Increase In Surface Energy Research Articles

Fabrication and Characterization of Piezoelectric Polymer Composites and Cytocompatibility with Mesenchymal Stem Cells.

Piezoelectric materials are promising for biomedical applications because they can provide mechanical or electrical stimulations via converse or direct piezoelectric effects. The stimulations have been proven to be beneficial for cell proliferation and tissue regeneration. Recent reports showed that doping different contents of reduced graphene oxide (rGO) or polyaniline (PANi) into biodegradable polyhydroxybutyrate (PHB) enhanced their piezoelectric response, showing potential for biomedical applications. In this study, we aim to determine the correlation between physiochemical properties and the in vitro cell response to the PHB-based composite scaffolds with rGO or PANi. Specifically, we characterized the surface morphology, wetting behavior, electrochemical impedance, and piezoelectric properties of the composites and controls. The addition of rGO and PANi resulted in decreased fiber diameters and hydrophobicity of PHB. The increased surface energy of PHB after doping nanofillers led to a reduced water contact angle (WCA) from 101.84 ± 2.18° (for PHB) to 88.43 ± 0.83° after the addition of 3 wt % PANi, whereas doping 1 wt % rGO decreased the WCA value to 92.56 ± 2.43°. Meanwhile, doping 0.2 wt % rGO into PHB improved the piezoelectric properties compared to the PHB control and other composites. Adding up to 1 wt % rGO or 3 wt % PANi nanofillers in PHB did not affect the adhesion densities of bone marrow-derived mesenchymal stem cells (BMSCs) on the scaffolds. The aspect ratios of attached BMSCs on the composite scaffolds increased compared to the PHB control. The study indicated that the PHB-based composites are promising for potential applications such as regenerative medicine, tissue stimulation, and bio-sensing, which should be further studied.

Kirkendall effect Strengthened-Superhydrophilic/superaerophobic Co-Ni3N/NF heterostructure as electrode catalyst for High-current hydrogen production

The development of efficient electrocatalysts for large-scale water electrolysis is crucial and challenging. Research efforts towards interface engineering and electronic structure modulation can be leveraged to enhance the electrochemical performance of the developed catalysts. In this work, a surface-engineered Co-Ni3N/NF heterostructure electrode was prepared based on Kirkendall effect for high-current water electrolysis. In the experiments, the textural feature and intrinsic activity of the Co-Ni3N/NF heterostructure were tuned through cobalt-doping and the creation of structural defects. As a result, the increased surface energy endowed Co-Ni3N/NF heterostructure with superhydrophilic and superaerophobic properties. Meanwhile, the contact area of the gas–liquid-solid three phases was optimized. With a large underwater bubble contact angle (CA) of 169°, the electrolyte solution can infiltrate the Co-Ni3N/NF electrode within 150 ms. Sequentially, the generated gas bubbles were able to detach at high frequency, which ensured the rapid mass exchange. The performance tests showed that the optimal Co-Ni3N/NF electrode sample reached current densities of 100 mA cm−2 and 500 mA cm−2 at the overpotentials of 98 mV and 123 mV, respectively. Benefiting from the reduction of hydrogen embrittlement, the HER performance of the prepared Co-Ni3N/NF electrode sample decreased slightly after 100 h durability test, but the overall structure remained well. Those results allowed us to conclude that the prepared Co-Ni3N/NF electrocatalyst holds the promises for large-scale water electrolysis in industries. More specifically, this work provided a new perspective that the efficiency of electrocatalysts for large-scale water electrolysis can be enhanced by constructing a heterostructure with good wettability and gas repellency.

Roles of aqueous nonsolvents influencing the dynamic stability of poly-(n-butyl methacrylate) thin films at biologically relevant temperatures.

