Durable Multiblock Poly(biphenyl alkylene) Anion Exchange Membranes with Microphase Separation for Hydrogen Energy Conversion

Anion exchange membrane fuel cells (AEMFCs) and water electrolysis (AEMWE) show great application potential in the field of hydrogen energy conversion technology. However, scalable anion exchange membranes (AEMs) with desirable properties are still lacking, which greatly hampers the commercialization of this technology. Herein, we propose a series of novel multiblock AEMs based on ether-free poly(biphenyl ammonium-b-biphenyl phenyl)s (PBPA-b-BPPs) that are suitable for use in high performance AEMFC and AEMWE systems because of their well-formed microphase separation structures. The developed AEMs achieved outstanding OH⁻ conductivity (162.2 mS cm⁻¹ at 80 °C) with a low swelling ratio, good alkaline stability, and excellent mechanical durability (tensile strength >31 MPa and elongation at break >147 % after treatment in 2 M NaOH at 80 °C for 3750 h). A PBPA-b-BPP-based AEMFC demonstrated a remarkable peak power density of 2.41 W cm⁻² and in situ durability for 330 h under 0.6 A cm⁻² at 70 °C. An AEMWE device showed a promising performance (6.25 A cm⁻² at 2 V, 80 °C) and outstanding in situ durability for 3250 h with a low voltage decay rate (<28 μV h⁻¹). The newly developed PBPA-b-BPP AEMs thus show great application prospects for energy conversion devices.     

Preparation and Properties of Nanoporous Triblock Copolymer Membranes

“ Unplug those pores!” could be a slogan common to cosmetologists and polymer chemists. Membranes with nanochannels can be obtained by first forming a film by casting a solution of a triblock and homopolymer mixture, then selectively cross-linking domains in the film by photolysis, and finally forming nanochannels through removal of the homopolymer by solvent extraction. Such membranes are not liquid permeable but have gas-permeability constants about six orders of magnitude higher than that of low-density polyethylene films.     

碱性阴离子交换聚合物膜研究进展

碱性燃料电池(AFCs)是一种直接将化学能转化为电能的发电装置,因其高效、环保等优点,得到了科学界与工业界的广泛关注。阴离子交换聚合物膜作为碱性阴离子交换膜燃料电池的核心组成部分,要求其具备优异的电导率、良好的化学稳定性及力学强度。本文主要从聚合物主链及阳离子官能团的结构与性能之间的关系及调控方式方面,综述了碱性阴离子交换膜的研究进展。     

Ionic Polymerization of α, α -Disubstituted Vinyl Monomers

Alkyl α-chloroacrylates and p-substituted α-methylstyrenes were investigated for the effect of polymerization conditions on tacticity, molecular weight, and distribution, and for the relationship between tacticity, glass temperature, and crystalline properties.     

序列式含芴季铵化聚芳醚砜阴离子交换膜的制备及交联改性

为得到具有高电导率和稳定性的阴离子交换膜,采用两步聚合法合成了含芴的序列式聚芳醚砜,经付克氯甲基化、季铵化及碱化制备了季铵化聚芳醚砜,并以脂肪族二胺(N,N,N′,N′-四甲基丙二胺(TMPDA)及N,N,N′,N′-四甲基己二胺(TMHDA))为交联剂,通过直接交联及后交联法分别制备了2类序列交联型阴离子交换膜.制得的膜材料离子交换容量为1.59~2.12 mmol/g,柔韧结实.与具有相似离子交换容量的非交联膜相比,交联膜的抗溶剂性能、尺寸稳定性、离子电导率等性能均得到了提高.交联膜在高温水中的水解稳定性、强碱性条件下的化学稳定性显著增强.探讨了直接浇铸交联处理及成膜后交联处理2种交联方式对膜性能的影响,结果表明,后交联处理可以有效避免浇膜过程凝胶的形成,而且膜的稳定性相对于未交联膜有大幅度提高.尤其以TMHDA为交联剂的后交联膜的各项性能均优于相应非交联膜,IEC为2.17 mmol/g的PCL-M(H)膜,在30°C时吸水率为99%,膜径向尺寸变化率为15%,电导率为23.8 mS/cm,90°C时电导率达到82 mS/cm,经过4 mol/L的NaOH溶液室温处理240 h后,离子电导率损失为7.6%,100°C水处理24 h后重量损失为5.1%,表现出较好的稳定性.     

