Showing papers on "Polymer blend published in 2021"

Polymerized small molecular acceptor based all-polymer solar cells with an efficiency of 16.16% via tuning polymer blend morphology by molecular design.

Abstract: All-polymer solar cells (all-PSCs) based on polymerized small molecular acceptors (PSMAs) have made significant progress recently. Here, we synthesize two A-DA’D-A small molecule acceptor based PSMAs of PS-Se with benzo[c][1,2,5]thiadiazole A’-core and PN-Se with benzotriazole A’-core, for the studies of the effect of molecular structure on the photovoltaic performance of the PSMAs. The two PSMAs possess broad absorption with PN-Se showing more red-shifted absorption than PS-Se and suitable electronic energy levels for the application as polymer acceptors in the all-PSCs with PBDB-T as polymer donor. Cryogenic transmission electron microscopy visualizes the aggregation behavior of the PBDB-T donor and the PSMA in their solutions. In addition, a bicontinuous-interpenetrating network in the PBDB-T:PN-Se blend film with aggregation size of 10~20 nm is clearly observed by the photoinduced force microscopy. The desirable morphology of the PBDB-T:PN-Se active layer leads its all-PSC showing higher power conversion efficiency of 16.16%. Through development of non-fullerene acceptors, OPVs have reached efficiencies of 18%, yet the inadequate operational lifetime still poses a challenge for the commercialisation. Here, the authors investigate the origin of instability of NFA solar cells, and propose some strategies to mitigate this issue.

High-temperature polymers with record-high breakdown strength enabled by rationally designed chain-packing behavior in blends

Abstract: Summary Polymers with high dielectric breakdown strength (Eb) over a broad temperature range are vital for many applications. The presence of weak points, such as voids and free volume, severely limit the Eb of many high-temperature polymers. Here, we present a general strategy to reduce these weak points by exploiting interchain electrostatic forces in polymer blends. We show that the strong interchain electrostatic interaction between two high-temperature polymers in blends of polyimide (PI) with poly(ether imide) (PEI) yields an extended polymer chain conformation, resulting in dense chain packing and a corresponding decrease in weak spots in the polymers. This leads to a greater than 65% enhancement of Eb at room temperature and 35% enhancement at 200°C. In conjunction with results from blends of PI/poly(1,4-phenylene ether-sulfone) (PSU) and blends of PEI/PSU, we show that this previously unexplored molecular engineering strategy is efficient and straightforward in minimizing weak points in dielectric polymers.

Stable Co-Continuous PLA/PBAT Blends Compatibilized by Interfacial Stereocomplex Crystallites: Toward Full Biodegradable Polymer Blends with Simultaneously Enhanced Mechanical Properties and Crystallization Rates

Abstract: Constructing stable co-continuous morphology of commercial immiscible polymer blends remains an ongoing challenge in terms of complex presynthetic routes, multiple parameter dependency, and intrinsic instability of phase morphology. Herein, we demonstrate a full biodegradable polymer blend, poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate), where hitherto inaccessible co-continuous with asymmetric compositions (70/30) can be obtained with the assistance of interfacial stereocomplex crystallites (i-SCs) through reactive blending. By taking full advantages of this unprecedented compatibilizer, nanostructured co-continuous blends with synergistically enhanced comprehensive performance are achieved. First, due to the “rigid” i-SC, co-continuous morphology is induced through a simple melt blending procedure; second, considerable augmentation of the crystallization rate of the PLA matrix is accomplished on account of the in situ formed nucleation agent (i.e., i-SC); third, a super toughened material with simultaneously enhanced tensile strength, ductility, and impact strength can be acquired, resulting from the i-SC-induced co-continuous morphology; and fourth, i-SC can function as a “rigid” supporting layer between phases even above 200 °C, resulting in significantly enhanced morphology stability in melt. The versatile, facile, and practical strategy offers an industrially relevant technique to fabricate super-robust and fully biobased polymer materials.

Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development.

Abstract: (1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined.

