Anion exchange membranes with a semi-interpenetrating polymer network using 1,6-dibromohexane as bifunctional crosslinker

An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.

Fluorinated semi-interpenetrating polymer networks for enhancing the mechanical performance and storage stability of polymer-bonded explosives by controlling curing and phase separation rates

Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.

Semi-Interpenetrating Novolac-Epoxy Thermoset Polymer Networks Derived from Plant Biomass

Bio-based phenol-formaldehyde polymer (BioNovolac) was developed by reacting molar excess of bio-oil/phenolwith formaldehyde in acidic medium. Glycidyl 3,5-diglycidoxybenzoate (GDGB), was prepared by directglycidylation of α-resorcylic acid (RA), a naturally occurring phenolic monomer. GDGB was crosslinked in thepresence of BioNovolac by anionic polymerization. Fourier transform infrared spectroscopy (FTIR) confirmedthe formation of semi-interpenetrating polymer networks. The glass transition temperature and moduli of biobasedcrosslinked systems were observed to increase with increasing GDGB content. Active chain density andmass retention measured by dynamic mechanical analysis (DMA) and Soxhlet extraction, respectively, indicated ahigh crosslink density of the cured networks. Scanning electron microscopy (SEM) images depicted thehomogeneity of the bulk phase. The preparation of bio-based epoxy-novolac thermoset network resulted inreduced consumption of petroleum-based chemicals.

Semi-interpenetrating network anion exchange membranes based on quaternized polyvinyl alcohol/poly(diallyldimethylammonium chloride)

The semi-interpenetrating network anion exchange membranes(AEMs)based on quaternized polyvinyl alcohol(QPVA)and poly(-diallyldimethylammonium chloride)(PDDA)are synthesized.The chemical cross-linking structure is formed between hydroxyl groups of QPVA and aldehyde groups of glutaraldehyde(GA),which makes PDDA more stable embed in the QPVA matrix and also improves the mechanical properties and dimensional stability of AEMs.Due to the phase separation phenomenon of AEMs swelling in water,a microporous structure may be formed in the membrane,which reduces the transmission resistance of hydroxide ions and provides a larger space for the transfer of hydroxide ions,thus improving the conductivity.The ring structure of PDDA is introduced as a cationic group to transfer hydroxide ions,and shields the nucleophilic attack of the hydroxide ions through the steric hindrance effect,which improves alkaline stability.The hydroxide conductivity of semi-interpenetrating network membrane(QPVA/PDDA0.5-GA)is 36.5 mS cm^(-1) at 60℃.And the membrane of QPVA/PDDA0.5-GA exhibits excellent mechanical property with maximum tensile strength of 19.6 MPa.After immersing into hot 3 mol L^(-1) NaOH solutions at 60℃ for 300 h,the OHconductivity remains 78%of its initial value.The semi-interpenetrating network AEMs with microporous structure exhibit good ionic conductivity,mechanical strength and alkaline durability.

Imidazolium group prompted alkaline anion-exchange membrane with high performance for efficient electrochemical CO_(2) conversion

Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been developed to maximize the performance of CO_(2) electrolyzers,despite its role as the core in regulating ion transport and preventing product crossover or fuel loss.Herein,we report the synthesis of alkaline anion-exchange membranes fabricated by poly(vinyl-alcohol)(PVA)and poly[(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)](PQ44)for use in CO_(2) electrolysis.Owing to the unique imidazolium ring structure coupled with a three-dimensional semiinterpenetrating porous internal architecture,the PVA/PQ44-OH-membranes provide a high hydroxide conductivity(21.47 mS cm^(-1)),preferable mechanical property and thermal stability.In particular,the eCO_(2)RR used PVA/PQ44-OH^(-) as electrolyte membrane realized a charming Faradaic efficiency(88%)and partial current density(29 mA cm^(-2))at0.96 VRHE and,delivered the excellent durability over 20 h electrolysis in 0.5 mol L^(-1) KHCO_(3) electrolyte.Notably,it can even enable an ultrahigh current density beyond 100 mA cm^(-2) at^(-1).11 VRHE when the electrolyte was KOH instead,and produced the FEHCOOof 85%at a low potential of0.81 VRHE,superior to both commercial alkaline A201 and acidic Nafion117 membrane.

