基于阳离子交换基团的阴离子交换膜研究进展

近年来,阴离子交换膜燃料电池的发展受到了广泛关注。 开发具有碱稳定性能优异、电导率高的阴离子交换膜材料成为了研究的热点。 阴离子交换膜(AEM)主要由聚合物骨架和阳离子基团组成,除了聚合物骨架结构,离子交换基团是影响膜碱稳定性和电导率的重要因素,因此,设计离子基团是提高膜性能的重要手段之一。 本文综述了近年来功能基团分别为季铵、胍基、咪唑鎓盐、季鏻、金属配合物、N-螺环季铵盐、哌啶和吡咯等阳离子交换基团的AEM的研究进展,其中包括不同种类阳离子交换基团的AEM的结构,碱稳定性能和OH^-电导率,同时对于含有阳离子交换基团的AEM的结构设计进行了分析和展望。     

1,4-双(二苯基膦)丁烷交联的季膦化聚芳醚酮阴离子交换膜

以1,4-双(二苯基膦)丁烷为交联剂,以具有四甲基联苯结构的聚芳醚酮为基体材料,分别制备了刚性三苯基膦和柔性三丁基膦修饰的阴离子交联膜材料.交联剂在交联结构形成的过程中转变成季膦盐,在提高膜材料机械稳定性的同时保持离子交换功能基团的含量.研究了2种阴离子交换膜的尺寸稳定性、电导率、机械性能及耐碱稳定性等.研究结果表明,当交联度为20%时,三苯基膦与三丁基膦修饰的阴离子交换膜的拉伸强度分别由未交联时的27和18 MPa提高到45和30 MPa;交联的膜材料在60℃的3 mol/L KOH溶液中浸泡120 h后,三苯基膦修饰的阴离子交换膜的电导率保留率为81%,三丁基膦修饰的阴离子交换膜的电导率保留率为69%,膜的耐碱稳定性均较未交联时有明显提高.交联度相同时,三苯基膦修饰的阴离子交换膜表现出更高的拉伸强度和更好的耐碱稳定性.     

高性能氢化星型聚(苯乙烯-b-丁二烯-b-苯乙烯)嵌段共聚物阴离子交换膜的制备、结构与性能

利用常压催化加氢法合成氢化星型聚(苯乙烯-b-丁二烯-b-苯乙烯)嵌段共聚物(HSBS),依次通过氯甲基化、季铵化和碱化反应,制备两种综合性能良好的碱性阴离子交换膜(AEMs),HSBS4303-OH和HSBS4402-OH(二者制备原料中苯乙烯质量分数分别为30%和40%)。 采用傅里叶变换红外光谱(FTIR)对AEMs的结构和制备过程进行表征,并对膜的离子电导率、吸水率、溶胀度、机械性能、微相结构和耐碱稳定性等进行系统地研究。 结果表明,HSBS在90 ℃左右出现了对应于结晶结构的特征熔融峰,相较于SBS,其机械性能及尺寸稳定性显著提高。 两种AEMs中,HSBS4402-OH的性能最佳,该膜的离子交换容量为1.99 mmol/g,30 ℃时的吸水率和溶胀度分别为27.65%和5.12%,80 ℃下的离子电导率高达86.8 mS/cm。 在60 ℃下,采用2 mol/L NaOH溶液浸泡432 h后,该膜的离子电导率损失仅为8.3%。 显而易见,本文方法能为碱性阴离子交换膜燃料电池提供很有前途的AEMs。     

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。     

阳离子可聚合表面活性剂的研究进展

可聚合表面活性剂含有可聚合基团,以牢固的共价键键合到聚合物粒子上,成为聚合物的一部分,有效避免了表面活性剂的解吸及其在乳胶膜中的迁移,减少了乳胶膜表面的亲水基团,可以克服传统表面活性剂的许多弊端。阳离子可聚合表面活性剂主要为季铵盐,其容易吸附于一般固体表面,其水溶液一般有优异的杀菌性。本文综述阳离子可聚合表面活性剂,根据不同方式对其进行分类,分别介绍聚合基团不同的阳离子可聚合表面活性剂的合成和应用现状,并对其应用前景作了展望。     

一类新内酯冠醚的中红外光谱

内酯冠醚化合物的红外光谱研究报道很少,特别是随醚环的扩大和醚环骨架上不同取代基的引入所引起的中红外光谱的变化尚缺乏研究。本文在内酯冠醚环骨架中引入不同基团,通过中红外光谱研究了空间效应、电子因素对酯羰键、酯碳氧键和醚氧键影响。     

后官能化工艺制备侧链离子结构的部分氟化阴离子交换膜

以十氟联苯、双酚A低温聚合制备可高温官能化的聚合物主链,以3,5-二甲基苯酚为功能侧链,采用后官能化工艺制备了系列不同离子交换容量(IEC)值的含侧链苄基季铵基团的部分氟化阴离子交换膜.用GPC、1H-NMR、19F-NMR、IR、SASX等表征了膜的分子结构及聚集态结构,并且测试了膜的各种性能.结果表明,该系列部分氟化阴离子交换膜的分子主链线性好,官能度可控,具有明显的微相分离结构.部分氟化结构和微相分离的侧链离子结构极大的改善了膜的吸水溶胀性、电导率和化学稳定性.QFPAE-95膜具有最高的氢氧根离子电导率和适度吸水溶胀性,80oC时离子电导率和溶胀比分别达到108.6 m S cm-1和42.6%.QFPAE-55具有最大的拉伸强度,达到21.01 MPa.该系列膜还具有出色的碱稳定性,QFPAE-55膜在1 mol/L Na OH溶液中于60oC下浸泡20天后,其电导率和IEC值分别保持为原膜的82.3%和84.2%,有望作为新型阴离子交换膜并应用于碱性膜燃料电池.     

