Effects of Polyethylene Oxide Concentration on the Size of Beads in Electrospun Beaded Nanofibers

Embedding particle drugs in beaded nanofibers by electrospinning has been shown a potential approach to control drug release in tissue engineering. The bead size is one of the critical parameters in controlling the drug release rate. In this study,the relationship between polymer concentration and beads size was investigated. Aqueous polyethylene oxide( PEO) solutions with different concentrations were prepared to obtain various beaded nanofibers by electrospnning. Optical microscope and scanning electron microscope( SEM) were used to observe the variation tendency of bead size. With an increase in the polymer concentration,the diameter of fibers between beads became bigger,while the fiber uniformity improved. In addition, the polymer concentration influenced the distribution of bead diameter. Higher polymer concentration would reduce the possibility of small-sized beads formation and improve the uniformity of bead diameter. The study provides a possible way to control the size of beads,which is helpful for further research on the control of particle drug release.

Incorporating multifunctional LiAlSiO_(4) into polyethylene oxide for high-performance solid-state lithium batteries

High ionic conductivity,good electrochemical stability,and satisfactory mechanical property are the crucial factors for polymer solid state electrolytes.Herein,fast ion conductor LiAlSiO_4(LASO) is incorporated into polyethylene oxide(PEO)-based solid-state electrolytes(SSEs).The SSEs containing LASO exhibit enhanced mechanical properties performance compared to pristine PEO-LiTFSI electrolyte.A reduced melting transition temperature of 40.57℃ is enabled by introducing LASO in to PEO-based SSE,which is beneficial to the motion of PEO chain and makes it possible for working at a moderate environment.Coupling with the enhanced motion of PEO,dissociation of the lithium salt,and conducting channel of LASO,the optimized composite polymer SSE exhibits a high ionic conductivity of 4.68×10^(-4),3.16×10^(-4) and 1.62×10^(-4) S cm^(-1) at 60,50 and 40℃,respectively.The corresponding LiFePO_4//Li solid-state battery exhibits high specific capacities of 166,160 and 139 mAh g^(-1) at 0.2 C under 60,40 and 25℃.In addition,it remains 130 mAh g^(-1) at 4.0 C,and maintains 91.74% after 500 cycles at 1.0 C under 60℃.This study provides a simple approach for developing ionic conductor-filled polymer electrolytes in solid-state lithium battery application.

Ionic conductivity study on electron beam irradiated polyacrylonitrile-polyethylene oxide gel

Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.

Polyethylene Oxide-Coated Electrospun Polyimide Fibrous Seperator for High-Performance Lithium-Ion Battery

A polyethylene oxide （PEO）-coated polyimide （PI） membrane was prepared by electrospinning method followed by a dip-coating and drying process for high-performance lithium-ion batteries （LIB）. 8emicrystal PEO was covered on the surface of the fibers and partially enmeshed in PI matrix, which formed unique porous structures. The pores with an average size of 4.1 μm and a porosity of 90% served as ion transport channels. Compared with the cell with Celgard 2400 membrane, the half-cell using PEO-coated P1 membrane as a separator exhibits excellent electrochemical performance both at room temperature and at low temperature. The electrolyte uptaking rate of PEO-coated PI membrane was 170% and the ionic conductivity was 3.83 × 10^-3 S cm^-1. PEO-coated PI membrane possessed 5.3 V electrochemical window. The electrode-electrolyte interfacial resistance was 62.4 Ω. The capacity retention ratios with PEO- coated PI membrane were 86.4% at 5 C and 73.5% at 10 C at 25 ℃ and 75% at 5 C at 0 ℃. Furthermore, the cell using the separator demonstrates excellent capacity retention over cycling. These advanced characteristics would boost the application of the PEO-coated PI membrane for high-power lithium ion battery.