Synthesis of the SWCNTs/TiO2 nanostructure and its effect study on the thermal, optical, and conductivity properties of the CMC/PEO blend

Abstract: The TiO2 NPs have been successfully synthesized by sol-gel method and the SWCNTs/TiO2 nanostructures have been fabricated by a simple mixing technique. By a solution casting process, pure CMC/PEO and SWCNTs/TiO2 nanohybrid doped CMC/PEO polymer blend films have been prepared. The influence of SWCNTs/TiO2 nanohybrid loading on the thermal, optical, and conductivity properties of the polymer blend has been discussed. The XRD pattern shows that the average crystallite size of the nanoparticles for TiO2 and SWCNTs/TiO2 is 20 nm and 15 nm, respectively, and a change in crystallinity was observed with an increase in doping. The interaction between CMC/PEO chains and SWCNTs/TiO2 nanohybrid is confirmed by FTIR spectra. The optical absorption spectrum shows that the energy gap reduces with the dopant increase. The miscibility between the CMC and PEO was confirmed by DSC thermograms. With an increase in dopant content, the TGA study demonstrates that the system's thermal stability improves. The maximum value of the blend's AC conductivity is 4.77 10−6 S/m, and by increasing the loading of SWCNTs/TiO2 to 3.2 (wt%) increased to 9.23 10−4 S/m. The conduction mechanism changed with SWCNTs/TiO2 loading from the correlated barrier hopping, in the prepared samples. Usage of these nanocomposite films in the semiconductor industry is encouraged by the observed improvements in optical, thermal, and AC conductivity.

Improving Fast and Safe Transfer of Lithium Ions in Solid-State Lithium Batteries by Porosity and Channel Structure of Polymer Electrolyte.

Abstract: Solid-state lithium batteries using solid polymer electrolytes can improve the safety and energy density of batteries. Smoother lithium-ion channels are necessary for solid polymer electrolytes with high ionic conductivity. The porosity and channel structure of the polymer film affect the transfer of lithium ions. However, their controllable synthesis remains a big challenge. Here, we developed a simple synthesis approach toward wrinkled microporous polymer electrolytes by combining the amphoteric (water solubility and organic solubility) polymer in three polymer blends. The homogeneous blend solution spontaneously wrinkled to vertical fold channels as the solvent evaporated. Two minor polymers, poly(vinyl pyrrolidone) (PVP) and polyetherimide (PEI), formed close stacks, and Janus PVP was dispersed in the poly(vinylidene fluoride) (PVDF) matrix. The interfacial tensions between the three polymers were different, so stress was produced when they solidified. The solvent was evaporated to the top layer of the polymers when the temperature increased. The bottom layer wrinkled owing to the stress during solidification. The evaporation of the solvent generated micropores to form the lithium-ion channel. They helped Li+ transference and created a wrinkled microporous PVDF-based polymer electrolyte, which achieved an ionic conductivity of 5.1 × 10-4 S cm-1 and a lithium-ion transference number of 0.51 at room temperature. Meanwhile, the good flame retardancy and tensile strength of the polymer electrolyte film can improve the safety of the battery. At 0.5C and room temperature, the batteries with a LiFePO4 cathode and the wrinkled microporous LiTFSI/PEI/PVP/PVDF electrolyte reached a high discharge specific capacity of 122.1 mAh g-1 at the 100th cycle with a Coulombic efficiency of above 99%. The results of tensile and self-extinguishing tests show that the polymer electrolyte film has good safety application prospects.