Effect of Sulfonation Degree on Performance of Proton Exchange Membranes for Direct Methanol Fuel Cells

A series of proton exchange membranes based on sulfonated polyarylene ether ketones(SPAEKs) was used to study the effect of sulfonation degree on proton conductivity, methanol permeation and performance of direct methanol fuel cells(DMFCs). Dependences of physical characteristics of the membranes, i. e., proton conductivity, water uptake, swelling ratio, methanol permeability and ion exchange capacity(IEC) were systematically studied. Both methanol permeability and proton conductivity of the SPAEK membrane grow rapidly as the increase in sulfonation degree since methanol molecules and protons share the same transfer channel. However,the methanol permeability plays more important role comparing to proton conductivity. As a result, the SPAEK membrane with a medium sulfonation degree(60%) was found to yield the best performance in a DMFC due to the acquirement of balanced conductivity and methanol permeability.     

Dibenzomethanopentacene-Based Polymers of Intrinsic Microporosity for Use in Gas-Separation Membranes

Dibenzomethanopentacene (DBMP) is shown to be a useful structural component for making Polymers of Intrinsic Microporosity (PIMs) with promise for making efficient membranes for gas separations. DBMP-based monomers for PIMs are readily prepared using a Diels–Alder reaction between 2,3-dimethoxyanthracene and norbornadiene as the key synthetic step. Compared to date for the archetypal PIM-1, the incorporation of DBMP simultaneously enhances both gas permeability and the ideal selectivity for one gas over another. Hence, both ideal and mixed gas permeability data for DBMP-rich co-polymers and an amidoxime modified PIM are close to the current Robeson upper bounds, which define the state-of-the-art for the trade-off between permeability and selectivity, for several important gas pairs. Furthermore, long-term studies (over ≈3 years) reveal that the reduction in gas permeabilities on ageing is less for DBMP-containing PIMs relative to that for other high performing PIMs, which is an attractive property for the fabrication of membranes for efficient gas separations.     

自交联型季铵化聚醚砜阴离子交换膜的制备与性能

为改善聚醚砜类阴离子交换膜(QPES)的离子电导率及稳定性,采用3种具有不同长度的脂肪族二胺,即N,N,N',N'-四甲基乙二胺(TMEDA)、N,N,N',N'-四甲基丙二胺(TMPDA)及N,N,N',N'-四甲基己二胺(TMHDA),通过溶液浇铸法制备了一系列自交联型季铵化聚醚砜阴离子交换膜(CQPES).交联膜的抗溶剂性能显著增强,在膜面方向的尺寸稳定性、机械性能、耐水解稳定性及耐碱稳定性均得到了提高,同时离子电导率保持在较高的水平.CQPES膜的性能与二叔胺的结构有较大的关系,以TMHDA为交联剂的CQPES膜离子电导率、耐水解稳定性及耐碱稳定性优于以TMEDA及TMPDA为交联剂的体系.如IEC为1.45 mmol/g的CQPES-H-0.5膜,在30℃时吸水率为43%,尺寸变化率小于10%;在30℃及60℃的水中的电导率分别达到17 m S/cm及64 m S/cm.在稳定性测试方面,CQPES-H-0.5膜经过100℃水处理24 h后重量损失为3.8%,4 mol/L的Na OH溶液室温处理168 h后,离子电导率损失为21%;而相同条件下非交联处理的QPES膜分别为12%及40%.CQPES-H-0.5膜显示了良好的性能,有望在燃料电池系统中得到应用.     

复合型季铵化聚醚砜碱性聚合物电解质膜的制备及性能

利用4,4?-二氟二苯砜(DFDPS)、9,9?-双(4-羟苯基)芴(BHPF)、2,2?-二(4-羟基苯基)丙烷(双酚A)及4,4?-(六氟异丙叉)双酚(双酚AF)为原料,制备了2类具有不同主链刚性的聚醚砜材料.以聚醚砜及其氯甲基化产物按一定质量比采用溶液浇铸法,制备了2类新型共混阴离子交换膜,并避免了成膜过程中的相分离现象.在高分子主链上通过引入双酚芴(BQPAES系列)及双酚A(BQPES系列)结构调整主链的刚性,探讨了主链刚性对性能的影响;表征了共混膜的离子交换容量(IEC)、吸水及溶胀特性与离子电导率,并考察了它们的耐水解和耐碱稳定性.结果表明:2种聚合物相容性良好,共混膜质地均一,柔韧透明,吸水率和溶胀率适中,均随着温度的升高逐渐增加、随着聚醚砜含量增加逐渐减小;在90?C时,离子电导率最高达到89 m S/cm.经过沸水处理24 h后,均保持高机械强度,失重率低于5%;经2 mol/L的Na OH溶液30?C处理168~240 h后离子电导率仍可保持65%~80%.由于含双酚芴结构的高分子主链具有更高的刚性,在类似IEC条件下,BQPAES膜显示了比BQPES膜更好的尺寸稳定性和化学稳定性,同时维持了较高的电导率水平.由此表明,复合处理及适度提高高分子主链的刚性,有利于提高膜的性能.     

