磁控溅射法制备CeO_2/PTFE/Nafion复合膜及性能研究

采用磁控溅射法在聚四氟乙烯(PTFE)微孔膜表面溅射CeO_2,制备了CeO_2/PTFE复合膜.利用接触角、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和拉伸强度等对复合膜的亲水性、元素组成、形貌和机械强度进行测试,研究了溅射时间和溅射功率对膜性能的影响.结果表明,在溅射功率为40 W,溅射时间为120 s时,CeO_2/PTFE复合膜亲水性和拉伸强度都相对较好.在CeO_2/PTFE复合膜上浇铸Nafion树脂,制备的CeO_2/PTFE/Nafion复合膜含水率达到30%,离子电导率达到0.071 S/cm.     

质子交换膜燃料电池Nafion/PTFE复合膜的研究

在聚四氟乙烯(PTFE)多孔膜内浸入Nafion树脂,制成Nafion/PTFE复合膜用于质子交换膜燃料电池(PEMFC).该复合膜的Nafion含量在50%左右,在干态和湿态时的拉伸强度及水化/脱水过程中,其尺寸稳定性比Nafion均有所提高.在80 ℃,H2/O2压力为0.2/0.2 MPa条件下,用25 μm厚复合膜组装的电池性能优于Nafion117膜组装电池的性能.测量了复合膜的O2渗透率和含水量并与Nafion膜的性能作了比较.     

含全氟联苯结构的磺化聚二氮杂萘酮醚氧膦质子交换膜的制备与性能

将全氟联苯、 二(4-氟苯基)苯基氧膦与4-(4′-羟基)苯基-2,3-二氮杂萘酮共聚, 合成了含全氟联苯结构的聚二氮杂萘酮醚氧膦, 再经磺化反应, 制备了含全氟联苯结构的磺化聚二氮杂萘酮醚氧膦(sPEPOF-x, x为含氟重复单元的摩尔分数)质子交换膜. 由于强疏水全氟联苯结构促进了聚合物膜的亲水/疏水微相分离, 提高了质子电导率, 降低了溶胀率, sPEPOF质子交换膜表现出优良的综合性能. 在80 ℃下, sPEPOF-25质子交换膜的溶胀率仅为10%, 约为Nafion 117的一半, 而其电导率为0.099 S/cm, 约为Nafion 117的1.2倍, 且耐氧化稳定性好, 热稳定性高, 具有潜在的应用前景.     

四乙基氢氧化铵改性聚偏氟乙烯接枝聚丙烯酸油水分离膜的制备

使用四乙基氢氧化铵(TEAH)液相本体改性聚偏氟乙烯(PVDF), 以过氧化苯甲酰(BPO)为引发剂, 将丙烯酸(AA)接枝到改性PVDF骨架上, 合成了聚偏氟乙烯接枝聚丙烯酸(PVDF-g-PAA)共聚物, 通过浸没沉淀法制备了PVDF-g-PAA亲水性油水分离膜. 通过傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和过滤试验分析了膜的结构和分离性能. 研究了不同接枝条件对PVDF-g-PAA膜接枝率的影响. 同时, 通过膜接枝率与膜表面接触角的关系确定最佳接枝条件. 结果表明, TEAH使PVDF脱去HF产生碳碳双键且PAA接枝到改性的PVDF骨架上, 膜内外孔隙分布均匀; PVDF-g-PAA膜的接触角随着接枝率的提高而降低. 接枝单体AA含量为45%, 接枝温度为85 ℃, 接枝4 h制备的PVDF-g-PAA膜的接枝率为20.1%, 孔隙度为65.3%, 平均孔径为78.0 nm, 接触角为57.5°, 且在60 s内接触角降至14.3°; 纯水通量提高到571.33 L/(m²·h), 截留率和水通量恢复率分别达到94.3%和88.7%, 且通量衰减率仅为9.8%. 与纯PVDF膜相比, PVDF-g-PAA膜的分离性能显著提高.     

