Showing papers on "Thermal stability published in 2017"
TL;DR: This study indicates that the LLZTO modifying PVDF membrane is a promising electrolyte used for all-solid-state lithium batteries.
Abstract: Easy processing and flexibility of polymer electrolytes make them very promising in developing all-solid-state lithium batteries. However, their low room-temperature conductivity and poor mechanical and thermal properties still hinder their applications. Here, we use Li6.75La3Zr1.75Ta0.25O12 (LLZTO) ceramics to trigger structural modification of poly(vinylidene fluoride) (PVDF) polymer electrolyte. By combining experiments and first-principle calculations, we find that La atom of LLZTO could complex with the N atom and C═O group of solvent molecules such as N,N-dimethylformamide along with electrons enriching at the N atom, which behaves like a Lewis base and induces the chemical dehydrofluorination of the PVDF skeleton. Partially modified PVDF chains activate the interactions between the PVDF matrix, lithium salt, and LLZTO fillers, hence leading to significantly improved performance of the flexible electrolyte membrane (e.g., a high ionic conductivity of about 5 × 10–4 S cm–1 at 25 °C, high mechanical s...
617 citations
TL;DR: A new strategy is reported for the generation of single Pt atoms and Pt clusters with exceptionally high thermal stability, formed within purely siliceous MCM-22 during the growth of a two-dimensional zeolite into three dimensions.
Abstract: Single metal atoms and metal clusters have attracted much attention thanks to their advantageous capabilities as heterogeneous catalysts. However, the generation of stable single atoms and clusters on a solid support is still challenging. Herein, we report a new strategy for the generation of single Pt atoms and Pt clusters with exceptionally high thermal stability, formed within purely siliceous MCM-22 during the growth of a two-dimensional zeolite into three dimensions. These subnanometric Pt species are stabilized by MCM-22, even after treatment in air up to 540 °C. Furthermore, these stable Pt species confined within internal framework cavities show size-selective catalysis for the hydrogenation of alkenes. High-temperature oxidation–reduction treatments result in the growth of encapsulated Pt species to small nanoparticles in the approximate size range of 1 to 2 nm. The stability and catalytic activity of encapsulated Pt species is also reflected in the dehydrogenation of propane to propylene. Encapsulation of single-atom and particulate gold within growing zeolite frameworks generates active catalysts with exceptionally high thermal stability.
435 citations
TL;DR: In this article, the authors focus on the preparation, characterization, and improvement of thermal conductivity using CNTs as well as determination of TES properties of expanded perlite (ExP)/ n -eicosane (C20) composite as a novel type of form-stable composite PCM (F-SCPCM).
424 citations
TL;DR: In this article, the thermal degradation process of the inverted structured PSCs induced by the silver electrode is thoroughly investigated, and direct evidences provide in-depth understanding of the effect of thermal stress on the devices.
Abstract: Perovskite solar cells (PSCs) have recently demonstrated high efficiencies of over 22%, but the thermal stability is still a major challenge for commercialization. In this work, the thermal degradation process of the inverted structured PSCs induced by the silver electrode is thoroughly investigated. Elemental depth profiles indicate that iodide and methylammonium ions diffuse through the electron-trasnporting layer and accumulate at the Ag inner surface. The driving force of forming AgI then facilitates the ions extraction. Variations on the morphology and current mapping of the MAPbI3 thin films upon thermal treatment reveal that the loss of ions occurs at the grain boundaries and leads to the reconstruction of grain domains. Consequently, the deteriorated MAPbI3 thin film, the poor electron extraction, and the generation of AgI barrier result in the degradation of efficiencies. These direct evidences provide in-depth understanding of the effect of thermal stress on the devices, offering both experimental support and theoretical guidance for the improvement on the thermal stability of the inverted PSCs.