Poly-(n-butyl methacrylate) (PnBMA) is an important polymer in biomedical applications. Here we study the stability of PnBMA thin films prepared on top of slippery silicon substrates and exposed to nonsolvent aqueous incubation media like water and phosphate-buffered saline (PBS) at temperatures relevant to biological applications (37 °C, 25 °C and 4 °C). Dewetting hole growth experiments allowed us to probe the instability in PnBMA films upon incubation followed by thermal annealing. From the early stage of dewetting hole growth dynamics, we inferred that the stability of the thin PnBMA films decreases as a function of the duration and temperature of incubation, even though the films were found not to readily dewet at room temperature after incubation. It is also observed that water incubation makes films more unstable than incubation in PBS. We explained our observations as a combined effect of (i) an increase in surface energy of the PnBMA film due to incubation, (ii) an increased destabilizing effect due to the dominant polar interactions between the incubation medium and the PnBMA film and (iii) the plasticization effect of PnBMA films by the incubation media. Plasticization resulted in a decrease in the modulus of PnBMA thin films as a function of incubation time. The viscosity of PnBMA films upon incubation was found to be coupled to the decreasing modulus. Thus we infer that incubation in common aqueous nonsolvents can detrimentally affect the stability of polymers limiting their specific usages through a complex interplay of multiple molecular level phenomena.

Carbon nitride based materials: more than just a support for single-atom catalysis.

Recently, the missing link between homogeneous and heterogeneous catalysis has been found and it was named single-atom catalysis (SAC). However, the SAC field still faces important challenges, one of which is controlling the bonding/coordination between the single atoms and the support in order to compensate for the increase in surface energy when the particle size is reduced due to atomic dispersion. Excellent candidates to meet this requirement are carbon nitride (CN)-based materials. Metal atoms can be firmly trapped in nitrogen-rich coordination sites in CN materials, which makes them a unique class of hosts for preparing single-atom catalysts (SACs). As one of the most promising two-dimensional supports to stabilize isolated metal atoms, CN materials have been increasingly employed for preparing SACs. Herein, we will cover the most recent advances in single-atoms supported by CN materials. In this review, the most important characterization techniques and the challenges faced in this topic will be discussed, and the commonly employed synthetic methods will be delineated for different CN materials. Finally, the catalytic performance of SACs based on carbon nitrides will be reviewed with a special focus on their photocatalytic applications. In particular, we will prove CN as a non-innocent support. The relationship between single-atoms and carbon nitride supports is two-way, where the single-atoms can change the electronic properties of the CN support, while the electronic features of the CN matrix can tune the catalytic activity of the single sites in photocatalytic reactions. Finally, we highlight the frontiers in the field, including analytical method development, truly controlled synthetic methods, allowing the fine control of loading and multi-element synthesis, and how understanding the two-way exchange behind single-atoms and CN supports can push this topic to the next level.

Understanding the Daytime and Nighttime Impacts of Dust Aerosols on Surface Energy and Meteorological Fields in Northwest China

AbstractDust aerosols pose non‐negligible impacts on regional and global climate, particularly over northwest China (NWC), where dust events frequently occur. Here, six dust events with different intensities occurred from 2014 to 2019 in NWC were simulated by the Weather Research and Forecasting model coupled to Chemistry (WRF‐Chem) to quantitatively evaluate the contributions of dust aerosols to radiation fluxes, surface energy, and meteorology, with specific consideration to the distinctions between daytime and nighttime. The results show that the contributions of dust aerosols to surface energy and meteorology were significantly affected by dust concentrations and dust layer heights and exhibited diurnal variation. In the case with high dust concentration and low dust layer height, dust aerosols increased the surface energy during the nighttime but decreased in the daytime, and the increase was much greater than the decrease. As a result, dust aerosols increase surface energy (0.06 W/m2 in the dust source region; 0.13 W/m2 in the dust affected region (DAR)) and surface temperature (0.0088°C in the DSR; 0.0781°C in the DAR) and decrease surface relative humidity (−0.053% in the DSR; −0.205% in the DAR) throughout the whole day. In contrast, dust causes opposite impacts on surface meteorology throughout the whole day due to the nighttime warming effect from the dust events with low dust concentration and high dust layer height is lesser than the daytime cooling effect. The study provides scientific insights for improving our understanding of dust aerosols‐regional meteorology interaction.