高亲水性聚四氟乙烯微粉的制备及其性能研究

通过预辐射接枝方法在聚四氟乙烯(PTFE)微粉上成功接枝丙烯酸(AAc)和2-丙烯酰胺-2-甲基丙磺酸(AMPS),制备了高亲水性的PTFE微粉.采用红外光谱(FTIR)、X射线光电子能谱(XPS)和接触角(CA)测试表征了改性PTFE微粉的化学结构和亲水性变化;采用扫描电子显微镜(SEM)观察改性PTFE微粉表面形貌;采用电泳法测试了改性PTFE微粉的zeta电位;通过热重分析(TGA)测试了辐射接枝对PTFE微粉热稳定性的影响.结果表明,改性PTFE微粉亲水性和分散稳定性随着接枝率的增加而增强;在单体浓度为20%,AAc与AMPS之比为2且反应温度为70℃时接枝率达到26.6%,此时改性样品PTFE-g-P(AAc-co-AMPS)在水溶液中的分散稳定性效果较好,并能够长期稳定存在.水接触角由改性前的148.8°下降到改性后的30.2°,对应的zeta电位从-4.3 m V降为-83.4 m V.     

磺化双酚芴型聚醚醚酮质子交换膜的制备及其在钒流电池中的应用

以双酚芴为结构单元合成双酚型聚醚醚酮聚合物,聚醚醚酮经浓硫酸磺化在双酚芴结构单元中引入磺化基团制备出聚醚醚酮质子交换膜(SF-PEEK)。 用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(¹H NMR)、热重分析(TG)、原子力显微镜(AFM)和扫描电子显微镜(SEM)等方法对聚醚醚酮质子交换膜的结构进行表征。 结果表明,磺酸基团被成功地在聚醚醚酮侧基上,SF-PEEK膜具有明显的亲水疏水微相分离形貌,磺酸基团相互聚集成形成离子通道。 SF-PEEK膜离子交换容量(IEC)达到1.97 mmol/g时,其电导率达到4.15×10^-2 S/cm,略低于Nafion117膜的5.67×10^-2 S/cm,但其钒离子渗透率仅为Nafion117膜的20.1%,表现出极好的离子选择性。 在钒流电池测试中,SF-PEEK膜在不同电流密度下库伦效率均高于Nafion117膜,其中IEC为1.97 mmol/g的SF80-PEEK608(80为SF的物质的量分数,608为60 ℃反应8 h)库伦效率在电流密度为40 mA/cm²时达到最大值80.9%,高于Nafion117膜的78.8%。 在自放电测试中,以SF80-PEEK608膜组装的电池的自放电时间为90 h,高于Nafion117膜的57 h。     

SPES/SiO_2杂化纳米纤维复合质子交换膜的制备与性能

提出了一种利用杂化纳米纤维来制备高性能质子交换膜的方法,首先采用溶液喷射纺丝技术纺制了SPES/Si O2杂化纳米纤维,再通过溶液浸渍法制备了SPES/Si O2/Nafion复合质子交换膜,并研究了其热稳定性、吸水性能、溶胀性能、质子传导性能以及甲醇渗透性能等.结果表明,杂化纳米纤维的引入明显改善了Nafion膜的热性能、尺寸稳定性,并大大提高了其质子传导性能.TG数据表明复合膜的热稳定性相比于Nafion膜得到了极大改善.复合膜溶胀率均比Nafion膜的小,SPES/Si O2/Nafion-5,SPES/Si O2/Nafion-15和SPES/Si O2/Nafion-25在80℃溶胀率仅为14.9%,15.84%和17.2%,但是复合膜的溶胀率随着Si O2含量的增加而增大.复合膜电导率随Si O2含量的增加呈先增大后减小的规律,Si O2含量为15%的复合膜在80℃、100%湿度条件下,质子导电率可达到0.154 S/cm.其阻醇性能也得到了极大改善,Si O2含量为25%的复合膜相比于Nafion膜其甲醇渗透率降低了55.3%.因此SPES/Si O2杂化纳米纤维复合质子交换膜可以作为一种新型质子交换膜应用于燃料电池中.     