262 citations
TL;DR: This work developed a simple strategy to synthesize alkyl phosphate (TDPA) coated CsPbBr3 QDs by using 1-tetradecylphosphonic acid both as the ligand for the CspbBr 3 QDs and as the precursor for the formation of alkyL phosphate.
Abstract: Inorganic halide perovskite quantum dots (QDs) suffer from problems related to poor water stability and poor thermal stability. Here we developed a simple strategy to synthesize alkyl phosphate (TDPA) coated CsPbBr3 QDs by using 1-tetradecylphosphonic acid both as the ligand for the CsPbBr3 QDs and as the precursor for the formation of alkyl phosphate. These QDs not only retain a high photoluminescence quantum yield (PLQY, 68%) and narrow band emission (FHWM ∼ 22 nm) but also exhibit high stability against water and heat. The relative PL intensity of the QDs was maintained at 75% or 59% after being dispersed in water for 5 h or heated to 375 K (100 °C), respectively. Finally, white light-emitting diodes (WLEDs) with a high luminous efficiency of 63 lm W−1 and a wide color gamut (122% of NTSC) were fabricated by using green-emitting CsPbBr3/TDPA QDs and red-emitting K2SiF6:Mn4+ phosphors as color converters. The luminous efficiency of the WLEDs remained at 90% after working under a relative humidity (RH) of 60% for 15 h, thereby showing promise for use as backlight devices in LCDs.
212 citations
TL;DR: An energetic compound, [2,2′-bi(1,3,4-oxadiazole)]-5,5′-dinitramide, is synthesized through a two-step reaction from commercially available reagents that exhibit good heat thermal stability and detonation properties.
Abstract: High-energy density materials represent a significant class of advanced materials and have been the focus of energetic materials community. The main challenge in this field is to design and synthesize energetic compounds with a highest possible density and a maximum possible chemical stability. Here we show an energetic compound, [2,2′-bi(1,3,4-oxadiazole)]-5,5′-dinitramide, is synthesized through a two-step reaction from commercially available reagents. It exhibits a surprisingly high density (1.99 g cm−3 at 298 K), poor solubility in water and most organic solvents, decent thermal stability, a positive heat of formation and excellent detonation properties. The solid-state structural features of the synthesized compound are also investigated via X-ray diffraction and several theoretical techniques. The energetic and sensitivity properties of the explosive compound are similar to those of 2, 4, 6, 8, 10, 12-(hexanitrohexaaza)cyclododecane (CL-20), and the developed compound shows a great promise for potential applications as a high-energy density material. High energy density materials are of interest, but density is the limiting factor for many organic compounds. Here the authors show the formation of a high density energetic compound from a two-step reaction between commercially available compounds that exhibit good heat thermal stability and detonation properties.
205 citations
TL;DR: In this article, the degradation pathway of methylammonium lead iodide microplates was investigated using in situ transmission electron microscopy to follow the thermal degradation process, and it was shown that under moderate heating at 85°C the crystalline structure shows a gradual evolution from tetragonal MAPbI3 to trigonal lead iodides layered with a fixed crystallographic direction.
194 citations
TL;DR: These nitrogen-doped carbon dots, which were prepared via the hydrothermal treatment of citric acid and tris(hydroxymethyl)methyl aminomethane, have a high QY of 75%, together with excellent thermal and photo stability and allow them to be used as invisible ink for loading important information and advanced anti-counterfeiting.
Abstract: High quantum yields (QY) and stable performances are prerequisites for implementing carbon dots in practical applications. In this study, we demonstrate that nitrogen-doped carbon dots (N-CDs), which were prepared via the hydrothermal treatment of citric acid (CA) and tris(hydroxymethyl)methyl aminomethane (Tris), have a high QY of 75%, together with excellent thermal and photo stability. These N-CDs deliver an excellent thermal stability performance over the temperature range of 25 °C to 95 °C, and even at a heating temperature of 90 °C for 360 min. Upon exposure to UV illumination with a radiant intensity of 20 mW cm-2, 96% fluorescence intensity is retained. This florescence stability performance is probably due to the chemical composition and steric effect of the nitrogen-doping agent. Furthermore, the remarkable optical properties of these N-CDs allow them to be used as invisible ink for loading important information and advanced anti-counterfeiting.