Poly(m-phenylene isophthalamide)-reinforced polyethylene oxide composite electrolyte with high mechanical strength and thermostability for all-solid-state lithium metal batteries

Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with flexibility,easy processability,low cost and especially strong ability to dissolve lithium salts have been regarded as promising alternatives to traditional flammable liquid electrolytes in next-generation highsafety and high-energy-density lithium metal batteries.However,the inferior mechanical strength and thermostability of PEO-based SPEs will raise the lithium dendritic penetration issue,further leading to the short circuit in batteries.In this work,aiming at enhancing the interfacial stability against Li dendrites of PEO-based SPEs,poly(mphenylene isophthalamide)(PMIA)is introduced as a reinforcing phase for the rational design of PEO/PMIA composite electrolyte.Impressively,PMIA chain with meta-type benzene-amide linkages significantly improves the mechanical strength(1.60 MPa),thermal stability(260℃)and ability to inhibit the growth of lithium dendrites(>300 h at 0.1 mA·cm^(-2))of SPEs.Meanwhile,allsolid-state LiFePO_(4)‖PEO/PMlA‖Li cell demonstrates superior electrochemical performance in terms of high specific capacity(159.1 mAh·g^(-1)),remarkable capacity retention(82.2%after 200 cycles at 0.5 C)and excellent safety characteristics.No burning or explosion occurs under pressing,bending and cutting conditions.This work opens a new door in developing high-performance PEObased electrolytes for advanced all-solid-state lithium metal batteries.

Synthesis and Surface Tension Properties of Polyethyleneimine-Polyethylene Oxide Block Copolymers

This paper describes the synthesis, surface tension and dispersancy properties of block copolymer nonionic surfactants comprised of polyethyleneimine (PEI) and polyethylene oxide (PEO) blocks of selected lengths. These block copolymers were prepared by a three step synthetic sequence. Firstly, PEO glycol was converted to its dimethanesulphonylester (dimesyl) derivative by reacting with methanesulphonyl chloride. Then a tri block polymer was prepared by the ring opening polymerization of 2 methyl 2 oxazoline (MeOZO) with the dimesyl PEO derivative. Lastly, linear PEI blocks were obtained by subsequent hydrolysis and purification. 1H NMR spectra confirmed the structures of the intermediate, final products and their purities (>99%). The utility of these block copolymers is described in terms of their surface tension and clay dispersancy measurements as a function of copolymer chain and block length.

The Structure and Properties of Polyethylene Oxide Reinforced Poly(Metaphenylene Isophthalamide)Fibers

In this paper,the efect of poly(ethylene oxide)(PEO)as an additive on the structure and properties of poly(m-phenylene dimethylene terephthalamide)(PMIA)fbers obtained by wet spinning was investigated.The tensile strength of the composite fbers was substantially enhanced compared to the pure PMIA fber.This was due to the fact that the addition of PEO weakens the hydrogen bonding between PMIA molecular chains resulting in an improved orientation of the composite fbers.It was found that the optimum PEO addition was 2%and the tensile strength of the composite fber was 4.74 cN/dtex,which was 76%higher compared to the pure PMIA fber.However,the heat resistance and fame retardancy of the composite fbers were basically unchanged compared to the pure PMIA fber.The modifcation method is simple,with low raw material cost and good stability,and has not only good academic value but also excellent industrial value.

In-situ polymerized PEO-based solid electrolytes contribute better Li metal batteries:Challenges,strategies,and perspectives

Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with good electrochemical stability and excellent Li salt solubility are considered as one of the most promising SPEs for solid-state lithium metal batteries(SSLMBs).However,PEO-based SPEs suffer from low ionic conductivity at room temperature and high interfacial resistance with the electrodes due to poor interfacial contact,seriously hindering their practical applications.As an emerging technology,in-situ polymerization process has been widely used in PEO-based SPEs because it can effectively increase Li-ion transport at the interface and improve the interfacial contact between the electrolyte and electrodes.Herein,we review recent advances in design and fabrication of in-situ polymerized PEO-based SPEs to realize enhanced performance in LMBs.The merits and current challenges of various SPEs,as well as their stabilizing strategies are presented.Furthermore,various in-situ polymerization methods(such as free radical polymerization,cationic polymerization,anionic polymerization)for the preparation of PEO-based SPEs are summarized.In addition,the application of in-situ polymerization technology in PEO-based SPEs for adjustment of the functional units and addition of different functional filler materials was systematically discussed to explore the design concepts,methods and working mechanisms.Finally,the challenges and future prospects of in-situ polymerized PEO-based SPEs for SSLMBs are also proposed.