PTFE辐射接枝对苯乙烯基三甲氧基硅烷制备质子交换膜

采用聚四氟乙烯(PTFE)膜室温下共辐射接枝单体p-苯乙烯基三甲氧基硅烷(StSi),之后经磺化和水解缩聚制备了含有亲水性的—Si—O—Si—交联结构和Si—OH基团的质子交换膜.研究了溶剂、吸收剂量、吸收剂量率以及单体浓度等参数对接枝率的影响,并对质子交换膜的离子交换容量(IEC)、吸水性、尺寸稳定性及电导率等性能进行了分析.结果表明,实验条件下接枝率随吸收剂量和单体浓度增加而增加,采用3mol·L-1的单体浓度减少均聚物;吸收剂量率为10～43Gy·min-1时,接枝率随剂量率变化不明显;以甲苯做溶剂可获得较高接枝率并保持膜的机械强度;IEC值、吸水性和电导率随接枝率增加而增大,是—SO3H、—Si—O—Si—交联结构和Si—OH基团共同作用的结果.接枝率72.5%时膜的IEC值为1.53mmol·g-1,高于Nafion117(0.89mmol·g-1),90℃吸水率为63%,尺寸稳定(优于Nafion117),质子电导率达1.5×10-2S·cm-1,获得了低于Nafion117的甲醇透过性,接枝率50.1%时甲醇透过系数0.82×10-6cm2·s-1.     

高性能磺化聚(苯-酰亚胺)质子传输膜的合成及表征

本文首次利用Ni11催化偶联合成了一系列的磺化聚苯和聚(苯-酰亚胺)质子传输膜材料,在聚合物中引入酰亚胺基团,提高了聚合物的成膜性和机械性能.由于SPI(Ⅰ)和SPI(Ⅱ)中存在不对称结构的酰亚胺基团,破坏了分子链的堆积,因此得到的膜具有较高的水吸收;尽管SPP具有高的IEC值,但水吸收很低.和Nafion 117(1.7?10-1S/cm,at 80℃)膜相比,磺酸的强酸性和良好的相分离结构导致高的质子导电率(大于2.6?10-1S/cm,at 80℃);尤其是在高温时,SPI(Ⅰ)和SPI(Ⅱ)膜都表现出了很高的质子导电率,可能是由于酰亚胺的不对成结构使得膜在高温时仍能保持大量的水分子以利于质子传输,例如SPI(Ⅰ)-70在80℃的质子导电率为0.687S/cm,相当于相同测试条件下Nafion 117的三倍.同时,-CF3和全芳香结构的引入大大的提高了膜的氧化稳定性,SPI(Ⅰ)膜在Fenton's试剂中完全溶解的时间高达263h;疏水的-CF3基团引入在氨基的邻位,阻止了水分进攻酰亚胺环,因此膜的水解稳定性得到很大的提高.柔性链的引入以及酐的低电子云密度,更大程度的提高了膜的水解稳定性,SPI(Ⅱ)-70在140℃的水中250h仍能保持原有的机械性能,这是目前报道的水解稳定时间最长的膜材料.因此,该膜有望成为一种新型的性能优良的质子传输膜材料在燃料电池中应用.     

磺化聚芳醚砜/磺化聚酰亚胺复合质子交换膜的制备与性能研究

利用溶液浇铸法制备了一系列双磺化型磺化聚芳醚砜/磺化聚酰亚胺(SPAES/SPI)复合质子交换膜.扫描电子显微镜(SEM)结果显示复合膜不存在明显的相分离,表明二者具有很好的相容性.由于SPI的引入,复合膜在甲醇中稳定性较纯SPAES具有大幅的提高,比Nafion112低得多的甲醇吸收率表明了这些复合膜具有比后者更低的甲醇透过率.复合膜显示了与单组分膜相类似的高温分解稳定性,磺酸基团的分解温度达到了290℃以上.复合膜显示出远高于纯SPAES膜的尺寸稳定性能,在130℃高温中200h处理后,所有的复合膜均保持了高的机械性能,而此时纯SPAES膜已经溶解于水中.而且由于两种磺化聚合物间的复合,复合膜维持了较高的IEC水平,显示了较高的质子导电率,在80%相对湿度时的质子导电率与Nafion112相近,而在水中的质子导电率均高于Nafion112.     

Nafion/PTFE and zirconium phosphate modified Nafion/PTFE composite membranes for direct methanol fuel cells