188 citations
TL;DR: Evaluated effects of inorganic acids on the production of BC nanocrystals (BCNCs) resulted in improved thermal stability without decreased crystallinity, and all BCNC suspensions exhibited zeta potential moduli greater than 30mV, indicating good colloidal stability.
188 citations
TL;DR: It is concluded that 0.75% CNFs loading is the minimal to enhance both thermal and dynamic mechanical properties of the epoxy composites and can be utilized for advance material applications where thermal stability along with renewability are prime requirements.
186 citations
TL;DR: In this paper, a surface coating of Li 3 PO 4 was applied to a Ni-rich LiNi 0.6 Co 0.2 O 2 (NCM) material to improve its thermal stability and electrochemical properties via a citric acid assisted sol-gel method.
TL;DR: A full recovery of photovoltaic performance was observed for the 85 °C-aged device after renewal with fresh spiro-MeOTAD, which implies that the thermal stability of perovskite solar cells depends on selective contacts.
Abstract: Thermal stability of CH3NH3PbI3 (MAPbI3)-based perovskite solar cells was investigated for normal structure including the mesoporous TiO2 layer and spiro-MeOTAD and the inverted structure with PCBM and NiO. MAPbI3 was found to be intrinsically stable from 85 °C to 120 °C in the absence of moisture. However, fast degradation was observed for the encapsulated device including spiro-MeOTAD upon thermal stress at 85 °C. Photoluminescence (PL) intensity and the time constant for charge separation increased with thermal exposure time, which is indicative of inhibition of charge separation from MAPbI3 into spiro-MeOTAD. A full recovery of photovoltaic performance was observed for the 85 °C-aged device after renewal with fresh spiro-MeOTAD, which clearly indicates that thermal instability of the normal structured device is mainly due to spiro-MeOTAD, and MAPbI3 is proved to be thermally stable. Spiro-MeOTAD with additives was crystallized at 85 °C due to a low glass transition temperature, and hole mobility was s...
TL;DR: The use of oligo ethylene glycol side chains is demonstrated to significantly improve the processability of the conjugated polymer p(g4 2T-T)-a polythiophene-in polar aprotic solvents, which facilitates coprocessing of dopant:polymer pairs from the same solution at room temperature.
Abstract: Molecular doping of organic semiconductors is critical for optimizing a range of optoelectronic devices such as field-effect transistors, solar cells, and thermoelectric generators. However, many dopant:polymer pairs suffer from poor solubility in common organic solvents, which leads to a suboptimal solid-state nanostructure and hence low electrical conductivity. A further drawback is the poor thermal stability through sublimation of the dopant. The use of oligo ethylene glycol side chains is demonstrated to significantly improve the processability of the conjugated polymer p(g4 2T-T)-a polythiophene-in polar aprotic solvents, which facilitates coprocessing of dopant:polymer pairs from the same solution at room temperature. The use of common molecular dopants such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is explored. Doping of p(g4 2T-T) with F4TCNQ results in an electrical conductivity of up to 100 S cm(-1) . Moreover, the increased compatibility of the polar dopant F4TCNQ with the oligo ethylene glycol functionalized polythiophene results in a high degree of thermal stability at up to 150 °C.
TL;DR: In this paper, the authors performed a detailed comparative theoretical study of Ni-rich layered oxides composed of Ni, Co, and Mn (NCMs) to advance their understanding of the cycling and thermal stability.
