Lithium ion conduction and ion-polymer interaction in poly（vinyl pyrrolidone） based electrolytes blended with different plasticizers

Poly（ethylene oxide）, poly（vinyl pyrrolidone）（PEO/PVP）, lithium perchlorate salt（Li Cl O4） and different plasticizer based, gel polymer electrolytes were prepared by the solvent casting technique. XRD results show that the crystallinity decreases with the addition of different plasticizers. Consequently, there is an enhancement in the amorphousity of the samples responsible for the process of ion transport. FTIR spectroscopy is used to characterize the structure of the polymer and confirms the complexation of plasticizer with host polymer matrix. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. Among the various plasticizers, the ethylene carbonate（EC） based complex exhibits a maximum ionic conductivity value of the order of2.7279 10 4S cm 1. Thermal stability of the prepared electrolyte films shows that they can be used in batteries at elevated temperatures. PEO（72%）/PVP（8%）/Li Cl O4（8%）/EC（12%） has the maximum ionic conductivity value which is supported by the lowest optical band gap and lowest intensity in photoluminescence spectroscopy near 400–450 nm. Two and three dimensional topographic images of the sample having a maximum ionic conductivity show the presence of micropores.     

Self-cleaning Anti-fouling TiO2/Poly(aryl ether sulfone) Composite Ultrafiltration Membranes

A series of novel TiO2/poly(aryl ether sulfone) ultrafiltration membranes with anti-fouling and self-cleaning properties was designed and prepared. First, anti-photocatalytic degraded fluorine contained polv(aryl ether sulfone) matrix(PAES-F) was synthesized. Then the composite membranes were prepared via TiO2 nanopartides and PAES-F polymer matrix by solution blending and non-solvent induced phase inversion methods. Further, separation efficiency, fouling behavior and self-cleaning property of the composite ultrafiltration(UF) membranes were investigated by dead-end filtration experiments using a polyacn lamide solution. The composite UF membranes exhibited outstanding self-cleaning efficiency and anti-photocatalytic degraded property after exposure to simulated sunliglit irradiation.The water flux recovery ratios(FRR)of the optimal composite UF membranes could reach 74.24%, which was attributable to photocatalytic degradation of the organic contaminant by TiO2. And the retention rates of the composite UF membranes could maintain over 97%, which indicated the excellent photocatalytic degradation resistance of the fluorine contained PAES-F matrix. The novel high perfomiance composite UF membranes have a broad application prospect in water treatment.     

Modification and characterization of semi-crystalline poly(vinyl alcohol) with interpenetrating poly(acrylic acid) by UV radiation method for alkaline solid polymer electrolytes membrane

Semi-crystalline poly(vinyl alcohol) was modified by UV radiation with acrylic acid monomer to get interpenetrating poly(acrylic acid) modified poly(vinyl alcohol), PVAAA, membrane. The stability of various PVAAA membranes in water, 2 M CH₃OH, 2 M H₂SO₄, and 40 wt% KOH aqueous media were evaluated. It was found that the stability of PVAAA membrane is stable in 40 wt% KOH solution. The PVAAA membranes were characterized by differential scanning calorimetry, X-ray diffraction, and thermogravimetry analysis. These results show that (1) the crystallinity in PVAAA decreased with increasing the content of poly(acrylic acid) in the PVAAA membranes. (2) The melting point of the PVAAA membrane is reduced with increasing the content of poly(acrylic acid) in the membrane. (3) Three stages of thermal degradation were found for pure PVA. Compared to pure PVA, the temperature of thermal degradation increased for the PVAAA membrane. The various PVAAA membranes were immersed in KOH solution to form polymer electrolyte membranes, PVAAA-KOH, and their performances for alkaline solid polymer electrolyte were conducted. At room temperature, the ionic conductivity increased from 0.044 to 0.312 S/cm. The result was due to the formation of interpenetrating polymer chain of poly(acrylic acid) in the PVAAA membrane and resulting in the increase of charge carriers in the PVA polymer matrix. Compared to the data reported for different membranes by other studies, our PVAAA membrane are highly ionic conducting alkaline solid polymer electrolytes membranes.     

