the bottom (a few nm thick) acting as a passivating dielectric layer and a PS-rich skin layer on the top (∼1 nm) conferring stability to the devices. Kelvin probe force microscopy (KPFM) measurements performed in operat...