Abstract: Ni-rich lithiated layered oxides composed of Ni, Co, and Mn (NCMs) have shown tremendous promise as cathode materials in lithium-ion batteries (LIB) for electro-mobility applications. The capacity of these materials increases with nickel content, but there is a concomitant decrease in stability and stable operating voltage during cycling. Hence, it is of great importance to probe ways to increase the nickel content without sacrificing other important aspects. In this study, we performed a detailed comparative theoretical study of Ni-rich NCMs to advance our understanding of the cycling and thermal stability. On the basis of extensive analysis of density of states, magnetic structure, bond covalency, molecular orbital diagrams, Bader atomic charges, and oxygen binding energies, we draw several crucial conclusions: as the NCM materials become increasingly rich in Ni, (1) the amount of high-valence Ni-ions increases (i.e., N3+, Ni4+), (2) Ni4+ ions are readily reduced due to a low-lying LUMO, and hence can e...
TL;DR: In this article, the morphological, structural, chemical, and electrical characterization of WS2 thin films sensors were reported by drop casting a commercial solution of dispersed few-layer WS2 flakes on Si3N4 interdigitated substrates and annealing the films in air at 150°C, 250°C and 350°C.
Abstract: We report on the fabrication and on the morphological, structural, chemical and the electrical characterization of WS2 thin films sensors prepared by drop casting a commercial solution of dispersed few-layers WS2 flakes on Si3N4 interdigitated substrates and annealing the films in air at 150 °C, 250 °C and 350 °C. Thermal stability of WS2 in air at different annealing temperatures has been investigated by X-ray photoemission spectroscopy, scanning electron microscopy, X-ray diffraction and by simultaneous thermal analysis techniques. We found that WS2 is not stable in air and partially oxidizes to amorphous WO3 in the annealing temperature range 25 °C–150 °C. The oxidation of WS2 in air at 250 °C and 350 °C yields a composite crystalline WS2/WO3 hierarchical structure characterized by the presence of surface oxygen and sulphur vacancies. The contribution of each phase of the WS2/WO3 composite to the overall chemoresistive gas response utilizing H2 (1–10 ppm), NH3 (1–10 ppm) and NO2 (40 ppb–1 ppm) gases in dry air carrier is presented and discussed. WS2/WO3 composite films show excellent gas sensing properties to reducing (H2, NH3) as respect to oxidizing (NO2) gases at 150 °C operating temperature. In this work we found low detection limits of 1 ppm H2, 1 ppm NH3 and 100 ppm NO2 in dry air carrier, among the smallest so far ever reported for transition metal dichalcogenides. Furthermore, the sensor doesn’t show any cross sensitivity effects to both H2 and NH3 when exposed to water vapor. Outstanding reproducibility responses, by exposing the 150 °C annealed film to dynamic and cumulative gas pulses where obtained utilizing H2 gas.
TL;DR: In this article, the authors studied the thermal stability of CsxMA1−xPbI3 film and solar cells and found that Cs doping was vital to suppress trap states in the film since the trap states were related to halide deficiency during thermal annealing.
Abstract: Organic–inorganic hybrid perovskite solar cells are found to be sensitive to moisture, oxygen, UV light, light soaking, heat, electric field, etc. Among all these factors, thermal stability is one of the most challenging concerns affecting PSCs stability, since it is hard to avoid a temperature increase for solar cells during operation. In this work, we systematically studied the thermal stability of CsxMA1−xPbI3 film and solar cells. The introduction of Cs into the precursor solution would inevitably accelerate the film deposition rate, resulting in decreased grain size and more Cs atoms in the film than in the precursors. The study on thermal stability illustrated that perovskite degradation was highly related to the amount of oxygen in the air. A small amount of Cs doping (x = 0.09) was beneficial for better thermal stability. In addition, Cs doping also enhanced the device performance. The improvement of short-circuit currents came from the increased film thickness, which was due to the faster deposition rate for Cs doped samples. Besides, Cs doping was vital to suppress the trap states in the film since the trap states were related to halide deficiency during thermal annealing. At last, the final performance of Cs0.09MA0.91PbI3 reached 18.1%, with a JSC of 22.57 mA cm−2, VOC of 1.06 V, FF of 0.76.