Semi-interpenetrating polymer networks toward sulfonated poly(ether ether ketone) membranes for high concentration direct methanol fuel cell

Low methanol permeability of proton exchange membranes (PEMs) is greatly important for direct methanol fuel cells (DMFCs). Here, sulfonated poly (ether ether ketone) (SPEEK) based semiinterpenetrating polymer networks (semi-IPNs) are successfully prepared by interpenetrating SPEEK into the in-situ synthesized crosslinking networks. The polymeric networks are formed by the covalent bonds between bromobenzyl groups of bro mo methylated poly (phenylene oxide) and amine groups of diamine linkers as well as the ionic bonds between amine species and sulfonated groups. Two linkers without and with sulfonated groups are applied to fabricate the semi-IPNs. The core properties of the membranes, like phase separation, water uptake, proton conductivity and methanol permeability, are systematically studied and compared. The DMFCs assembled by using the semi-IPN membranes display better performance than Nafion 117 in high concentration methanol solutions. The present work provides a facile way to prepare PEMs with enhanced DMFC performance.

Water spatial distribution in polymer electrolyte membrane fuel cell: Convolutional neural network analysis of neutron radiography

Polymer electrolyte membrane(PEM)fuel cells produce water as byproduct,which may cause electrode“flooding”and reduce cell performance.In operation,water usually builds up downstream in the gas flow channel due to the water production by the oxygen reduction reaction(ORR),leading to a water spatial dis-tribution.In this study,a convolutional neural network(CNN)is presented to analyze neutron radiography images to obtain water spatial variation under various operating conditions.5 and 10 segments of a fuel cell are analyzed for spatial variations.Image pre-processing treatments are carried out to improve the convolutional neural network accuracy to 96.6%.The results show that liquid water emerges at a position around 55%downstream for 50%relative humidity while the entire cell is subject to two-phase flow for 100%relative hu-midity under a co-flow configuration.Large water content is present in most of the segments and the near-outlet segment for the counter-flow and co-flow configurations,respectively.In addition,the quad-serpentine cell exhibits more water accumulation than the single serpentine one in most downstream segments.The convolu-tional neural network results agree well with the data obtained from a pixelation image processing method with an accuracy of 91.8%.Compared with conventional pixelation methods,the convolutional neural network method performs better in speed for high-resolution images.It also shows that the current CNN tool fails to predict local water for small spatial scales,such as 10 segments,which leads to a large error(>27%)in prediction.

Synthesis and Water Uptake of Sulfonated Poly (phthalazinone ether sulfone ketone)/Polyacrylic Acid Proton Exchange Membranes

Novel SPPESK/PAA composite proton exchange membranes with semi-interpenetrating polymer network （sIPN） structure have been synthesized through the in-situ polymerization of acrylic acid （AA） in the presence of sulfonated poly （phthalazinone ether sulfone ketone） （SPPESK）. The composite membranes were identified by FT-IR analysis. Water uptake of the composite membranes was as high as 89.7% at 90℃, nearly one time higher than that of the corresponding SPPESK membrane.

Novel Semi-IPN Gel Electrolyte for Polymer Lithium-ion Battery

A new type of semi-IPN gel electrolyte was prepared by thermal polymerization in this article.The cross-linked PEG200 (MXPEG) was prepared by condensation reaction in the presence of methacryloxypropyltrimethoxysilane (MAPTMS),the condensation product was then blent with PMMA and polymerized to form polymer blends with semi-IPN fabric.Differential scanning calorimetry and X-ray diffraction spectroscopy were used to investigate the thermal transition behavior of the polymer blends prepared.Ion-conducting behaviors and the electrochemical stability window for semi-IPN gel electrolyte were investigated by means ofimpedance spectroscopy and linear sweep voltammetry.The Arrhenius-type relationship was observed in the temperature dependence ofionic conductivity.All the properties shows that the prepared semi-IPN gel electrolyte possesses certain levels of electrolye salt and plasticizer were expected to have applications of gel polymer electrolyte for lithium polymer secondary batteries.

A self-standing,UV-cured semi-interpenetrating polymer network reinforced composite gel electrolytes for dendrite-suppressing lithium ion batteries

A self-standing,flexible and lithium dendrite growth-suppressing composite gel polymer electrolyte membrane was designed for the use of room-temperature lithium ion batteries.The multi-functional composite semi-interpenetrating polymer network(referred to as“Cs-IPN”)electrolyte membrane was fabricated by combining a UV-cured ethoxylated trimethylolpropane triacrylate(ETPTA)macromer with alumina nanoparticles in the presence of liquid electrolyte and thermoplastic linear poly(ethylene oxide)(PEO).The polymer electrolyte membrane exhibits a semi-interpenetrating polymer network structure and a higher room temperature ionic conductivity,which impart the electrolyte with a significant cycling(120 mAh g^(-1)after 200 cycles)and a remarkable rate(137 mAh g^(-1)at 0.1℃,130 mAh g^(-1)at 0.5℃,119 mAh g^(-1)at 1℃ and 100 mAh g^(-1)at 2℃)performance in Li/LiFePO4 battery.More importantly,the polymer electrolyte possesses superior ability to inhibit the growth of lithium dendrites,which makes it promising for next generation lithium ion batteries.

