Enhanced energy density in polyetherimide nanocomposite film at high temperature induced by electrospun BaZrTiO_(3) nanofibers

Polymer dielectrics which possess excellent dielectric properties such as high breakdown strength,flexibility,and facile processability are considered as promising materials for advanced electrostatic capacitors.However,most dielectric polymers have unsatisfactory energy storage performances at high-temperature environments.Here,polyetherimide(PEI) nanocomposite films contained with electrospun Ba(Zr_(0.79)Ti_(0.21))O_(3) nanofibers(BZTNFs) are fabricated by common solution casting method.The dielectric properties,especially the breakdown strength of the BZTNFs/PEI nanocomposites,are characterized,yet improvement is only in the small loading ones.The energy storage performance of the 0.5 vol% and1.0 vol% BZTNFs content nanocomposite is further investigated from 25 to 150℃.With the introduction of small loading BZTNFs,the dielectric permittivity and electric displacement of the nanocomposite are improved at all evaluated temperatures.The 1.0 vol% BZTNFs/PEI possesses a maximal discharged energy density of6.05 J·cm^(-3) with high efficiency of 94.9% at 25℃,then falls to 3.34 J·cm^(-3) with efficiency of 54.6% at 150℃ for the larger remnant displacement.Apparently,the relaxation ferroelectric nanofller of BZTNFs is much effective in increasing the dielectric permittivity of nanocomposite,but its capacity to restrict the migration of the charge carriers at high temperatures is weaker than that of the nanofillers with wider bandgap.The complementation of both kinds of the nanofillers probably provides an approach to available high-temperature dielectric films.

Heat-resistant Al_(2)O_(3) nanowire-polyetherimide separator for safer and faster lithium-ion batteries

Poor heat/flame-resistance of polyolefin(e.g.,polyethylene and polypropylene)separators and high flammability of organic electrolytes used in today’s lithium-ion batteries(LIBs)may trigger rare yet potentially catastrophic safety issues.Here,we mitigate this challenge by developing a heat-resistant and flame-retardant porous composite membrane composed of polyetherimide(PEI)and Al_(2)O_(3) nanowires(NWs).The membranes are fabricated based on an industrially scalable non-solvent-induced phase separation process,which results in an intimately interconnected porous network of Al_(2)O_(3) NWs and PEI.The produced composite membranes exhibit excellent flexibility,thermal stability,and flame-retardancy.Importantly,the composite membranes exhibit minimal thermal shrinkage and superior tensile strength(16 MPa)at temperatures as high as 200℃,significantly exceeding the performance of conventional polyolefin separators.Compared with commercial separators,their superior wettability and higher ionic conductivity(by up to 2.4 times)when filled with the same electrolyte,larger electrolyte uptake(-190 wt.%),as well as improved cycle and rate performance demonstrated in LiNiMnCoO_(2)(NCM)-based LIBs make them attractive choices for a variety of electrochemical energy storage devices.

Effect of molecular weight on reaction-induced phase separation of epoxy resin modified with fluorocarbon chain terminated polyetherimide

A series of fluorocarbon chain terminated polyetherimide is added to epoxy resin, and the effect of molecular weight on the process of phase separation is studied by time-resolved light scattering (TRLS), differential scanning calorimeter (DSC), scanning microscopy (SEM). The results indicate that the phase separation rate decreases due to the preventing effect in-duced by low surface energy of fluorocarbon chain terminated polyetherimide. In addition, evolu-tion time of morphology is shortened and the domain size decreases with the introduction of fluorocarbon chain terminated polyetherimide. Furthermore, when the molecular weight of fluorocarbon chain terminated polyetherimide increases, the morphology can change from dis-persed phase to co-continuous phase. Thus, changing the molecular weight of fluorocarbon chain terminated polyetherimide can control the morphology of the epoxy/polyetherimide blend, which is of great significance in many industries.

Effect of PEG additives on properties and morphologies of polyetherimide membranes prepared by phase inversion

This study investigated the effect of poly(ethylene glycol)(PEG)additive as a pore-former on the structure formation of membranes and their permeation properties connected with the changes in thermodynamic and kinetic properties in the phase inversion process.The membranes were prepared by using polyetherimide/Nmethyl-2-pyrrolidone/PEG(PEI/NMP/PEG)casting solution and water coagulant.The resulting membranes,prepared by changing the ratio of PEG to PEI,were characterized by scanning electron microscope(SEM)observations,measurements of water flux andγ-globin rejection.The thermodynamic and kinetic properties of the membrane-forming system were studied through viscosity.The pore radius distribution curves were especially obtained by differential scanning calorimetry(DSC).Furthermore,the membranes were characterized for pure water flux and rejection of solute and by SEM observation.The filtration results agreed well with the SEM observations.As expected,PEG with a fixed molecular weight(PEG 600)acted as a pore forming agent,and membrane porosity increased as the PEG content of the casting solution increased.