TL;DR: In this article, a low temperature stable transition-film (STF) was used to prepare highly-dense and pinhole-free CsPbIBr 2 thin film with high crystalline quality, as well as a new structural design (FTO/NiO x/CsPbBr 2 /MoO x /Au) of all-inorganic perovskite solar cells toward long-term thermal stability.
TL;DR: In this paper, flexible and freestanding solid polymer electrolyte (SPE) films based on poly ethylene oxide (PEO) and poly (vinyl pyrrolidone) (PVP) complexed with LiNO3 have been developed by solution casting method.
TL;DR: In this article, an atomic layer deposition (ALD) approach was used to protect the surface of this cathode material powders from oxygen release during initial charge, which results in low initial coulombic efficiency, intense electrolyte oxidation and thermal instability.
TL;DR: In this article, the authors used copper phthalocyanine (CuPC) as a model hole-transporting material (HTM) for thermally stable perovskite solar cells.
Abstract: Successful commercialization of perovskite solar cells (PSCs) in the near future will require the fabrication of cells with high efficiency and long-term stability. Despite their good processability at low temperatures, the majority of organic conductors employed in the fabrication of high-efficiency PSCs [e.g., 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) and poly(triaryl amine) (PTAA)] have low thermal stability. In order to fabricate PSCs with excellent thermal stability, both the constituent material itself and the interface between the constituents must be thermally stable. In this work, we focused on copper phthalocyanine (CuPC) as a model hole-transporting material (HTM) for thermally stable PSCs since CuPC is known to possess excellent thermal stability and interfacial bonding properties. The CuPC-based PSCs recorded a high power conversion efficiency (PCE) of ∼18% and maintained 97% of their initial efficiency for more than 1000 h of thermal annealing at 85 °C. Moreover, the device was stable under thermal cycling tests (50 cycles, −45 to 85 °C). The high PCE and high thermal stability observed in the CuPC-PSCs were found to arise as a result of the strong interfacial and conformal coating present on the surface of the perovskite facets, located between CuPC and the perovskite layer. These results will provide an important future direction for the development of highly efficient and thermally stable PSCs.
TL;DR: In this article, a lithium-ion conducting gel polymer electrolyte (GPE) membrane containing PEO as a polymer host and liquid electrolyte has been prepared by a simple one-step procedure.
Abstract: A lithium-ion conducting gel polymer electrolyte (GPE) membrane containing PEO as a polymer host and liquid electrolyte has been prepared by a simple one-step procedure. The prepared electrolyte membrane exhibits a good ionic conductivity of 3.3 × 10−3 S cm−1 and high lithium transference number of 0.76 at room temperature. Meanwhile, the gel polymer electrolyte membrane shows very good thermal stability. A Li/GPE/LiFeO4 cell was fabricated to demonstrate the electrochemical performance of the GPE. The cell exhibits good cycling stability with a high capacity retention of 81% after 500 cycles and as good a rate performance as LiFeO4 tested in liquid electrolyte.
TL;DR: In this paper, a single-step method to produce the larger interplanar spacing 2D transition metal carbides and carbonitrides was demonstrated, and the optimal reaction conditions between Ti 3 AlC 2 and NH 4 HF 2 were systematically researched.
TL;DR: In this article, myristyl alcohol (MA)/metal foam composite phase change materials (CPCMs) were fabricated by vacuum melting infiltration and thermal properties including differential scanning calorimeter (DSC) test results and thermogravimetry analyzer results were investigated and recorded.
TL;DR: In this paper, Fourier transform infrared (FT-IR) and Ultraviolet/Visible (UV/Vis.) analyses were used to retrace the structural and optical changes with increasing Au content.