Direct Synthesis of Telechelic Polyethylene by Selective Insertion Polymerization

A single‐step route to telechelic polyethylene (PE) is enabled by selective insertion polymerization. Pd^II‐catalyzed copolymerization of ethylene and 2‐vinylfuran (VF) generates α,ω‐di‐furan telechelic polyethylene. Orthogonally reactive exclusively in‐chain anhydride groups are formed by terpolymerization with carbic anhydride. Combined experimental and theoretical DFT studies reveal the key for this direct approach to telechelics to be a match of the comonomers’ different electronics and bulk. Identified essential features of the comonomer are that it is an electron‐rich olefin that forms an insertion product stabilized by an additional interaction, namely a π–η³ interaction for the case of VF.     

烯类单体在室温离子液体中的自由基聚合反应研究进展

介绍了室温离子液体在烯类单体自由基聚合反应中的主要应用,结合国内外研究现状和作者实际工作中的体会,提出了对今后发展趋势的看法。     

Single Solution-Phase Synthesis of Charged Covalent Organic Framework Nanosheets with High Volume Yield

Covalent organic framework nanosheets (COF-NSs) are emerging building blocks for functional materials, and their scalable fabrication is highly desirable. Current synthetic methods suffer from low volume yields resulting from confined on-surface/at-interface growth space and complex multiple-phase synthesis systems. Herein, we report the synthesis of charged COF-NSs in open space using a single-phase organic solution system, achieving magnitudes higher volume yields of up to 18.7 mg mL⁻¹. Charge-induced electrostatic repulsion forces enable in-plane anisotropic secondary growth from initial discrete and disordered polymers into large and crystalline COF-NSs. The charged COF-NS colloidal suspensions are cast into thin and compact proton exchange membranes (PEMs) with lamellar morphology and oriented crystallinity, displaying outstanding proton conductivity, negligible dimensional swelling, and good H₂/O₂ fuel cell performance.     

Rapid Formation of Non-canonical Phospholipid Membranes by Chemoselective Amide-Forming Ligations with Hydroxylamines**

There has been increasing interest in methods to generate synthetic lipid membranes as key constituents of artificial cells or to develop new tools for remodeling membranes in living cells. However, the biosynthesis of phospholipids involves elaborate enzymatic pathways that are challenging to reconstitute in vitro. An alternative approach is to use chemical reactions to non-enzymatically generate natural or non-canonical phospholipids de novo. Previous reports have shown that synthetic lipid membranes can be formed in situ using various ligation chemistries, but these methods lack biocompatibility and/or suffer from slow kinetics at physiological pH. Thus, it would be valuable to develop chemoselective strategies for synthesizing phospholipids from water-soluble precursors that are compatible with synthetic or living cells Here, we demonstrate that amide-forming ligations between lipid precursors bearing hydroxylamines and α-ketoacids (KAs) or potassium acyltrifluoroborates (KATs) can be used to prepare non-canonical phospholipids at physiological pH conditions. The generated amide-linked phospholipids spontaneously self-assemble into cell-like micron-sized vesicles similar to natural phospholipid membranes. We show that lipid synthesis using KAT ligation proceeds extremely rapidly, and the high selectivity and biocompatibility of the approach facilitates the in situ synthesis of phospholipids and associated membranes in living cells.     

有机-无机复合质子交换膜的制备与界面特性

有机-无机复合质子交换膜的开发是燃料电池用质子交换膜的一个重要研究方向,本文综述了有机-无机复合质子交换膜的制备方法,分析了两相之间的界面特性,并对这种复合膜的研究前景进行了展望.     

含有POSS的复合型质子交换膜的制备及性能

本文以一种具有含萘结构的磺酸化聚芳醚酮作为主体材料, 采用具有相似化学结构的含萘、 醚和酮结构的聚甲亚胺作为增强组分, 通过溶胶-凝胶的方法在复合膜中引入提高质子传输能力的酸功能化聚倍半硅氧烷(POSS-SO3H), 制备新型的三元复合型质子交换膜, 并对其微结构和性能进行了研究.     