Studies on the Absorption of NO_2 by Polyethylene Glycol and the Oxidizing Properties of the Resulting Absorbent Product

PEG (Polyethylene glycol average molecular weight 300) is used as absorbent of NO2. The absorption efficiency is found to reach up to 97%. The absorbing product, PEG NO2, can be used to cleave benzyl ethers mildly and selectively to benzaldehyde and corresponding fatty alcohols, showing that PEG is a valuable oxidizing agent of benzyl ethers. As a carrier of NO2.PEG can be recovered and utilized repeatedly after the oxidation.

A General Strategy to Electrospin Nanofibers with Ultrahigh Molecular Chain Orientation

The degree of polymer chain orientation is a key structural parameter that determines the mechanical and physical properties of fibers.However,understanding and significantly tuning the orientation of fiber macromolecular chains remain elusive.Herein,we propose a novel electrospinning technique that can efficiently modulate molecular chain orientation by controlling the electric field.In contrast to the typical electrospinning method,this technique can piecewise control the electric field by applying high voltage to the metal ring instead of the needle.Benefiting from this change,a new electric field distribution can be realized,leading to a non-monotonic change in the drafting force.As a result,the macromolecular chain orientation of polyethylene oxide(PEO)nanofibers was significantly improved with a recordhigh infrared dichroic ratio.This was further confirmed by the sharp decrease in the PEO jet fineness of approximately 80%and the nanofiber diameter from 298 to 114 nm.Interestingly,the crystallinity can also be adjusted,with an obvious drop from 74.9%to 31.7%,which is different from the high crystallinity caused by oriented chains in common materials.This work guides a new perspective for the preparation of advanced electrospun nanofibers with optimal orientation–crystallinity properties,a merited feature for various applications.

Solid-state Al-air battery with an ethanol gel electrolyte

Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), respectively.By studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.

Chitosan as green kinetic inhibitors for gas hydrate formation

The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures.The results indicated that chitosan was a good kinetic inhibitor.The induction time of gas hydrate formation evidently increased with the degree of deacetylation （DD）,however,when DD was higher than 80%,the effect of DD on the induction time was negligible.Moreover,it was found that the molecular weight （MW） of chitosan and the addition of polyethylene oxide （PEO） had little effect on the induction time.The optimal concentration of chitosan was found to be 0.6 wt%.Finally,the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.

3D flame-retardant skeleton reinforced polymer electrolyte for solid-state dendrite-free lithium metal batteries

For solid polymer electrolytes(SPEs),improving their mechanical and electrochemical properties is the key to obtaining batteries with higher safety and higher energy density.Herein,a novel synergistic strategy proposed is preparing a 3D flame-retardant skeleton(3DPA)and adding nano-multifunctional fillers(Li-ILs@ZIF-8).In addition to providing mechanical support for the polyethylene oxide(PEO)matrix,3DPA also has further contributed to the system’s flame retardancy and further improved the safety.Simultaneously,the electrochemical performance is fully guaranteed by rigid Li-ILs@ZIF-8,which provides fast migration channels forLi^(+),reduces the crystallinity of PEO and effectively inhibits lithium dendrites.The limiting oxygen index of the optimal sample(PL3Z/PA)is as high as 20.5%,and the ionic conductivity reaches 2.89×10^(-4) and 0.91×10^(-3) S cm^(-1) at 25 and 55°C,respectively.The assembled Li|PL3Z/PA|Li battery can be cycled stably for more than 1000 h at a current density of 0.1 m A cm^(-2) without short circuit being pierced by lithium dendrites.The specific capacity of the LFP|PL3Z/PA|Li battery was 160.5 m Ah g^(-1) under a current density of 0.5 C,and the capacity retention rate was 90.0%after 300 cycles.