Abstract: Casting technique was used for preparation of polyethylene oxide (PEO)/polyvinyl pyrrolidone (PVP) (70/30 wt.%) films filled with different concentrations of gold nanoparticles (Au NPs). X-ray diffraction (XRD) pattern proved the semi-crystalline nature of the pristine and filled polymer blend. Fourier transform infrared (FT-IR) and Ultraviolet/Visible (UV/Vis.) analyses were used to retrace the structural and optical changes with increasing Au content. UV/Vis. analysis spectroscopy was utilized to calculate the optical properties such as optical energy gap E g , refractive index n and Urbach energy E u for blend/Au nanocomposite films. Scanning electron micrograph (SEM) suggested the dependence of morphological structure on filling level and the surface morphology changed from rough to smooth. Transmission electron microscope (TEM) micrographs showed that the size of Au NPs was increased with continuous filling in PEO/PVP. Thermogravimetric analysis (TGA) was performed to investigate the thermal stability for nanocomposite films.
TL;DR: LiNi0.9Co0.07Al0.03O2/KS6 has been assembled, delivering a high capacity of 210 mA h g−1 at 0.1C and excellent cycle stability as mentioned in this paper.
Abstract: The layered LiNi1−x−yCoxAlyO2 family with advantages of high capacity and low cost is considered as a promising cathode material for lithium-ion batteries (LIBs) for powering electric vehicles. However, such layered oxides still suffer from poor cycle stability and thermal instability during cycling. Herein, we report an easy coprecipitation synthesis of an Ni-rich microspherical Ni0.9Co0.07Al0.03(OH)2 precursor with uniform particle size and large BET specific surface area via employing AlO2− as the Al source. The uniform and dense LiNi0.9Co0.07Al0.03O2 microspheres with well-assembled nanoparticles and low degree of Ni2+/Li+ mixing are synthesized by optimizing the calcination conditions. As a cathode material for LIBs, LiNi0.9Co0.07Al0.03O2 delivers an appealing initial reversible capacity (236 mA h g−1 at 0.1C), good cyclic stability at various temperatures (e.g. capacity retention of 93.2% at 25 °C and 83.8% at 55 °C after 100 cycles at 1C), high rate capability (140 mA h g−1 at 10C), and excellent thermal stability (heat generation of 517.5 J g−1 at 4.3 V). Such superior electrochemical performance is mainly attributed to the combination of the high Ni component, layered structure with low degree of Ni2+/Li+ mixing, and uniform microspheres with homogeneous distribution of Ni, Co, and Al. Moreover, the full cell of LiNi0.9Co0.07Al0.03O2/KS6 has been assembled, delivering a high capacity of 210 mA h g−1 at 0.1C and excellent cycle stability.
TL;DR: In this paper, the surface of hexagonal nanometer boron nitride fillers (f-nBN) was functionalized with polyphenylene sulfide (pPS) to improve the thermal conductivities and dielectric properties.
Abstract: The proposed combining method of silane coupling agent of γ-aminopropyl triethoxy silane/aminopropyllsobutyl polyhedral oligomeric silsesquioxane (KH-560/NH2-POSS) was performed to functionalize the surface of hexagonal nanometer boron nitride fillers (f-nBN), aiming to fabricate the f-nBN/polyphenylene sulfide (f-nBN/PPS) nanocomposites with excellent thermal conductivities, outstanding thermal stabilities and optimal dielectric properties. The usage of f-nBN fillers was benifit for improving the thermally conductive coefficient (λ) and decreasing dielectric constant (e) values of the PPS nanocomposites. The f-nBN/PPS nanocomposite with 60 wt% f-BN fillers was an excellent dielectric nanocomposite with high λ & ideal e values and outstanding thermal stability, λ of 1.122 W/m K (increased by 400% compared to that of pristine PPS matrix), e of 3.99 and THeat-resistance index (THRI) beyond 275 °C, which holds potential for electronic packaging materials and ultra high voltage electrical apparatus.