不同锂盐对超支化/梳状复合型聚合物电解质的性能影响研究

利用PVA侧链上的羟基的化学活性, 采用超支化聚胺-酯对改性纳米SiO₂和PVA接枝改性, 并加入不同锂盐,制备了SiO₂-g-HBPAE/PVA-g-HBPAE超支化/梳状复合型聚合物电解质, 利用SEM观察了纳米粒子在基体中的分散情况, 采用DSC、拉伸实验以及介电谱研究了锂盐种类及添加量对复合体系性能的影响. 结果表明, 超支化接枝改善了SiO₂和基体的界面相容性; 磺酸类锂盐在复合材料中表现出自增塑现象, 材料的玻璃化转变温度(T_g)大幅度下降; LiClO₄在基体中的离解能力强于LiCF₃SO₃和 LiN(SO₃CF₃)₂; 当LiCF₃SO₃添加量为20 %(by mass, 下文同)时, 聚合物电解质的室温电导率达到最大值2.58×10^-6 S•cm^-1.     

Y-shaped block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) synthesized by ATRP

Novel Y-shaped block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide),PEG-b-(PNIPAM)_2,were successfully synthesized through atom transfer radical polymerization(ATRP).A difunctional macroinitiator was prepared by esterification of 2,2-dichloroacetyl chloride with poly(ethylene glycol) monomethyl ether(PEG).The copolymers were obtained via the ATRP of N-isopropylacrylamide(NIPAM) at 30℃with CuCl/Me_6TREN as a catalyst system and DMF/H_2O(v/v = 3:1) mixture as solvent.The resulting copo...     

一种新型物理交联型凝胶聚合物电解质的制备与表征

以甲氧基聚乙二醇甲基丙烯酸酯(MPEGM)和十六烷基聚乙二醇甲基丙烯酸酯(HPEGM)为单体, 三乙二醇二甲醚(TEGDME)为增塑剂, 与锂盐(高氯酸锂, LiClO₄)和光引发剂(安息香二甲醚, DMPA)复合制成光敏体系, 经紫外(UV)固化得到物理交联型凝胶聚合物电解质(GPE)薄膜. 用红外(IR)光谱、差热分析(DSC)、拉伸测试和交流阻抗(AC) 等方法对聚合物基体和电解质的性能进行了研究.结果表明: 当共聚物P(MPEGM-co-HPEGM)中HPEGM含量为50%(w)时, 十六烷基链段(C₁₆)在聚氧化乙烯(PEO)链段静电斥力的作用下发生聚集, 自组装形成了物理交联, 提高了共聚物的空间稳定性; 温度和电解质中各组分的含量对电导率均有较大的影响, 综合性能较好的电解质在30℃时电导率可达0.87×10^-3 S·cm^-1; 采用循环伏安法测得该电解质的电化学窗口为0~4.5 V (vs. Li/Li⁺), 可以满足锂离子电池的应用要求; 组装成的LiFePO₄/GPE/Li电池, 在30℃下以0.1 C和0.2 C倍率进行充放电测试, 首次放电容量分别为154.7和148.0 mAh·g^-1.     

Molecular iodine preconcentration and determination in aqueous samples using poly(vinylpyrrolidone) containing membranes

Membranes for preconcentration of molecular iodine were developed by two different routes: (i) UV-grafting of 1-vinyl-2-pyrrolidone in the pores of microporous poly(propylene) host membrane (grafted membrane), and (ii) physical immobilization of preformed poly(vinylpyrrolidone) (PVP) in a plasticized cellulose triacetate matrix to form the polymer inclusion membrane (PVP-PIM). The UV-grafted PVP-membrane was found to be hydrophilic (water uptake capacity = 166 wt.%), while the PVP-PIM was found to be highly hydrophobic (≈2 wt.%). PVP-PIM was found to uptake only I₂ from aqueous sample whereas I₂ and I₃⁻ were sorbed in the grafted membrane. This selectivity of PVP-PIM towards I₂ was attributed to its hydrophobicity that allows only neutral I₂ to interact with PVP in the membrane matrix. Thus, the selective preconcentration and quantitative determination of I₂ in aqueous sample was carried out using PVP-PIM. As PVP-PIM was optically transparent, the characteristic absorbance of PVP–I₂ complex (λ_max = 361 nm) could be used for quantitative determination of I₂ in the membrane. The instrumental neutron activation analysis (INAA) of the I₂-loaded PIM samples indicated that 82% could be sorbed into the PIM samples from the solution within 10 min of equilibration time. This membrane was applied to I₂ determinations in the samples of ¹³¹I radiotracer. The concentration level of iodine species in these samples were in sub-ppb level. Therefore, these samples were ideal for testing the preconcentration efficiency of the membrane towards I₂ by monitoring the radioactivity of ¹³¹I. The amounts of I₂ in the aqueous samples were standardized by conventional solvent extraction of I₂ with the chloroform for validating the preconcentration efficiency of PVP-PIM. The detection limit of I₂ in aqueous samples by INAA hyphenated with PVP-PIM was found to be 0.3 ppb for a sample size of 25 mL.     