新型双功能交联型阴离子交换膜的制备与性能

以2-甲基咪唑为原料合成2种离子液体前驱体1-烯丙基-2-甲基咪唑和1-丁基-2-甲基咪唑,以苯乙烯(St)和对氯甲基苯乙烯(VBC)为原料制备聚离子液体主链p(St-co-VBC),2种离子液体前驱体与聚离子液体主链发生季铵化反应铸膜,制备了交联结构和梳型侧链结构型阴离子交换膜(AEMs).通过傅里叶红外光谱、扫描电子显微镜和热重分析等考察了阴离子交换膜的结构、微观形貌、氢氧根离子传导率、热稳定性及碱性稳定性等性能.结果表明,AEMs含水率为36.7%~93.4%,离子交换容量为1.61~2.16 mmol/g,80℃时,p(St-co-VBC)-3型AEMs氢氧根离子传导率高达68.4 mS/cm,在1 mol/L NaOH溶液中碱性浸泡240 h后,氢氧根离子传导率仍高达52.2 mS/cm,具备良好的碱性稳定性.     

结晶型聚苯乙烯/氢化聚(苯乙烯-丁二烯-苯乙烯)阴离子交换膜的制备、结构及性能

以低数均相对分子质量均聚聚苯乙烯(hPS)和氢化聚(苯乙烯-丁二烯-苯乙烯)(HSBS)为原材料,经氯甲基化、季胺化和碱化步骤制备以聚丁二烯加氢得到的结晶相为支撑结构的复合型阴离子交换膜(AEMs),并通过hPS用量调节复合膜的组成、结构及性能。随hPS用量增加,拉伸强度有所降低,杨氏模量由14.68 MPa大幅提升至69.35 MPa,吸水率从17.9%增加到54.3%,而溶胀度仅从4.1%增加到10.2%,借助HSBS结晶结构的支撑,体系的力学性能及尺寸稳定性优于多数聚(苯乙烯-(乙烯-丁二烯)-苯乙烯)(SEBS)基AEMs;同时,AEMs结晶微区之间的距离增大,离子传输通道拓宽,离子交换容量值从0.82 mmol/g增大至1.94 mmol/g,耐碱稳定性增强;然而,由于hPS在HSBS中的相容性受HSBS中聚苯乙烯(PS)含量的制约,AEMs的离子电导率值随hPS含量增加呈现出先升后降的变化趋势,其中,氯甲基化HSBS与氯甲基化hPS以质量比8∶2共混制备的AEMs具有最好的离子传输性能,在80℃时离子电导率高达101.3 mS/cm,远高于PS含量相同的SEBS体系,在70...     

光敏自组装多层膜用于向列型液晶光控取向的研究

合成了含有光敏基团、双端为季铵阳离子的有机铵盐.将这种季铵盐与聚乙烯基苯磺酸钠用LBL(Layer-by-layer)方法组装成多层分子沉积膜,紫外光谱证明,这个过程为逐层、均匀沉积过程.在偏振紫外光照射下,多层膜中和光矢量方向匹配的光敏基团发生[2+2]环加成反应,形成表面张力各向异性膜.用该薄膜作向列相液晶的取向膜制成反平行液晶器件,在偏光显微镜下观察,发现取得均一、稳定的取向效果.     

Cationic Metallo‐Polyelectrolytes for Robust Alkaline Anion‐Exchange Membranes

Chemically inert, mechanically tough, cationic metallo‐polyelectrolytes were conceptualized and designed as durable anion‐exchange membranes (AEMs). Ring‐opening metathesis polymerization (ROMP) of cobaltocenium‐containing cyclooctene with triazole as the only linker group, followed by backbone hydrogenation, led to a new class of AEMs with a polyethylene‐like framework and alkaline‐stable cobaltocenium cation for ion transport. These AEMs exhibited excellent thermal, chemical and mechanical stability, as well as high ion conductivity.     

Highly Conductive Anion‐Exchange Membranes from Microporous Tröger's Base Polymers

The development of polymeric anion‐exchange membranes (AEMs) combining high ion conductivity and long‐term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V‐shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion‐exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm^?1 is obtained at a relatively a low ion‐exchange capacity of 0.82 mmol g^?1 under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport.     