TL;DR: In this paper, the thermal and physical properties of a composite reinforced with nanodiamonds and epitaxial boron nitride in an epoxy matrix were evaluated using 4,4′-methylene diphenyl diisocyanate as the coupling agent.
Abstract: This research focused on evaluating the thermal and physical properties of a composite reinforced with nanodiamonds and epitaxial boron nitride in an epoxy matrix. Nanodiamond-attached exfoliated hexagonal boron nitride nanoplates were fabricated using 4,4′-methylene diphenyl diisocyanate as the coupling agent. The morphology and structure of boron nitride (BN), exfoliated hexagonal BN nanoplates (EBN), and nanodiamond-attached EBN nanoplates (NDEBN) were determined. Epoxy composites were fabricated by in-situ polymerization and reinforced with various concentrations of either EBN or NDEBN nanoplates. These composites exhibited high thermal stability and high thermal conductivity, attributed to the exceptional thermal stability and thermal conductivity inherent in nanodiamond materials. In addition, inserting nanodiamond particles between BN layers prevented the BN nanosheet from forming agglomerates. We also found that nanodiamond particles improved dynamic mechanical properties by acting as a crack pinning role, which could restrict the molecular mobility of the epoxy.
TL;DR: In this paper, a difunctional benzoxazine with o-trifluoroacetamide functionality has been synthesized via Mannich condensation, and the chemical structure of synthesized monomer has also been confirmed by 1H, 13C, and 19F nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR).
Abstract: A novel difunctional benzoxazine with o-trifluoroacetamide functionality has been synthesized via Mannich condensation. The chemical structure of synthesized monomer has also been confirmed by 1H, 13C, and 19F nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The ring-opening polymerization of the resin and the subsequent conversion of the freshly generated polybenzoxazine into polybenzoxazole are studied by FT-IR and differential scanning calorimetry (DSC). In addition to the advantage of low polymerization temperature as other reported o-amide benzoxazines, the o-trifluoroacetamide benzoxazine also exhibits an unexpected lower benzoxazole formation temperature. Furthermore, the resulting fluorinated polybenzoxazole derived from the benzoxazine monomer possesses the combined excellent properties of facile synthesis, easy processability, low dielectric constant, high thermal stability, and long shelf life, evidencing its potential applications in microelect...
TL;DR: In this article, a hybrid filler composed of nanodiamond (ND) nanoclusters-decorated graphene oxide (GO) was fabricated and incorporated in an epoxy matrix using a facile thermoregulatory liquid-liquid extraction method.
Abstract: Novel hybrid fillers composed of nanodiamond (ND) nanocluster-decorated graphene oxide (GO) were fabricated and incorporated in an epoxy matrix using a facile thermoregulatory liquid-liquid extraction method. X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses confirmed a chemical bonding between the (3-aminopropyl)triethoxysilane-functionalized ND and (3-glycidyloxypropyl)trimethoxysilane-functionalized GO. The morphology of the hybrid filler (GN) was characterized by field-emission transmission electron microscopy. ND nanoclusters with an average diameter of 50–100 nm were uniformly grown on the GO surface. The hybrid filler provided significant enhancement of mechanical properties, such as flexural strength, flexural modulus, and fracture toughness. In particular, the epoxy composite containing 0.1 wt% of GN hybrid exhibited a stronger mechanical behavior compared to that containing 0.2 wt% of GO. As the GN loading increased, the thermal stability, the integral procedural decomposition temperature, and the activation energy increased as well. The toughening mechanism was illustrated by a microcrack theory based on the microscopic analysis of the fracture surfaces. The presence of ND nanoclusters not only hindered the aggregation of the GO sheets, but also played a crack pinning role in the polymer-matrix composites, which could significantly enhance its fracture toughness.
TL;DR: In this article, a thin and lightweight silica filled in polyimide (PI) nanofibers membrane is prepared by electrospinning, which significantly improves the safety of lithium-ion batteries when used as a separator.