Biodegradable Poly(Butylene Adipate-Co-Terephthalate) and Thermoplastic Starch-Blended TiO2 Nanocomposite Blown Films as Functional Active Packaging of Fresh Fruit

Abstract: Biodegradable polymers can be used for eco-friendly, functional, active packaging to preserve food quality. Incorporation of titanium dioxide (TiO2) nanoparticles into polymer packaging enhances ethylene-scavenging activity and extends the shelf-life of fresh produce. In this study, TiO2 nanoparticles were incorporated into biodegradable poly(butylene adipate-co-terephthalate) (PBAT)- and thermoplastic cassava starch (TPS)-blended films to produce nanocomposite packaging via blown-film extrusion. The effects of TiO2 on morphology, packaging properties, and applications as functional packaging for fresh produce were investigated. Increased TiO2 in the film packaging increased amorphous starch content and hydrogen bonding by interacting with the TPS phase of the polymer blend, with negligible chemical interaction with the PBAT component and identical mechanical relaxation in the PBAT phase. Surface topography indicated void space due to non-homogeneous dispersion causing increased oxygen and carbon dioxide permeability. Homogeneous dispersion of fine TiO2 nanoparticles increased mechanical strength and reduced oxygen, carbon dioxide, and water vapor permeability. Films containing TiO2 also showed efficient oxygen-scavenging activity that removed residual oxygen from the package headspace dependent on the levels and morphology of nanoparticles in the film matrices. Banana fruit packaged in films containing TiO2 recorded slower darkening color change and enhanced shelf-life with increasing TiO2 content.

Fused Filament Fabrication 4D Printing of a Highly Extensible, Self-Healing, Shape Memory Elastomer Based on Thermoplastic Polymer Blends.

Abstract: A polymer blend with high extensibility, exhibiting both shape memory and self-healing, was 4D printed using a low-cost fused filament fabrication (FFF, or fused deposition modeling, FDM) 3D printer. The material is composed of two commercially available commodity polymers, polycaprolactone (PCL), a semi-crystalline thermoplastic, and polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS), a thermoplastic elastomer. The shape memory and self-healing properties of the blends were studied systematically through thermo-mechanical and morphological characterization, providing insight into the shape memory mechanism useful for tuning the material properties. In 3D-printed articles, the orientation of the semi-crystalline and micro-phase-separated domains leads to improvement of the shape memory property and extensibility of this material compared to compression-molded samples. By controlling the orientation of the printed fibers, we achieved a high strain at break over 1200%, outperforming previously reported flexible 4D-printed materials. The self-healing agent, PCL, enables the material to heal scratches and cracks and adhere two surfaces after annealing at 80 °C for 30 min. The high performance, multi-functionality, and potential scalability make it a promising candidate for a broad spectrum of applications, including flexible electronics, soft actuators, and deployable devices.

Electrochemical characteristics of solid state double-layer capacitor constructed from proton conducting chitosan-based polymer blend electrolytes

Abstract: This research is about the preparation of polymer blend electrolytes based on chitosan using solution cast technique Field emission scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) routes were utilized for studying morphological and structural properties, respectively Electrical impedance spectroscopy (EIS) was engaged for determining the direct current electrical conductivity of the films The ion association at the highest salt concentration was actually present as confirmed by EIS and FTIR achievements The sample surface displays the protrude salts at the highest salt concentration Proton conducting polymer electrolyte with NH4Br as H+ (proton) provider has been used in electric double-layer capacitor (EDLC) applications The highest conducting sample was used to fabricate EDLC The transference number measurement indicated that the sample is mostly includes ion charge carriers which are vital for application in electrochemical devices The linear sweep voltammetry study revealed that the decomposition of the sample takes place above 154 V The fabricated EDLC device was performed capacitive behavior, as it can be seen from the cyclic voltammetry (CV) plot Since no redox peaks have appeared, it can be concluded that the EDLC did not undergo either oxidation or reduction The acquired value of specific capacitance (1325 Fg−1) is considered to be of great interest from the application viewpoints

Effect of cashew shell biomass synthesized cardanol oil green compatibilizer on flexibility, barrier, thermal, and wettability of PLA/PBAT biocomposite films