Effect of glaze and chlorhexidine on physical and mechanical properties of bis-acryl resin: An in situ study.

Temporary prosthesis protects the oral tissues, in addition to providing aesthetic look and masticatory function until a definitive prosthesis is manufactured. To evaluate the effect of glaze and 0.12% chlorhexidine (CHX) on the physical and mechanical properties of bis-acryl, and to evaluate the antimicrobial efficacy of CHX. Eighty specimens of bis-acryl resin were made. Over 40 of them the glaze was applied. One specimen with and 1 specimen without glaze were placed in niches of an appliance manufactured for each patient. Each of the 20 volunteers received 2 devices. Initially, the volunteers used one device and treated it with sucrose for 7 days (control), and later they used the other device and treated it with sucrose and CHX for 7 days (test). Color, microhardness, roughness, surface energy, and insoluble extracellular polysaccharides (EPS) tests were performed. All results were submitted to the Tukey's test, with the exception of the EPS results, which were submitted to the Student's t test. The ΔE00 of the unglazed control group was significantly higher than that of the unglazed test group. In all groups, a significant decrease in microhardness occurred over time. At both times, the glaze significantly increased the microhardness of the specimens (in all the glazed groups). At the final time, the test glaze group showed significantly higher microhardness compared with the control glaze group. Roughness in the groups without glaze increased significantly with CHX treatment over time. At both times, the glaze generated a significant reduction in roughness in the control and test groups. There was a significant reduction in surface energy over time in all groups. In most comparisons, the glazed groups showed significantly higher surface energy values compared with the unglazed control group. At the final time point, the unglazed test group showed a significantly higher surface energy value than the unglazed control group; and the glazed test group showed a significantly higher surface energy value compared with the glazed control group. The resins that received CHX had a significantly lower amount of biofilm. Color values were clinically acceptable in all tested groups. At both time points, the roughness values were clinically acceptable only in the glazed groups. Glaze increased the microhardness of the specimens. Microhardness and surface energy were reduced over time in all groups. Chlorhexidine can help prevent microhardness degradation. Glaze and CHX can increase surface energy. Chlorhexidine reduced the amount of bacterial biofilm.

How macrostructures enhance droplet coalescence jumping: A mechanism study

Macrostructures exhibit excellent performance in coalescence-induced droplet jumping enhancement. Previous velocity prediction models were mainly established for flat plain surface, which usually set up the balance relationship between excess surface energy, kinetic energy and dissipation. But these models are no longer appropriate in macrostructure cases due to great variation of oscillational kinetic energy and gravitational potential energy caused by textures. In this work, coalescence-induced droplet jumping on macrostructures was investigated numerically on flat, sidewall, string, ridge and egg shape substrates. An energy conversion model based on energy efficiency rather than energy balance was established for departure velocity by proposing three sub-efficiencies to evaluate jumping enhancement. In this model, oscillational kinetic energy was distinguished from dissipation, gravitational potential energy induced by macrostructures were considered, and the real droplet morphology were used to calculate surface energy. By dividing the whole droplet jumping process into merge and contact stage, the influence of macrostructures on duration of each stage was closely connected to the macrostructure effects on dissipation and kinetic energy conversion. Pressure and velocity distributions near the macrostructure were also discussed to further explore the mechanism for droplet jumping enhancement. Further, the significant increase of initial surface energy for egg case points out a possible new approach to enhance jumping velocity. This model helps us understand the determinants of jumping enhancement with macrostructures and it also applies to flat plain.