Alkaline Zn-air and Al-air cells based on novel solid PVA/PAA polymer electrolyte membranes

High ionic conducting solid polymer electrolyte membranes (SPEM) had been successfully prepared from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The solution casting method yielded highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The room temperature ionic conductivity of the alkaline PVA/PAA polymer electrolyte membranes was in the range of 0.142–0.301 S cm⁻¹ depending on the composition. The cyclic voltammetry analysis was carried out using Zn|SPEM|Zn and Al|SPEM|Al cells. The analysis results revealed the excellent electrochemical stability of these newly developed alkaline solid PVA/PAA polymer electrolyte membranes. Metal-air fuel cells were also prepared from the alkaline solid PVA/PAA polymer electrolyte membranes. The electrochemical cell performance was evaluated based on Zn-air and Al-air cells at C/10 and C/5 discharge rates. The experimental results exhibited high percent of utilization for metal powders at room temperature. It was up to 90% for Zn-air cell when assembled with PVA:PAA = 10:7.5 polymer electrolyte membrane and discharged at C/10 rate. The power density could be as high as 50 mW cm⁻² at room temperature. However, the cell percent utilization was reduced to 73% with the same composition electrolyte membrane when C/5 discharge rate was tested.     

双(三氟甲基磺酰)亚胺钠基聚合物电解质在固态钠电池中的性能

采用简单的溶液浇铸法制备出由双（三氟甲基磺酰）亚胺钠（NaTFSI）/聚氧乙烯（PEO）构筑的固态聚合物电解质（SPE）,并针对其相转变、结晶性、热稳定性、电导率以及电化学稳定性等基础理化及电化学性质进行了系统表征。结果表明,NaTFSI/PEO（[EO]/[Na⁺]=15）SPE具有相对高的电导率（σ ≈ 10^-3 S·cm^-1,80℃）、高的耐氧化能力（4.86 V vs Na⁺/Na）和热稳定性高达350℃。电池测试结果表明,该NaTFSI基SPE不仅对金属钠电极能够呈现出优异的界面稳定性,而且在Na|SPE|NaCu_1/9Ni_2/9Fe_1/3Mn_1/3O₂电池中展现出良好的循环和倍率性能。     

An inverse gas chromatographic characterization of polypyrrole-coated poly(vinyl chloride) powder particles

Polypyrrole-coated poly(vinyl chloride) powder particles (PPy-PVC) were prepared by the in-situ chemical polymerization of pyrrole in aqueous solutions in the presence of PVC powder particles using the method of Ouyang and Chan [Polymer 39 (1998) 1857] and characterized by inverse gas chromatography (IGC). By employing n-alkane, 1-heptene, chloroform and tetrahydrofuran molecular probes, the dispersive and acid–base components of the surface energy of the composite materials were estimated at infinite dilution. The values of the dispersive contribution to the surface energy (γ_S^d), at 50 °C, range from 30.3 to 43.5 mJ/m² for the composites, which is much lower than the value of 83.2 mJ/m² obtained for para-toluene sulfonate-doped polypyrrole (PPyTS) bulk powder. This indicates that the injected molecules probe both polypyrrole and the underlying PVC, thus indicating that the conducting polymer is rather patchy at the surface of the insulating polymer substrate. This conclusion supports the previous results obtained by X-ray photoelectron spectroscopy (XPS) [19], indicating that both the coating PPyTS and the substrate PVC are detected by their elemental markers nitrogen and sulfur, and chlorine, respectively.     

燃料电池用聚乙烯醇基碱性聚合物电解质膜的制备及其性能

通过在不同浓度KOH溶液中进行掺杂,制备出了聚乙烯醇(PVA)、聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)和聚乙烯醇/聚乙二醇二甲醚(PVA/PEGDE)碱性聚合物电解质膜详细考察了膜的外观形貌、微观结构、热稳定性、离子电导率和化学稳定性等.结果表明,PVA与PVP以及PEGDE具有很好的相容性,所制备的复合膜断面致密...     