Abstract: The bio-based polymer blend of polylactic acid (PLA)-polybutylene adipate-co-terephthalate (PBAT) incorporated with cashew shell biomass synthesized cardanol oil (CARD) was prepared by solution casting method. The various formulations were prepared with PLA/PBAT(90/10) polymer blend containing 1%, 3%, and 5 wt.% of cardanol oil. All the prepared PLA/PBAT films were subjected to characterization techniques such as surface morphology, Fourier transform infrared spectroscopy, mechanical, thermal stability, X-ray diffraction, film color, opacity, wettability, and antimicrobial properties. The FTIR and XRD results confirmed the effective miscibility and molecular interactions of cardanol oil in PLA/PBAT blend. Further, the results of TGA analysis showed thermal stability improvement in PLA/PBAT bio-based film by the addition of cardanol oil. The homogeneous distribution of cardanol oil droplets on the PLA/PBAT blend was confirmed by observed SEM and TEM images. The mechanical result proved that the addition of 5 wt.% of cardanol oil into the PLA/PBAT blend increases the elongation at break. Moreover the bio-based PLA/PBAT film shows good barrier against water vapor and a poor barrier against oxygen permeability. The presence of cardanol oil in the PLA/PBAT matrix helps to enhance the optical and wettability properties of prepared bio-based film. Finally, it is proved from the investigational results that the PLA/PBAT/cardanol biodegradable films may be recommended to use in food packaging applications wherever high flexibility, water vapor barrier, thermal stability, antibacterial resistance, and less water absorption properties are required.

A Polymer Blend Electrolyte Based on CS with Enhanced Ion Transport and Electrochemical Properties for Electrical Double Layer Capacitor Applications.

Abstract: The fabrication of energy storage EDLC in this work is achieved with the implementation of a conducting chitosan–methylcellulose–NH4NO3–glycerol polymer electrolyte system. The simple solution cast method has been used to prepare the electrolyte. The impedance of the samples was fitted with equivalent circuits to design the circuit diagram. The parameters associated with ion transport are well studied at various plasticizer concentrations. The FTIR investigation has been done on the films to detect the interaction that occurs among plasticizer and polymer electrolyte. To get more insights into ion transport parameters, the FTIR was deconvoluted. The transport properties achieved from both impedance and FTIR are discussed in detail. It was discovered that the transport parameter findings are in good agreement with both impedance and FTIR studies. A sample with high transport properties was characterized for ion dominancy and stability through the TNM and LSV investigations. The dominancy of ions in the electrolyte verified as the tion of the electrolyte is established to be 0.933 whereas it is potentially stable up to 1.87 V. The rechargeability of the EDLC is steady up to 500 cycles. The internal resistance, energy density, and power density of the EDLC at the 1st cycle are 53 ohms, 6.97 Wh/kg, and 1941 W/kg, respectively.

Effect of addition of TiO2 nanoparticles on structural and dielectric properties of polystyrene/polyvinyl chloride polymer blend

Abstract: The present study deals with the effect of the addition of pure titanium oxide nanoparticles (TiO2 NPs) prepared by the sol–gel technique on a polystyrene (PS)/polyvinylchloride (PVC) polymer blend of a composition of 50/50 wt. % using the casting method. X-ray diffraction (XRD), high-resolution transmission electron microscopy, field emission scanning electron microscopy, and energy dispersive x-ray analysis confirmed the preparation of TiO2 NPs in semi-spherical shapes, with the average particle size ranging from 7 to 22 nm. The structural, optical, and dielectric properties of the prepared polymer nanocomposite films are restudied using different tools. In addition, the dielectric properties are studied. XRD and Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy confirmed the complexation and interaction between the PS/PVC polymer blend and TiO2 NPs. HRSEM images reveal that TiO2 NPs appeared as white spots inside the spherical domain of PS/PVC matrices. Optical properties such as absorbance, reflection, bandgap energy, refractive index, and optical dielectric (constant and loss) are studied. These results revealed that TiO2 NPs create inter-bands between valence and conduction bands. The addition of TiO2 NPs to the PS/PVC blend improves the electrical conductivity of the PS/PVC blend due to charge carrier buildup and increased polymeric chain segmental mobility inside the polymeric matrices.