Direct Insertion Polymerization of Ionic Monomers: Rapid Production of Anion Exchange Membranes

The limited number of methods to directly polymerize ionic monomers currently hinders rapid diversification and production of ionic polymeric materials, namely anion exchange membranes (AEMs) which are essential components in emerging alkaline fuel cell and electrolyzer technologies. Herein, we report a direct coordination-insertion polymerization of cationic monomers, providing the first direct synthesis of aliphatic polymers with high ion incorporations and allowing facile access to a broad range of materials. We demonstrate the utility of this method by rapidly generating a library of solution processable ionic polymers for use as AEMs. We investigate these materials to study the influence of cation identity on hydroxide conductivity and stability. We found that AEMs with piperidinium cations exhibited the highest performance, with high alkaline stability, hydroxide conductivity of 87 mS cm⁻¹ at 80 °C, and a peak power density of 730 mW cm⁻² when integrated into a fuel cell device.     

Benzimidazolium functionalized polysulfone-based anion exchange membranes with improved alkaline stability

The stability of anion exchange membranes(AEMs) is an important feature of alkaline exchange membrane fuel cells(AEMFCs), which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L~(-1) KOH solution at 80 °C for 336 h. Furthermore, the density functional theory(DFT) study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO) energies of the different 1,2-dimethylbenzimidazolium groups.     

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.     

Chloromethylation and Quaternization of Poly(aryl ether ketone sulfone)s with Clustered Electron-rich Phenyl Groups for Anion Exchange Membranes

Ion segregation is critically important for achieving high ion conductivity for anion exchange membranes(AEMs).Herein,a new bisphenol monomer bearing ten electron-rich phenyl groups was designed and polymerized with various amounts of electron-deficient 4,4′-dihydroxydiphenylsulfone and 4,4′-difluorobenzophenone to yield dense and selective reaction sites for chloromethylation and quaternization.As the most challenging step,chloromethylation was optimized by tuning the reaction temperature,reaction time,and reactant ratios.Ion exchange capacity,water uptake,anion conductivity,mechanical stability,and alkaline stability of the resulting AEMs were characterized in detail.It is found that chloromethylation reaction needed to be carried out at low equivalent of chloromethylation agents to avoid undesirable crosslinking.The QA-PAEKS-20 sample with an IEC of 1.19 mmol·g^-1 exhibited a Cl^–conductivity of 11.2 mS·cm^-1 and a water uptake of 30.2%at80°C,which are promising for AEM applications.     

Elastic and durable multi-cation-crosslinked anion exchange membrane based on poly(styrene-b-(ethylene-co-butylene)-b-styrene)

Anion exchange membranes (AEMs), as the core component of the new generation anion exchange membrane fuel cells (AEMFCs), directly determine the performance and the lifetime of this energy conversion device. Here, AEMs with pendant multiple quaternary ammonium anchored onto the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) backbone are synthesized. The comb-shaped copolymer SEBS-C16 is synthesized with N,N-dimethyl-1-hexadecylamine and chloromethylated SEBS to improve solubility, then the multi-cation crosslinker is prepared and grafted on the above backbone to fabricate a series of flexible multi-cation crosslinked SEBS-based AEMs (SEBS-C16-xC4, where x% is the ratio of the crosslinker to polystyrene block) with practical properties. The obtained SEBS-C16-20C4 membrane exhibits a microphase separated morphology with an interdomain spacing of 18.87 nm. Benefited from the ion channels, SEBS-C16-20C4 shows high conductivity of 77.78 mS/cm at 80°C. Additionally, the prepared SEBS-C16-20C4 membrane with ion exchange capacity of 2.35 mmol/g also exhibits enhanced alkaline stability (5.87% hydroxide conductivity decrease in 2 M NaOH solution at 80°C after 1,700 hr) and improved mechanical properties, compared with the non-crosslinked SEBS-C16 sample. Furthermore, AEMFC single cell performance is evaluated with the SEBS-C16-20C4 membrane, and a maximum power density of 182 mW/cm² is achieved at 80°C under H₂/O₂ conditions.     

Improving the conductivity and dimensional stability of anion exchange membranes by grafting of quaternized dendrons

High conductivity is critical for the practical applications of anion exchange membranes (AEMs) in fuel cells. In this study, a new strategy for enhanced conductivity and dimensional stability of AEMs by incorporating quaternized dendrons is proposed. Thanks to the introduced quaternized dendrons, distinct nanoscale phase separation and well-connected ion conductive channels are formed in the as-prepared membranes (PPO-QG-x). As a result, PPO-QG-x AEMs achieve high hydroxide conductivities up to 65.5 mS cm⁻¹ at 20 °C and 121.5 mS cm⁻¹ at 80 °C (IEC = 1.95 mmol g⁻¹), while possessing good dimensional stability. Meanwhile, PPO-QG-x AEMs show good alkaline stability with the maximum loss in conductivity of 15.1% after treated in 2 M NaOH at 80 °C for 960 h. In addition, the single-cell assembled with PPO-QG-12 membrane exhibit a peak power density of 249.4 mW cm⁻² at 60 °C. Overall, this work provides a new insight to achieve high conductivity of AEMs.     

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.