Poly(vinyl alcohol) Chains Grafted onto the Surface of Copper Oxide Nanoparticles: Application in Synthesis and Characterization of Novel Optically Active and Thermally Stable Nanocomposites Based on Poly(amide-imide) Containing N-trimellitylimido-L-valine Linkage

Green polymer nanocomposites (NCs) show unique properties of combining the advantages of nanofillers and organic polymers. In this study, in order to control the dispersion of nanoparticles (NPs) in a polymer matrix, first, poly(vinyl alcohol) (PVA) as a green modifier was grafted on the surface of the CuO NPs to obtain CuO-PVA nanohybrid. Then poly(amide-imide) (PAI) was synthesized by the direct step growth polymerization of N-trimellitylimido-L-valine and 4,4′-methylenebis(3-chloro-2,6-diethylaniline) in ionic liquid medium. Finally, CuO-PVA hybrids were incorporated into the PAI matrix using ultrasonic technique for the preparation of PAI/CuO-PVA NCs. The obtained PAI/CuO-PVA NCs were characterized by different methods. The results of thermogravimetric analysis showed that thermal stability of the NCs was enhanced by incorporation of CuO-PVA nanohybrid compared to the pure PAI.     

A new composite polymer electrolyte based on poly(ethyleneoxide)/ polysiloxane/BMImTFSI/organomontmorillonite

Composite polymer electrolytes based on poly(ethylene oxide)-polysiloxane/l-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide/organomontmorillonite(PEO-PDMS/1L/OMMT) were prepared and characterized.Addition of both an ionic liquid and OMMT to the polymer base of PEO-PDMS resulted in an increase in ionic conductivity.At room temperature,the ionic conductivity of sample PPB100-OMMT4 was 2.19×10~3 S/cm.The composite polymer electrolyte also exhibited high thermal and electrochemical stability and may potentially be applied in lithium batteries.     

高稳定性化学交联聚乙烯醇/聚乙烯吡咯烷酮碱性固体电解质膜

碱性固体电解质膜的稳定性是影响其在电化学领域应用的一个重要因素.本文在前期研究工作的基础上,通过直接共混和化学交联修饰制备出了聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)碱性聚合物电解质膜.采用傅里叶变换红外(FTIR)光谱、热重分析(TGA)、扫描电镜(SEM)和交流阻抗等方法详细考察了复合膜的分子结构、热稳定性、化学稳定性、氧化稳定性和尺寸稳定性.红外光谱结果表明,PVP成功地混入聚合物基体中,在1672cm-1处表现出来自于PVP第I带C襒O的强吸收峰.TGA结果表明,提高掺杂的KOH溶液浓度对PVA/PVP碱性膜的热稳定性没有明显影响.SEM分析结果表明,复合膜经高温、高浓度碱(80℃,10mol·L-1)处理后,其断面结构仍致密均匀,未出现类似小孔等膜降解情况,此时膜电导率(1.58×10-3S·cm-1)相比室温相同碱液时提高91.5%,表明PVA/PVP膜具有很好的耐碱化学稳定性.同时,PVA/PVP碱性膜表现出良好的抗氧化性,在60℃的3%和10%H2O2溶液中处理均没有观察到明显的质量损失,150h后仍能保持原膜质量的89%和85%.此外,由于膜内形成致密的内互交联网络结构,复合膜在水中800h之后也表现出很好的同向性和电导率稳定性.     

Stability and ageing of plasma treated poly(tetrafluoroethylene) surfaces

In this study CO₂, H₂/H₂O and H₂O low pressure plasma treatment of poly(tetrafluoroethylene) (PTFE) foils and of thin plasma deposited fluorocarbon polymer (PDFP) films with a structure close to PTFE was investigated. The properties of the plasma were analyzed by mass spectroscopy (MS) and optical emission spectroscopy (OES). The modified fluorocarbon surfaces were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy, spectroscopic ellipsometry, electrokinetic measurements and dynamic contact angle measurements in order to find optimized treatment conditions. The results of the surface modification were compared with respect to the efficiency of the plasma treatment and the stability of the modification effect at different ambient conditions. It was shown that the H₂O plasma treatment is the most effective process for the intended modification. The hydrophobic PTFE surface was converted into a more hydrophilic one. The introduced radicals after the H₂O plasma treatment can be utilized subsequently for post plasma reactions such as grafting processes.     

The thermal degradation of poly(diethyl fumarate)

The kinetics and mechanism of the thermal degradation of poly(diethyl fumarate) (PDEF) were studied by thermogravimetry, as well as by analysis of the thermolysis volatiles and polymer residue. The characteristic mass loss temperatures were determined, as were the overall thermal degradation activation energies of three PDEF samples of varying molar mass. Ethylene and ethanol were present in the thermolysis volatiles at degradation temperatures below 300 °C, while diethyl fumarate was also evidenced at higher degradation temperatures. The amount of monomer increased with increasing degradation temperature. The dependence of the molar mass of the residual polymer on the degradation time and temperature was established and the number of main-chain scissions per monomer unit, s/P₀, calculated. A thermal degradation mechanism including de-esterification and random main-chain scission is proposed. The thermal degradation of PDEF was compared to the thermolysis of poly(ethyl methacrylate) (PEMA), poly(diethyl itaconate) (PDEI) and poly(ethyl acrylate) (PEA).     