Homogeneous and aligned ZnO nanorods@Jute fibers for enhanced mechanical/microwave absorbing performance and thermal stability

With the needs of lightweight and sustainable development, the structure-function integration of natural fibers through multiscale surface modification has attracted much attention. Jute fibers (JFs) stand out from other natural alternatives because of their unique hierarchical structure, lower production cost and better mechanical properties. In this work, a facile and effective strategy for preparing ZnO nanorods (NRs) @JFs was proposed by an in-situ method. The introduction of ZnO NRs not only reinforces the fiber, but also endows additional functionalities. The components and morphologies of ZnO@JFs were characterized. The structurally optimized ZnO@JFs exhibit a significant increase in surface energy, tensile strength, elongation at break, thermal stability with 150.0%, 16.8%, 8.5%, 216.9%, respectively, as well as remarkable enhancement in microwave absorption with 40.0%. These homogeneous and aligned ZnO NRs@JFs that integrate reinforced structure and additional functions have great application potential in the fields of automotive industry, building construction and aerospace.

Application of Graphene Oxide as a Biomaterial for the Development of Large-Area Cell Culture Vessels

In this study, graphene oxide (GO) was coated on the surface of a large-area polystyrene film using spray coating. To analyze the possibility of developing a large-area cell culture vessel from this material, the mechanical properties of the coated surface as well as the cell compatibility and cell proliferation in the vessel were evaluated. Step measurements confirmed a curve of 100 nm or larger on the cell culture vessel surface. The surface was composed of GO (as determined from Raman spectroscopy) and its measured transmittance was ~90% or higher. The coated surface was rendered hydrophilic with an increase in surface energy. Although the cells hardly grew on the general polystyrene film, they attached and proliferated on the polystyrene film coated with GO. Zero cytotoxicity was reported, particularly in the sample that was spray-coated three times at 93.75 mm/s. Note that the cell viability was 1.43 times higher than that in the conventional cell culture vessel. Economic and efficient large-area cell culture vessels can be developed if the GO coating establishes an appropriate surface roughness and surface energy.

Polyether Ether Ketone Coated with Ultra-Thin Films of Titanium Oxide and Zirconium Oxide Fabricated by DC Magnetron Sputtering for Biomedical Application.

Recently, polyether ether ketone has raised increasing interest in research and industry as an alternative material for bone implants. This polymer also has some shortcomings, as it is bioinert and its surface is relatively hydrophobic, causing poor cell adhesion and therefore slow integration with bone tissue. In order to improve biocompatibility, the surface of polyether ether ketone-based implants should be modified. Therefore, polished disc-shaped polyether ether ketone samples were surface-modified by direct current magnetron sputtering with ultrathin titanium and zirconium coatings (thickness < 100 nm). The investigation results show a uniform distribution of both types of coatings on the sample surfaces, where the coatings mostly consist of titanium dioxide and zirconium dioxide. Differential scanning calorimetry revealed that the crystalline structure of the polyether ether ketone substrates was not changed by the coating deposition. Both coatings are amorphous, as shown by X-ray diffraction investigations. The roughness of both coating types increases with increasing coating thickness, which is beneficial for cell colonization. The coatings presented and investigated in this study improve wettability, increasing surface energies, in particular the polar component of the surface energies, which, in turn, are important for cell adhesion.

Triboelectric Generator Based on Oriented Self-Assembled Peptide Microbelts.

Along with piezoelectric nanogenerators, triboelectric nanogenerators (TENGs) collecting energy from mechanical vibrations proved to be simple, low-cost, and efficient sources of electricity for various applications. In view of possible biomedical applications, the search for TENGs made of biomolecular and biocompatible materials is demanding. Diphenylalanine (FF) microstructures are promising for these applications due to their unique characteristics and ability to form various morphologies (microribbons, spherical vesicles, fibrils, micro- and nanotubes, nanorods, etc.). In this work, we developed a contact-separate mode TENG based on arrays of oriented FF microbelts deposited by dip-coating technique and studied their performance under various temperature treatments. We show that these TENGs outperform piezoelectric nanogenerators based on FF microbelts in terms of short-circuit current (ISC), open-circuit voltage (VOC), and output power. It was found that bound water captured in FF nanochannels mainly affects VOC, whereas mobile water increases ISC. We also found that the cyclization of FF molecules increases the performance of TENG likely due to an increase in surface energy and surface flattening.