Enhanced Gas Separation Performance by Embedding Submicron Poly(ethylene glycol) Capsules into Polyetherimide Membrane

Recently, hollow filler as an emerging concept is attracting more attention in preparation of mixed matrix membranes(MMMs). Herein,poly(ethylene glycol) microcapsules(PMC) are synthesized via distillation precipitation polymerization and embedded into the polyetherimide(Ultem■1000) matrix to fabricate MMMs for CO_(2) capture. The PMC exhibits a preferential hollow structure within the Ultem matrix to furnish highways within membrane, and thus achieve high gas permeability. Meanwhile, the favorable affinity of poly(ethylene glycol)(PEG)microcapsule with ether oxygen group(EO) towards CO_(2) enhances the CO_(2) solubility selectivity. Such integration of physical and chemical microenvironments in the as-designed PEG microcapsule affords highly enhanced CO_(2) separation performance. Compared to pristine Ultem■1000, the membrane with 2.5 wt% PMC loading exhibits 310% increment in CO_(2) permeability and 22% increment in CO_(2)/N_(2) selectivity,which shows the promising prospects of designing PEG-containing microcapsules as the filler of MMMs for CO_(2) capture.

Magnetically Recoverable PEI/Titanate@Fe_3O_4 Photocatalysts: Fabrication and Photocatalytic Properties

The magnetically separable ternary polyetherimide/titanate@Fe_3 O_4(PTF) photocatalysts of special heterostructure between magnetite(Fe_3 O_4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe_3 O_4 microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe_3 O_4 microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe_3 O_4 microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe_3 O_4 microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.

Significantly Enhanced Energy Storage Performances of PEI-based Composites Utilizing Surface Functionalized ZrO_(2) Nanoparticles for High-Temperature Application

Polymer dielectrics with a high energy density and an available energy storage capacity have been playing an important role in advanced electronics and power systems. Nevertheless, the use of polymer dielectrics in harsh environments is limited by their low energy density at high temperatures. Herein, zirconium dioxide(ZrO_(2)) nanoparticles were decorated with amino group utilizing 4,4-methylenebis(phenyl isocyanate)(AMEO) and successfully incorporated into polyetherimide(PEI) matrix. The dielectric properties, breakdown strength, and energy storage performances of PEI/ZrO_(2)-AMEO nanocomposites were investigated from 25 ℃ to 150 ℃. It is found that the combination of moderate bandgap ZrO_(2) with modest dielectric constant and polar groups at interface with deep trap can offer an available strategy to simultaneously increase the dielectric constant and breakdown strength of polymer dielectrics. As a result, the composites containing ZrO_(2)-AMEO exhibit excellent energy storage performance at elevated temperatures. Specially, the PEI-based composites with 3 vol% ZrO_(2)-AMEO display a maximum discharged energy density(U_(d)) of 3.1 J/cm^(3) at 150 ℃, presenting 90% higher than that of neat PEI. This study may help to better develop the polymer-based dielectric composite applied at elevated temperatures.

A novel polyethyleneimine-decorated FeOOH nanoparticle for efficient siRNA delivery

Despite the promising prospect of small interfering RNA(siRNA) for the treatment of diverse diseases,it remains challenging to develop novel delive ry materials to desired tissues and cells.In this study,a novel iron oxyhydroxide(FeOOH) nanoparticle(NP) whose surface was modified with branched polyetherimide(PEI) was developed to deliver siRNA into the cancer cells.It was demonstrated that PEI-FeOOH(PFeOOH) efficiently complexed siRNA,mediated effective cellular uptake and endosomal escape,thereby triggering robust gene silencing in vitro.In addition,PFeOOH/siRNA formulation loading with anti-RRM2 siRNA effectively inhibited the growth of tumor tissues,and exhibited excellent safety profiles in vivo.Therefore,this study conceptually provided a FeOOH-based nucleic acid delivery vesicle which can potentially use to achieve diagnosis and therapy simultaneously.