SYNTHESIS AND CHARACTERIZATION OF REACTIVE GRAFT COPOLYMER PDMS-g-(PEO-OH)

A new reactive graft copolymer, poly (dimethyl siloxane)-graft-omega-hydroxyl-poly (ethylene oxide) (PDMS-g-(PEO-OH)), was synthesized by the hydrosilylation reaction of alpha, omega-bifunctional PEO macromonomer (CH2=CH-CH2-PEO-OH) with poly (hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comblike structure as indicated by the result of detailed characterization and the needed reactivity as demonstrated by the result of esterification between PDMS-g-(PEO-OH) and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer materials.

An asymmetric bilayer polymer-ceramic solid electrolyte for highperformance sodium metal batteries

Manufacturing an excellent solid electrolyte compatible with a high-voltage cathode is viewed as a critical tactic for improving the energy density of solid-state sodium-ion batteries(SSIBs).A novel asymmetric bilayer solid electrolyte of the PEO-SN-NaClO_(4)|NZSP-NSO with an anti-reduction PEO-SN-NaClO_(4)layer close to the Na side is constructed by solution casting.The ionic conductivity is enhanced by using succinonitrile(SN)in polyethylene oxide(PEO)polymer electrolyte.The anti-oxidation layer of Na_(3)Zr_(2)Si_(2)PO_(12)with Na_(2)SiO_(3)(NZSP-NSO)is served as the support of the membrane on the cathode,which could improve the interface compatibility and electrochemical performance of SSIBs.The asymmetric bilayer solid electrolyte simultaneously features a wide electrochemical stability window(4.65 V vs.Na+/Na)and a high conductivity(2.68×10^(-4) S cm^(-1)).Furthermore,the solid electrolyte demonstrates stable Na plating/stripping over 700 h and remarkably improves cycling stability in Na/Na_(3) V_(2)(PO_(4))_(3) batteries with an ultra-high capacity retention of 99.6%after 100 cycles at 50℃and 0.5 C.This study provides an effective strategy for designing asymmetric high sodium ion conductivity solid-state electrolytes for high-performance SSIBs.

Electrospinning of Bead-on-String Sodium Alginate Nanofibrous Membrane

Electrospun sodium alginate(SA)fibers,which are always considered as a kind of biocompatible and non-toxic materials,have great potential application in the biomedical field due to high specific surface area and large porosity.However,in order to facilitate the electrospinning process,another polymer should be added into the SA solution.The effect of the added polymer of polyethylene oxide(PEO),SA,and ethanol on tuning the beaded structure of electrospun fibers was evaluated.Pure SA electrospun membrane with a beaded structure was prepared.The results show that PEO can facilitate the fabrication,but the mass fractions of SA and ethanol are positively correlated with the bead forming.When the mass fraction of ethanol in the solution was 15.0%(mass fractions of SA and PEO were 1.0%and 1.5%,respectively),the average diameter of the obtained beads was 824.80 nm,and the average length was 2.88μm.Besides,the fibrous structure can be maintained even after the removal of PEO by ethanol.After removing PEO,the average diameter of the beads was reduced to 578.73 nm and the average length was reduced to 2.34μm.

Synthesis and application of bilayer-surfactant-enveloped Fe_3O_4 nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe3O4 nanoparticles with high magnetization（85 emu·g-（-1）） and high crystallinity were synthesized using polyethylene glycol-4000（PEG（4000）） as a carbon source.Fe3O4 water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG（4000） as dispersants.Analyses using X-ray photoelectron spectroscopy,X-ray diffraction,and Fourier-transform infrared spectroscopy indicate that the Fe3O4 nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG（4000）.Transmission electron microscopy,vibrating sample magnetometry,and particle-size analysis results indicate that the coated Fe3O4 nanoparticles also retain the good saturation magnetization of Fe3O4（79.6 emu·g^-1） and that the particle size of the bilayer-surfactant-enveloped Fe3O4 nanoparticles is 42.97 nm,which is substantially smaller than that of the unmodified Fe3O4 nanoparticles（486.2 nm）.UV-vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L^-1,which indicates that the ferrofluids are highly stable.