We prepared Nafion/PTFE (NF) and zirconium phosphate (ZrP) hybridized Nafion/PTFE composite membranes (NF–ZrP). NF–ZrP composite membranes were prepared via two processes. One is impregnating sub-μm porous PTFE membrane directly in a Nafion/ZrOCl₂ solution (NF–Zr–d). The other is impregnating sub-μm porous PTFE membrane in a Nafion solution to prepare NF composite membrane, and then the NF membrane was impregnated in a ZrOCl₂ aqueous solution via in situ precipitation method (NF–Zr–I). The ZrOCl₂ inserted in NF composite membranes was then reacted with phosphoric acid to form ZrP and thus NF–ZrP–d and NF–ZrP–I composite membranes were obtained. The direct methanol fuel cell (DMFC) performances of membrane electrode assemblies prepared from Nafion-117, NF, NF–ZrP–d, and NF–ZrP–I composite membranes were investigated. The effects of introducing sub-μm porous PTFE film and ZrP particles into Nafion membranes on the DMFC performance were investigated. The influence of ZrP hybridizing process into NF membranes (the process of preparing NF–ZrP–I is inserting ZrOCl₂ into NF membranes after Nafion is annealed and the process of preparing NF–ZrP–d is mixing ZrOCl₂ into a Nafion solution before Nafion is annealed) on the morphology of NF–ZrP composite membranes and thus on the DMFC performance was also discussed.     

Reinforced and self-humidifying composite membrane for fuel cell applications

A novel preparation method for a composite proton exchange membrane with reinforced strength and self-humidifying property was developed. Using self-assembly method, highly dispersed poly(diallyldimethylammonium chloride) (PDDA) stabilized Pt nanoparticles were mounted onto the pores of poly(tetrafluoroethylene) (PTFE) porous film to serve the self-humidifying purpose. With Pt nanoparticles fixed on the PTFE pores, the potential problem of any short circuit because of the use of metal nanoparticles can be prevented. Pt-PDDA/PTFE substrate in the composite membrane can enhance the mechanical strength of the membrane and distribute self-humidifying layer adjacent to the anode side. Compared with the cells fabricated with conventional Nafion^® and PTFE/Nafion membranes, the performance of the cells with this composite membrane is dramatically improved under dry conditions. Electrochemical impedance spectroscopy technique revealed that these self-humidifying composite membranes could minimize membrane conductivity loss under dry conditions.     

SPES/PWA/SiO_2复合质子交换膜的性能

以磺化聚醚砜(SPES)为基体,以不同比例的SiO2溶胶与磷钨酸(PWA)为掺杂物,制备了一种有望用于直接甲醇燃料电池(DMFC)的新型SPES/PWA/SiO2有机-无机复合膜,并经热失重分析(TGA)、差示扫描量热仪(DSC)、扫描电镜(SEM)-X射线能谱分析(EDX)等对膜的结构和性能进行了表征,探讨了复合膜用作质子交换膜的可能性.结果表明:复合膜较纯SPES膜具有更高的热稳定性、玻璃化转变温度和吸水率;虽然在室温和电池操作温度(80℃)下,复合膜的拉伸强度均低于纯SPES膜,但即使当SiO2含量高达20%(w)时,复合膜的拉伸强度仍高于Nafion112膜的;SEM图片显示SiO2和PWA在膜中分布均匀,这将有利于连续质子传输通道的形成.对于SiO2含量为15%(w),PWA含量为6%(w)的复合膜,其室温质子传导率达到了0.034S·cm-1,与Nafion112膜的相当,但其甲醇渗透率明显降低,仅为商用Nafion112膜的七分之一左右,这表明该复合膜在直接甲醇燃料电池中具有良好的应用前景.     

Poly(tetrafluoroethylene) composite membranes coated with urchin-like polyaniline hiberarchy: Preparation and properties

Spiny polyaniline (PANI) spheres (urchin-like) were coated on a poly(tetrafluoroethylene) (PTFE) membrane via a counter-diffuse interfacial oxidation polymerization of aniline in an aqueous medium. The produced composite membrane has both unexpected superhydrophilicity and conductivity. The microstructure and morphology of the composite membrane were characterized by FTIR, UV-vis, XRD, TGA, and SEM. Effects of reagent concentrations and polymerization time on the membrane morphology and properties were studied systematically. A possible formation mechanism of the urchin-like polyaniline nanospheres on PTFE surface has been briefly discussed. The co-effect of both spherical micelles formed by Nafion and nanofibrous micelles formed by aniline/p-toluenesulfonic acid was considered to be a reason to produce the urchin-like PANI nanospheres. The PTFE/Nafion/PANI composite membrane showed a convertible hydrophilic/hydrophobic feature via adjusting acidity/alkalinity of an aqueous medium and also was able to adsorb heavy metal-ions from the medium.     