Impact of curvature-induced Dzyaloshinskii–Moriya interaction on magnetic vortex texture in spherical caps

The geometric curvature of nanoscale magnetic shells brings about curvature-induced anisotropy and Dzyaloshinskii–Moriya interaction (DMI). Here, we derive equations to describe the profile of the magnetic vortex state in a spherical cap. We demonstrate that the azimuthal component of magnetization acquires a finite tilt at the edge of the cap, which results in the increase of the magnetic surface energy. This is different compared to the case of a closed spherical shell, where symmetry of the texture does not allow any tilt of magnetization at the equator of the sphere. Furthermore, we analyze the size of the vortex core in a spherical cap and show that the presence of the curvature-induced DMI leads to the increase of the core size independent of the product of the circulation and polarity of the vortex. This is in contrast to the case of planar disks with intrinsic DMI, where the preferred direction of circulation as well as the decrease or increase of the size of vortex core is determined by the sign of the product of the circulation and polarity with respect to the sign of the constant of the intrinsic DMI.

Multifunctional Characteristics of Carbon Fibers Modified with Imidazolium Ionic Liquids.

A multifunctional designing approach is of great importance for advanced composite applications. This study assessed the use of ionic liquids (ILs) to modify the surface of carbon fiber (CF) and impart multifunctional characteristics to it. For that, ethanolic solutions of different ILs, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium chloride and 1-(2-hydroxyethyl)-3-methylimidazolium chloride, at different concentrations, were used to treat the CF. Fourier-transform infrared spectroscopy confirmed the presence of IL on the CF surface. The contact angle for 1% w/v IL-treated CF and DGEBA epoxy decreased by up to 35%, corresponding to an increase in surface energy of fiber, accompanied by an increase of 91% in interfacial shear strength. These enhancements were achieved with the hydroxy-functionalized IL, showing the tunability of CF properties through the N-imidazolium substituent. An increase in crystallite size along the basal plane was also found due to the ordering of the graphitic structure on the surface. Moreover, there was a decrease in electrical resistivity of 77%. In all, the imidazolium ILs were considered a promising approach to induce multifunctional characteristics, namely enhanced interfacial strength and electrical conductivity, to unsized CF, which can also be beneficial for recycled fibers without deteriorating their inherent surface properties.

Effects of solid–liquid interaction and mixture concentration on wettability of nano-droplets: Molecular dynamics simulations

The wetting of droplets plays a critical role in engineering applications. Intensive study on nano-droplets is of great significance in revealing the wetting characteristics of droplets. The wetting behavior of ethanol/water mixture nano-droplets on a smooth substrate was investigated through molecular dynamics simulation in this paper. Five nano-droplets of the ethanol/water mixture with different mass fractions placed on a copper surface with different surface energies were simulated to equilibrium at 298.15 K. The contract angle, wetting limit (the minimum and the maximum surface tension of droplets make the surface completely wetted or completely non-wetted by the droplet), and density distribution at the solid–liquid interface of the nano-droplet were analyzed. The effects of ethanol concentration and solid–liquid interaction (corresponding to the droplet’s surface tension and the substrate’s surface energy, respectively) on droplet wettability were intensely discussed. Results revealed that the contact angle of nano-droplets decreased with the increase in ethanol concentration and the interaction between droplets and the substrate. In addition, the critical and ultimate surface tension increased with the increase in the substrate surface energy. The peak density values of the droplets were proportional to the interaction between the droplets and substrate and not related to the droplet concentration. The research also indicated that solid substrates with different surface energies and droplets with various components affected the contact angle of droplets in different ways: the former not only increased the surface tension of droplets at the solid–liquid interface but also increased the separation energy of solids and droplets, while the latter only had a great influence on the surface tension of droplets at the solid–liquid interface.