Designing metal-organic framework fiber network reinforced polymer electrolytes to provide continuous ion transport in solid state lithium metal batteries

Polyethylene oxide(PEO)-based solid-state electrolytes are considered ideal for electrolyte materials in solid-state lithium metal batteries(SSLMBs).However,practical applications are hindered by the lower conductivity and poor interfacial stability.Here,we propose a strategy to construct a three-dimensional(3D)fiber network of metal-organic frameworks(MOFs).Composite solid electrolytes(CSEs)with continuous ion transport pathways were fabricated by filling a PEO polymer matrix in fibers containing interconnected MOFs.This 3D fiber network provides a fast Li+transport path and effectively improves the ionic conductivity(1.36×10^(-4) S·cm^(-1),30℃).In addition,the network of interconnected MOFs not only effectively traps the anions,but also provides sufficient mechanical strength to prevent the growth of Li dendrites.Benefiting from the advantages of structural design,the CSEs stabilize the Li/electrolyte interface and extend the cycle life of the Li-symmetric cells to 3000 h.The assembled SSLMBs exhibit excellent cycling performance at both room and high temperatures.In addition,the constructed pouch cells can provide an areal capacity of 0.62 mA·h·cm^(-2),which can still operate under extreme conditions.This work provides a new strategy for the design of CSEs with continuous structure and stable operation of SSLMBs.

Nb_(2)CT_(x)MXene boosting PEO polymer electrolyte for all-solid-state Li-S batteries:two birds with one stone strategy to enhance Li+conductivity and polysulfide adsorptivity

All-solid-state lithium-sulfur(Li-S)battery is regarded as next-generation high energy density and safety battery system.The key challenge is to develop a compatible high-performance solid-state electrolyte.Herein,a two birds with one stone strategy is proposed to simultaneously enhance Li+conductivity and polysulfide adsorptivity of poly(ethylene oxide)(PEO)-based polymer electrolyte via the integration of Nb_(2)CT_(x)MXene.Moreover,the sheet size of Nb_(2)CT_(x)MXene is crucial for the enhancement of Li^(+)conductivity and polysulfide adsorptivity,attributing to the difference in a specific surface area related to the percolation effect.By tuning the sheet size of Nb_(2)CT_(x)MXene from 500-300 nm to below 100 nm,the ionic conductivity of the PEO electrolyte is increased to2.62×10^(-4)S·cm^(-1)with improved Li+transference number of 0.37 at 600C.Furthermore,theoretical calculation and X-ray photoelectron spectroscopy(XPS)conjointly prove that poly sulfides could be effectively adsorbed by Nb2CTxnanosheets via forming Nb-S bonding to inhibit their shuttle in the PEO framework.As a result,the all-solid-state Li-S cell exhibits an initial capacity of 1149 mAh·g^(-1)at 0.5C and good cycling stability with 491 mAh·g^(-1)after 200 cycles.The results demonstrate the necessity of polysulfide inhibition and the application of Nb_(2)CT_(x)MXene in PEO-based electrolytes for all-solid-state Li-S batteries.

Electrochemical Performance of PEO_(10)LiX-Li_2TiO_3 Composite Polymer Electrolytes

The conductivities of polyethylene oxide (PEO)-based polymer electrolytes (PE) can be improved by the addition of inorganic inert powder. The composite polymer electrolytes (CPE) PEO10LiX (X=4ClO- or 322N(CFSO)-)-Li2TiO3 were prepared by solution casting with inorganic solid electrolyte Li2TiO3 powder as a filler. Results showed that the conductivities of PEO10LiClO4-3wt% Li2TiO3 and PEO10LiN(CF3SO2)2-10wt% Li2TiO3 at 30 ℃ were 8.6×10-6 and 5.6×10-5 S·cm-1, respectively. The conductivities of CPE increased with the decrease of filler抯 particle size. The ionic conduction mechanism analysis showed that there may be three conduction routes in the CPE, i.e., PEO bulk, polymer-filler interface and Li2TiO3 crystal.