侧链磺化聚芳醚质子交换膜的研究进展

燃料电池是以氢气、甲醇等作为燃料的一种新型能量转化装置,其中质子交换膜燃料电池（Proton Exchange Membrane Fuel Cell, PEMFC）凭借其能量功率高、启动速度快和使用寿命长等优点已经在移动电源、潜艇和电动汽车等领域得到了广泛应用。质子交换膜（Proton Exchange Membrane, PEM）对PEMFC的性能影响最大,高效的PEMFC需要PEM具有高的质子电导率、良好的热稳定性和机械性能、低燃料渗透率以及优异的物理化学稳定性等。目前市面上多数使用的均是具有优异质子电导率的Nafion系列膜,但其存在制备困难、成本昂贵、质子电导率严重依赖湿度等缺点,在一定程度上限制了其发展。为了让PEM有更多的选择,科学家一直专注于使用新材料替代Nafion膜。近年来,科学家们模拟Nafion结构,通过合成各种侧链含磺酸基团的聚芳醚结构,使得亲水基团磺酸基和疏水基团之间形成微相分离结构,从而获得了一系列具有优异综合性能的PEM。本文将重点对侧链烷基磺化型、侧链磺化嵌段型、侧链局部密集磺化型、侧链磺化交联型和侧链磺化复合型这几种常见策略的合成方法及性能进行了综述,最后展望了侧链磺化聚芳醚在PEM领域的优势及发展前景。     

Anion Exchange Membranes Based on Chloromethylation of Fluorinated Poly(arylene ether)s

This report details the properties of fluorine-containing anion exchange membranes(AEMs) synthesized by chloromethylation and quaternization of fluorinated poly(arylene ether)s(FPAEs) based on decafluorobiphenyl and bisphenol A. Meanwhile, we compared their properties with those of their non-fluorinated counterparts, Udel-based AEMs. The reactivity of the chloromethylation of fluorinated poly(arylene ether)s was lowered by the strong electron-withdrawing group, per-fluorinated biphenyl residue. Therefore higher temperature, more chloromethylation reagent, and longer reaction time were needed in the chloromethylation of FPAEs. Because of the hydrophobicity of fluorine, the swelling of FPAEs was depressed. In the FPAE-based AEMs, the water uptake of FPAE-1 membrane(F-1) was just 30%. There is a strong correlation between water uptake and conductivity for both Udel- and FPAE-based AEMs. Among all the membranes, the water uptake and the conductivity of FPAE-3 membrane(F-3) could reach up to 100% and 13.47 mS/cm respectively at 30 ℃. The mechanical properties of FPAE-based AEMs at room temperature were worse than those of Udel-based ones because of the weak intermolecular interaction caused by the low polarizability of fluorine. However, their high temperature mechanical properties are better, which can be explained in terms of low swelling.     

碱性直接甲醇燃料电池含氟阴离子交换膜的制备及性能研究

以甲基丙烯酸二甲基氨基乙酯和甲基丙烯酸三氟乙酯为单体,经过自由基聚合反应、成膜和碱化3个步骤制备氢氧型的DMAEMA/TFMA聚合物阴离子交换膜,系统表征该聚合物膜的结构和性能.结果表明:室温下其电导率可达10-2 S.cm-1;该膜的甲醇渗透系数低于10-7 cm2.s-1;以该膜组装的单电池在室温下的最大功率密度为43.2 mW/cm2,在燃料电池中有良好的应用前景.     

局部密集交联含氟聚芳醚阴离子交换膜的制备与性能

为开发同时具有阴离子传导率高、钒离子渗透率低、机械性能和化学稳定性优异的阴离子交换膜(AEM),本文以逐步缩聚法合成了含叔胺基的含氟聚芳醚(FPAE),然后以十溴丙基柱[5]芳烃(P5Br)作为交联剂,通过P5Br上的溴烷基与FPAE上的叔胺基之间的亲核取代反应进行交联,最后用碘甲烷将剩余叔胺基季铵化,制得一系列局部密集交联含氟聚芳醚阴离子交换膜QAFPAE-P5Br-x.研究结果表明,所有膜在极性非质子溶剂中都具有较高的凝胶含量,证明已形成高效交联结构.随着交联剂含量从0.5%增加到5%,膜的吸水率、溶胀率、阴离子传导率和VO2+透过率逐渐降低,而离子选择性、拉伸强度、面电阻和氧化稳定性逐渐增加.交联剂含量为1%的QAFPAE-P5Br-1%膜同时具有较低的面电阻和VO²⁺透过率,综合性能优异.以QAFPAE-P5Br-1%组装的全钒液流电池(VRFB)在80 mA·cm^?2的电流密度下具有86.5%的能量效率,比以Nafion 212组装的VRFB高出7.7%.另外,以QAFPAE-P5Br-1%组装的VRFB还具有优异的循环稳定性、放电容量保持率和抗自放电性能.可见,局部密集交联是一种提高VRFB用AEM综合性能的有效方法.