Atomic Imaging and Thermally Induced Dynamic Structural Evolution of Two-Dimensional Cr2S3.

In this study, facile salt-assisted chemical vapor deposition (CVD) was used to synthesize ultrathin non-van der Waals chromium sulfide (Cr2S3) with a thickness of ∼1.9 nm. The structural transformation of as-grown Cr2S3 was studied using advanced in situ heating techniques combined with transmission electron microscopy (TEM). Two-dimensional (2D) and quasi-one-dimensional (1D) samples were fabricated to investigate the connection between specific planes and the dynamic behavior of the structural variation. The rearrangement of atoms during the phase transition was driven by the loss of sulfur atoms at elevated temperatures, resulting in increased free energy. A decrease in the ratio of the (001) plane led to an overall increase in surface energy, thus lowering the critical phase transition temperature. Our study provides detailed insight into the mechanism of structural transformation and the critical factors governing transition temperature, thus paving the way for future studies on intriguing Cr-S compounds.

Polyvinylidene fluoride/polysulfone/air plasma defected hexagonal boron nitride emerging nano blends for electrostatic dissipation

AbstractIn the present era electrostatic dissipation (ESD) property is crucial for packaged electronic device to protect from humidity over long duration. It was important to control the ESD for better integrated packaged electronic gadgets. Polymer blends and composites were modified with nano fillers as a promising area for ESD applications. In the present investigation, polyvinylidene fluoride (PVDF)/polysulfone (PSF) was modified by untreated (UT) and air plasma treated (PT) hexagonal boron nitride (h‐BN) by solution dispersion method. Spherulitic morphology of nano blends was foreseen through scanning electron microscopy. Surface topography was investigated by atomic force microscopy. Surface roughness was decreased due to plasma exposure. Phonon vibrations and Raman active mode of nano blends were confirmed by Raman spectroscopy mutually supporting ESD phenomenon. Increased electrical conductivity and semicircular impedance pattern of modified blends reveals an excellent ESD property disclosed by impedance spectroscopy. Moderate increased surface energy and decreased relative contact angle of modified blends may be due to the incorporation of polar groups during plasma exposure was confirmed by surface goniometer. Mechanical properties of nano blends were evaluated by universal testing machine. Increased 10–27% tensile strength and 34–55% Young's modulus of plasma treated admix composition. Softness of polymer nano blends was increased (20%) due to excellent interaction of filler and polymer host system were tested by Shore “A” durometer. Increased glass transition temperature (Tg = 16 and 30°C as function of treatment time) in view of thermal stability of modified nano blends were analyzed by thermogravimetric technique. Hence the PT h‐BN dispersed PVDF/PSF emerging polymer nano blends would be a choice for the new development for electrostatic dissipation applications.

Radiation damage behavior and mechanism in RAFM steel: Orientation effect

The experiments and molecular dynamics simulations were performed to obtain the orientation effect on the behavior and mechanism of irradiation resistance in the RAFM steel. The irradiation surface morphologies, Frenkel defects, and clusters analysis reveal that the irradiation resistance of different orientations is as follows, (110) > (100) > (112) > (233) > (111) orientation. Additionally, the (233) orientation is easier to form vacancy defect clusters, while the (111) orientation is easy to form a large number of small clusters, which are determined by the clustering rates of interstitial atomic and vacancy clusters. Surface energy, atomic arrangement density, and atomic bonds play a significant role in the orientation effect on the radiation damage resistance. The radiation damage resistance of different orientations increased with the increase of atomic arrangement density and atomic bonding strength, while it decreased with the increase of surface energy.