Rapid formation of metal-monophenolic networks on polymer membranes for oil/water separation and dye adsorption

Surface deposition based on metal-phenolic networks(MPNs) has received increasing interest in recent years. The catechol structure is generally considered to be essential to the formation of MPNs. Our most recent results have demonstrated that some kinds of monophenols can form MPNs on substrate surfaces.Herein, we report a fast and effective surface-coating system based on the coordination of 3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid, a kind of monophenol, with Fe^(3+). Compared with other metal ions such as Cu^(2+)and Ni^(2+), Fe^(3+)with stronger electron acceptability can coordinate with the monophenol more strongly to form MPNs, and moreover, the deposition time significantly decreases to 40 min from generally 24 h. It is demonstrated that the deposition process is controlled by the coordination, Fe^(3+)hydrolysis, and deprotonation of the monophenol. The coatings endow substrates such as polypropylene microfiltration membrane with underwater superoleophobicity, which can be applied in oil/water separation with high separation efficiency and great long-term stability. In addition, the coated membranes are positively charged and thus are useful in selective adsorption of dyes. The present work not only provides a novel, fast, and one-step deposition method to fabricate MPNs, but also demonstrates that the fabrication efficiency of monophenol-based MPNs is comparable with that of polyphenol-based MPNs.

基于互穿网络技术构筑环境友好型聚合物电解质膜及其电化学性能

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为反应型乳化剂,丙烯酸丁酯(BA)、丙烯腈(AN)和丙烯酸(AA)为单体,利用互穿网络技术通过乳液聚合法制备了环境友好型聚合物电解质膜(M-ABAA),采用FTIR、XPS、SEM、TEM和TG对M-ABAA进行了表征;通过CV、EIS和充放电测试考察以M-ABAA为电解质膜组装的CR2032电池的电化学性能。结果表明,当m(AMPS)∶m(BA)∶m(AA)∶m(AN)=1∶3∶2∶2时,制备的M-ABAA(M2)的离子电导率为0.98 mS/cm,抗拉强度为7.53 MPa,断裂伸长率为90.4%,吸液率为150%,热收缩率为4%。M2与目前锂离子电池主流的正负极材料(LiCoO_(2)、LiMn_(2)O_(4)、LiFePO_(4)、NCM811)具有较好的相容性,普适性较好。以M2为电解质隔膜,金属锂为负极,分别以LiCoO_(2)和石墨为正极组装成半电池,0.2 C倍率下的首次放电比容量分别为141.3和347.1 mA·h/g,100圈循环后容量保持率分别为94.8%和85.0%;2.0 C倍率下,放电比容量分别为119.8和239.0 mA·h/g。

Estimation of equivalent internal-resistance of PEM fuel cell using artificial neural networks

A practical method of estimation for the internal-resistance of polymer electrolyte membrane fuel cell (PEMFC) stack was adopted based on radial basis function (RBF) neural networks. In the training process, k-means clustering algorithm was applied to select the network centers of the input training data. Furthermore, an equivalent electrical-circuit model with this internal-resistance was developed for investigation on the stack. Finally using the neural networks model of the equivalent resistance in the PEMFC stack, the simulation results of the estimation of equivalent internal-resistance of PEMFC were presented. The results show that this electrical PEMFC model is effective and is suitable for the study of control scheme, fault detection and the engineering analysis of electrical circuits.