Ultra-selective molecular-sieving gas separation membranes enabled by multi-covalent-crosslinking of microporous polymer blends.

Abstract: High-performance membranes exceeding the conventional permeability-selectivity upper bound are attractive for advanced gas separations. In the context microporous polymers have gained increasing attention owing to their exceptional permeability, which, however, demonstrate a moderate selectivity unfavorable for separating similarly sized gas mixtures. Here we report an approach to designing polymeric molecular sieve membranes via multi-covalent-crosslinking of blended bromomethyl polymer of intrinsic microporosity and Troger’s base, enabling simultaneously high permeability and selectivity. Ultra-selective gas separation is achieved via adjusting reaction temperature, reaction time and the oxygen concentration with occurrences of polymer chain scission, rearrangement and thermal oxidative crosslinking reaction. Upon a thermal treatment at 300 °C for 5 h, membranes exhibit an O2/N2, CO2/CH4 and H2/CH4 selectivity as high as 11.1, 154.5 and 813.6, respectively, transcending the state-of-art upper bounds. The design strategy represents a generalizable approach to creating molecular-sieving polymer membranes with enormous potentials for high-performance separation processes. Microporous polymers become increasingly attractive as materials for the fabrication of permeable and selective gas separation membranes but separation performance is often limited by broad pore size distribution. Here, the authors design a porous polymer membrane via multi-crosslinking of miscible blends of microporous polymers enabling simultaneous high permeability and selectivity.

Embedding of 50%PVA/50%PVP blend with Sn0.75M0.25S2, (M = Y, Fe, Cr, V); structural and optical study

Abstract: Blended polymers, polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP), embedded with nano Sn0.75M0.25S2, (M = Y, Fe, Cr, V) were prepared using thermolysis and casting procedures. Rietveld refinement was used to investigate the structure and microstructure of the powder nano-filler Sn0.75M0.25S2, (M = Y, Fe, Cr, V). SEM images of 50%PVA/50%PVP doped with the powder samples revealed a homogeneous distribution of the nano-filler over the polymer blend. X-ray diffraction patterns exhibited small degree of crystallinity coupled with a diffuse scattering referring to an amorphous phase. Transmission FTIR spectra confirmed the incorporation of nano-filler into the blend matrix. The effect of nano-filler on the transmittance, optical absorption coefficient, extinction coefficient, refractive index, the optical bandgap, Urbach energy, steepness parameter, optical conductivity, the real and imaginary parts of the dielectric constant of the 50%PVA/50%PVP blend was studied using UV–vis spectrophotometry technique. Fluorescence (FL) spectra analysis revealed that the emitted color and Fl intensity depended on the kind of nano-filler and excitation wavelength.

Structural, dielectric, and magnetic studies based on MWCNTs/NiFe2O4/ZnO nanoparticles dispersed in polymer PVA/PEO for electromagnetic applications

Abstract: The hydrothermal and the co-precipitation methods were used for the formation of new multifunctional MWCNTs/NiFe2O4/ZnO (MNFZ) hybrid nanostructures. The MNFZ hybrid nanostructure formation was asserted by characterizing it via the X-ray diffraction (XRD) analysis and TEM. Then, the casting technique was used for preparing the MNFZ nanoparticle-doped Poly (vinyl alcohol) (PVA) and poly (ethylene oxide) (PEO) by various concentrations of MNFZ NPs as nanofiller. All polymer blend and nanocomposite films are shown by XRD studies to have a semicrystalline nature with a reduced degree of semi-crystallinity with the dopant. The infrared absorption band shift and the intensity change indicate the interaction or complexation between the blend and nanofiller is confirmed by FTIR studies. The volume percentage variation of the nanoparticles and the ferromagnetic response variation of the nanocomposite were in consistency. The dielectric characteristics and ac conductivity of the film polymer blend were higher upon adding the nanofiller because the charge carrier number was higher. Such features of MNFZ-doped PVA/PEO films prove their appropriateness as materials for electromagnetic applications.