Nanostructured hafnium-doped strontium oxide film for homeotropic/homogeneous convertible liquid crystal alignment depending on the curing temperature

ABSTRACT A hafnium strontium oxide (HfSrO) liquid crystal (LC) alignment film was efficiently created through brush coating, and its ability to change the LC alignment direction was confirmed. A brush was applied to HfSrO sol coated on an indium-tin oxide substrate, after which the coating was solidified at various curing temperatures. It was confirmed that a directional micro/nanostructure was formed above 280°C due to the shear stresses caused by the movement of the brush hairs. Surface chemical changes were analyzed by using X-ray photoelectron spectroscopy and contact angle measurements. As the curing temperature increased, the prevalence of oxygen bonds increased and the contact angle decreased, thereby increasing the surface energy. The anisotropic boundary of the microgrooves and the van der Waals forces due to an increase in surface energy changed the alignment direction of LC molecules from vertical to horizontal, as verified through polarized optical microscopy and pretilt angle measurements. Thus, the efficiency of the brush-coating method, which dramatically simplifies the LC alignment film process, was confirmed. The homeotropic/homogeneous LC alignment property of the HfSrO film produced through brush coating depending on the curing temperature provides an innovative approach for LC alignment.

Characteristics and radiolysis behavior of polyvinylchloride under accelerated proton and γ-irradiation

The effect of high energy protons and γ-irradiation on the structural properties, surface-energies, and toxicological properties of polyvinyl chloride (PVC) were studied due to the role PVC products play in many technologies including the nuclear industry. Accelerated 1–4 MeV protons impacting on PVC in vacuum lead to the formation of polyenyl radicals as shown by EPR and to an increase in free surface energy due to functionalization of the surface of the irradiated polymer. γ-irradiation leads to the formation of unsaturated bonds, carbonyl and hydroxyl groups as shown by IR and to the release of HCl. Correlated molecular orbital theory calculations of reaction thermodynamics were used to aid in the development of a mechanism in the absence of oxygen. The formation and accumulation of chromophores and auxochromic groups during γ-radiolysis of PVC leads to a gradual change of the initial white color of the polymer to yellow and then to brown and black with high sensitivity. A mixture of powdered PVC and silicate glue was used to determine the profile of a 60Co γ-radiation beam on targets with a complex relief. γ-irradiated polymer does not have a local irritating effect due to a single application to the skin of mice in an adhesive mixture at a concentration of up to 5000 mg/kg. γ-radiolysis of PVC powder in air with a dose of up to 1400 kGy does not affect its acute toxicity when administered intragastrically to BDF1 mice. PVC and its γ-irradiated analogs are non-toxic at doses ≤5000 mg/kg.

High‐Performance Inkjet‐Printed Blue QLED Enabled by Crosslinked and Intertwined Hole Transport Layer

AbstractA novel crosslinkable 4,4′‐(9,9‐dimethyl‐9H‐fluorene‐2,7‐diyl)bis(N‐phenyl‐N‐(4‐vinylphenyl)aniline) (FLTA‐V) based on TFB repeat unit is designed and synthesized. A blended film with optimized 2:1 weight ratio of TFB and FLTA‐V is employed to act as the effective hole transport layer (HTL) for quantum dot light‐emitting diode (QLED). The resulted HTL is crosslinked and exhibits excellent solvent‐resistant property without any initiators. It also forms a robust network structure and the TFB molecules are intertwined and imprisoned in the network. The HTL then becomes denser, which enhances both intermolecular interactions and π‐π stacking to further promote efficient charge transportation. Moreover, the closeness of highest occupied molecular orbital levels between TFB (−5.4 eV) and FLTA‐V (−5.6 eV) is beneficial for hole injection from HTL to QD layer. The increased surface energy of blended HTL ensures better electrical contact between HTL and QDs, which reduces the leakage current of the device. The combination of these favorable factors has led to the fabricated blue QLED showing a remarkable enhancement of external quantum efficiency (EQE) from 7.23% for the control TFB‐based device to 10.20% for blended HTL‐based device. In addition, a maximum of 6.82% of EQE for inkjet‐printed blue QLED has been achieved, which is the best‐reported high‐efficiency inkjet‐printed blue QLED to date.