PVC/PAN共混超滤膜的研究 Ⅱ.铸膜液组成对膜结构与性能的影响

实验表明,铸膜液浓度、PVC 分子量及其分布主要是通过它们对膜孔大小的影响来影响膜的性能。铸膜液浓度提高,膜孔缩小,截留率提高而透水率下降。这种影响在铸膜液百分浓度低于15%时尤为明显。分子量的均一则有利于膜孔的均一。聚乙二醇因其具有较多的羟基,当被添加到PVC/PAN 共混铸膜液中时,既起交联剂的作用,又起溶胀剂的作用,前者有利三维聚合物网络的形成而提高截留率,后者有利提高开放形孔所占的比例而增大透水率。

具有IPN结构的复合超滤膜在华北油田的应用研究

在复合膜的制备过程中 ,膜材料中高分子聚合物很难混合。作者在聚合物—溶剂—聚合物体系中加入一种增溶剂 ,改变了聚合物在溶液中的聚积状态 ,由于是部分混溶 ,在膜的形成过程中各部分聚合物凝胶机理不一样 ,在表面功能层与下部支撑层之间是一层由两种聚合物交叉互相贯穿的网络结构 (即IPN结构 ) 。

新型聚合物互穿网络PP／PnBA的合成与表征

采用原位聚合法在聚丙烯微孔膜基材内复合聚丙烯酸丁酯（ＰｎＢＡ）制备了一种新型聚合物互穿网络ＰＰ／ＰｎＢＡ。用傅立叶扫描红外光谱、偏光显微镜、扫描电镜、Ｘ射线光电子能谱、广角Ｘ射线衍射及力学拉伸等手段进行了表征。发现复合膜表面ＰｎＢＡ的多少依赖于聚丙烯微孔膜基材表面微孔的量及分布情况，复合膜基本上保持了聚丙烯微孔膜基材的骨架结构，交联聚丙烯酸丁酯填入了几乎全部微孔，成为一个与聚丙烯相互穿的新的连续相，形成了真正互穿网络。复合膜的力学延展性有一定程度的改进。

半互穿网络法制备聚偏氟乙烯复合超滤膜

利用半互穿网络法制备聚偏氟乙烯(PVDF)复合超滤膜,根据膜性能参数及扫描电子显微镜(SEM)结构分析确定,聚乙烯醇(PVA)与戊二醛(GD)发生缩醛化反应构建PVA/PVDF半互穿网络结构的最佳条件为,铸膜液中聚乙烯醇的添加量为4.0%(质量分数)、戊二醛与聚乙烯醇加入量的比率为0.5,筛选出的PVDF/PVA/PVP/GD/NMP=16/4/3/2/75配方制备的半互穿网络结构复合膜性能最佳,纯水通量为612.3L/(m^2.h),接触角48.3°,BSA截留率98.7%,爆破压力1.0MPa,BSA吸附量45.3μg/cm^2,使用X射线光电子能谱仪(XPS)、红外分析测试仪(FTIR)等对制备的膜组成及结构进行了表征,用于处理实际石化废水运行一个月后,水通量为144.4L/(m^2·h),COD去除率为80.4%,浊度去除率为97.2%,与未含这种结构的配方制备的PVDF膜性能参数相比,PVA/PVDF半互穿网络复合膜的水通量增大,亲水性能增强,抗污染、抗反洗能力加强,膜的综合性能明显提高。

聚醋酸乙烯酯(PVAc)/聚离子液体(PILs)半互穿聚合物网络膜的制备及气体分离性能

利用紫外光固化法,制备了聚醋酸乙烯酯(PVAc)/聚离子液体(PILs)半互穿聚合物网络膜,用于CO2/N2的分离,并对其化学结构、形貌及热稳定性进行了表征.结果表明,加入PILs后,半互穿膜的热稳定性增加,并且PILs与PVAc的相容性较好,随着PILs含量的增加,PVAc/PILs半互穿膜的CO2和N2渗透系数和溶解度系数均提高,渗透选择性先增后减,当PILs含量为50%时达到最大值64.20.

用于油水分离的具有IPN结构的耐污染复合超滤膜的研究

在复合膜的制备过程中， 膜材料中高分子聚合物很难混合， 本实验在聚合物－ 溶剂－ 聚合物体系中加入一种增溶剂， 改变了聚合物在溶液的聚积状态， 由于是部分混溶， 在膜的形成过程中各部分聚合物凝胶机理不一样， 在表面功能层与下部支撑层之间是一层由两种聚合物交叉互相贯穿的网络结构（ 即ＩＰＮ 结构） ，

原位共聚合法制备新型聚丙烯基互穿网络及结构与性能的研究

通过用聚丙烯微孔膜含浸混合单体然后原位共聚合的方法成功地制得了新型聚丙烯基互穿聚合物网络复合膜。相分离的共聚物玻璃化转变温度随组成的改变，从而影响到复合膜的模量、断裂行为和屈服行为。