Remarkably improved toughness and thermal stability of poly (vinyl chloride) (PVC)/poly (α-methylstyrene-acrylonitrile) (α-MSAN) blend with the assistance of two impact modifiers

The key drawback of impact modifier-toughened polymer is that the improved toughness is accompanied by loss in stiffness. Surprisingly, poly (vinyl chloride) (PVC)/poly (α-methylstyrene-acrylonitrile) (α-MSAN) blend was toughened without loss in stiffness by simply combining two impact modifiers-chlorinated polyethylene (CPE) and acrylic resin (ACR). The prepared blend's impact strength was 3.0 times higher than PVC/α-MSAN/CPE blend and 18.6 times higher than pure PVC/α-MSAN blend. An impressive thermal stabilizing effect was also achieved when CPE and ACR were combined. The improved toughness could be attributed to the overlap of the stress field between different impact modifiers, which help to form the continuum percolation of stress volume under impact loading.     

Improving electrochemical performance of poly(vinyl butyral)-based electrolyte by reinforcement with network of ceramic nanofillers

This study has concerned the development of polymer composite electrolytes based on poly(vinyl butyral) (PVB) reinforced with calcinated Li/titania (CLT) for use as an electrolyte in electrochemical devices. The primary aim of this work was to verify our concept of applying CLT-based fillers in a form of nano-backbone to enhance the performance of a solid electrolyte system. To introduce the network of CLT into the PVB matrix, gelatin was used as a sacrificial polymer matrix for the implementation of in situ sol–gel reactions. The gelatin/Li/titania nanofiber films with various lithium perchlorate (LiClO₄) and titanium isopropoxide proportions were initially fabricated via electrospinning, and ionic conductivities of electrospun nanofibers were then examined at 25 °C. In this regard, the highest ionic conductivity of 2.55 × 10⁻⁶ S/cm was achieved when 10 wt% and 7.5 wt% loadings of LiClO₄ and titania precursor were used, respectively. The nanofiber film was then calcined at 400 °C to remove gelatin, and the obtained CLT film was then re-dispersed in solvated PVB-lithium bis(trifluoromethanesulfonyl)imide (PVB-LiTFSI) solution before casting to obtain reinforced composite solid electrolyte film. The reinforced composite PVB polymer electrolyte film shows high ionic conductivity of 2.22 × 10⁻⁴ S/cm with a wider electrochemical stability window in comparison to the one without nanofillers.

     

Morphology control of sulfonated poly(ether ketone ketone) poly(ether imide) blends and their use in proton-exchange membranes

Polymer blends based on sulfonated poly(ether ketone ketone) (SPEKK) as the proton-conducting component and poly(ether imide) (PEI) as the second component were considered for proton-exchange membranes (PEMs). The PEI was added to improve the mechanical stability and lower the water swelling in the fuel cell environment. Membranes were cast from solution using N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc). The ternary, polymer/polymer/solvent, phase diagram was determined to provide guidance on how to control the morphology during solvent casting of blend membranes.

For blends of SPEKK (ion-exchange capacity = 2 mequiv/g) with PEI as the minority component, the morphology consisted of dispersed particles of 0.5–6 μm. Larger particles were achieved by increasing the PEI content and/or lowering the casting temperature. High-temperature annealing after solution casting did not affect the morphology of blend membranes, due to the low mobility and compatibility of the two polymers.

The possible use of SPEKK/PEI blends in PEMs is discussed in terms of existing theories of ion transport in polymers.     

Effect of salts on the electrical conductance of a fluorine-containing poly(carboxylic acid), PPFNA

Electrical conductance and other solution properties of aqueous solutions of a fluorine-containing poly(carboxylic acid), (poly(9H,9H-perfluoro-2,5-dimethyl-3,6-dioxa-8-nonenoic acid), PPFNA) were studied with special attention to the salt effect. This polymer dissociated strongly resulting in a low pH value in unneutralized state (β = 0, β: degree of neutralization). The specific conductance was the highest at β = 0 and decreased as β increased. A considerable increase in conductance was observed by titrating NaCl at low β, because large amounts of bound protons were released by addition of NaCl. The amounts of released protons exceeded those originally dissociated at β = 0. Such an anomalous proton liberation suggests that this polymer is a fairly strong polyacid but not a typical one such as poly(styrene sulfonic acid). Under fully neutralized state (β = 1), however, the solution conductance was lower than the sum of the polymer and NaCl added, due to polyion–salt ion interaction.