Nanophase segregation and water dynamics in the dendrion diblock copolymer formed from the Fréchet polyaryl ethereal dendrimer and linear PTFE

We propose a new material consisting of a dendrion copolymer formed from (a) a water-soluble dendritic polymer and (b) a hydrophobic backbone. Using molecular dynamics simulations techniques, we determine the structure and dynamics of the dendrion formed by second-generation Fréchet polyaryl ethereal dendrimer as the hydrophilic component and linear polytetrafluoroethylene (PTFE) as the hydrophobic polymer, with 5 and 10 wt % of water. We find that this material produces a well-developed nanoscale structure in which water forms a continuous nanophase, making this new family of compounds promising candidates for applications in fuel cell membranes. We find that the water molecules are incorporated into the dendrimer block of the copolymer to form a nanophase-segregated structure. The well-developed nanophase-segregated structures rendered by this material have characteristic dimensions of segregation ( approximately 30 Angstrom) and dendrimer conformational properties that are independent of water content. Calculations of water dynamics and proton transport in these nanophase-segregated structures indicate that the dendrion copolymer membrane with 10 wt % of water content has a water structure and transport properties equivalent to that of the hydrated Nafion membrane with 20 wt % of water content.     

不同EW值的sPTFS/PTFE复合膜性能研究

将两种不同EW值的聚α,β,β＿三氟苯乙烯(sPTFS)树脂浸入到多孔聚四氟乙烯(PTFE)膜的孔中,制成sPTFS/PTFE复合膜用于质子交换膜燃料电池(PEMFC).并对该复合膜的吸水率,电导率,机械强度及其装配的电池性能进行了测试.与其它均质膜相比,复合膜明显降低了吸水率,同时也降低了电导率,增加了机械强度.在电池温度为80℃,H2/O2压力为0.2/0.2MPa条件下,两种复合膜装配电池的性能优于Nofion 115膜.低EW值的复合膜电池性能优于高EW值的电池性能,但电池稳定性相对较差.     

含芴和双酚AF型氮杂萘酮的两亲嵌段聚芳醚砜酮离聚物的合成与性能

采取"二锅二步"的聚合方法以双酚芴、4,4'-二氯二苯砜、双酚AF型二氮杂萘酮、二氟二苯酮磺酸钠为原料制备了含芴-聚芳醚砜憎水链段和双酚AF型二氮杂萘酮-磺化聚芳醚酮亲水链段的两亲嵌段聚芳醚砜酮离聚物,通过调整4种单体的比例以及预聚合、再缩合聚合工艺制备了一系列具有不同链段尺寸的芴-双酚AF型氮杂萘酮-两亲嵌段聚芳醚砜酮离聚物质子交换膜材料.通过黏度测试、傅里叶变换红外光谱(FTIR)、氢谱(1H-NMR)、热失重(TGA)等分析方法,对离聚物的结构和性能进行了表征,用蒸发溶剂法制备了质子交换膜,并考察膜的各种性能.实验结果表明,该系列离聚物的结构可控,热稳定性良好,5 wt%热失重温度均高于250℃;由其制备的质子交换膜具有良好的耐醇性和耐甲醇渗透性能、优异的抗氧化性和水解稳定性、以及适当的质子导电率和吸水率,室温下该系列膜的甲醇渗透率在0.23×10-6～0.28×10-6cm2/s,比Nafion 117具有更好的耐甲醇渗透性能;80℃下该系列膜的质子导电率与30℃时相比呈现倍增趋势,离聚物8e膜的质子导电率在80℃下达到了1.83×10-3S/cm.     

Pt/SiO2 as addition to multilayer SPSU/PTFE composite membrane for fuel cells

A multilayer composite membrane was prepared by reinforcing sulfonated polysulfone (SPSU) with porous polytetrafluoroethylene (PTFE), and adding Pt/SiO₂–Nafion® membranes on both sides of the SPSU/PTFE membrane to self‐humidify and protect the inside membrane. The ex situ Fenton test and open circuit voltage (OCV) accelerated test show that the composite membrane has better stability than the initial membrane because of the protection of the outside Pt/SiO₂–Nafion layers. The composite membrane has similar performance to that of NRE‐212 under the fully humidified condition and better performance than NRE‐212 without humidifying. The self‐humidifying membrane shows great potential for use in low humidifying conditions. Copyright © 2008 John Wiley & Sons, Ltd.