Name: electrophoretic crystallization of ultrathin high-performance metal-organic framework membranes
Uploaded: 2018-08-16T15:00:00.000+00:00
Duration: 7 min 45 s
Description: Watch this Scientific Journal Video about Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes at JoVE.com

我们承认我们的家庭机构, 高等理工 Fédérale 洛桑 (EPFL), 为其慷慨的支持。该项目已从欧洲联盟2020《玛丽居里夫人-居里赠款协定》665667号下的研究和创新项目中获得资金。作者感谢帕斯卡亚历山大 Schouwink 为他的帮助与 XRD。

注意事项: 仔细阅读有关化学品的材料安全数据表 (MSDS)。实验中使用的一些化学物质是有毒的。本方法涉及纳米粒子的合成。因此, 采取适当的预防措施。整个合成过程必须在通风良好的油烟机中进行。
注:表 1列出了 MOF 薄膜合成中所涉及的仪器、化学品和材料的详细情况。
1. 制备金属盐溶液和前体溶胶的连接器溶液
注: 为合成 ZIF-8 膜, 硝酸锌六水合物 [锌 (NO3)2. 6H2O] 用于金属盐和 2-甲基咪唑 (HmIm) 作为链接器。
<ol><li>对于金属盐溶液, 溶解2.75 克锌 (NO3)2. 6H2O 在500毫升水中。</li>
	<li>对于链接器溶液, 在500毫升的水中溶解56.75 克 HmIm, 并连续搅拌直到得到一个清晰的溶液。</li>
</ol>2. 铜电极的制备
<ol><li>切割高纯度铜箔 (99.9% 纯度, 127 µm 厚) 成 4 x 4 厘米件。</li>
	<li>为了便于夹紧切割箔到一套铜鳄鱼夹子, 画一条线在距离 0.5 cm 从正方形箔的边缘之一。</li>
	<li>用圆柱滚子在干净的表面上拼合箔。</li>
	<li>用丙酮浴超声波彻底清洁铜箔15分钟, 其次为15分钟, 异丙醇浴超声波。</li>
	<li>在干净的气氛中烘干铜箔。</li>
</ol>3. 基体附着在电极上 (阴极)
注: 选择合适的基底以存放 MOF 胶片。该方法可应用于氧化铝 (Anodisc、13毫米直径的承载孔直径为0.1 µm), 聚丙烯腈 (PAN, 分子量截止: 100 kDa), 铜箔 (99.9% 纯度, 25 µm 厚), 一种化学气相沉积基石墨烯膜铜箔11, 自制的纳米孔碳膜, 在铜箔上停留12,13,14。
<ol><li>用胶带将所需的基板小心地放置在铜电极的中心。</li>
	<li>用清水冲洗承印物/电极组件, 其次为异丙醇, 再用清水约1分钟。</li>
	<li>将裸铜电极 (4 x 4 厘米) 连接至阳极。然后将基板/电极组件连接至阴极。</li>
	<li>调整两个电极之间的分离, 以1厘米内100毫升玻璃烧杯。</li>
</ol>4. ZIF-8 电影的颁布程序
<ol><li>在100毫升烧杯中混合31.6 克的金属前体溶液和35克配体溶液, 在室温下搅拌三十年代, 形成前驱溶胶。 注: ZIF-8 在这些情况下的诱导时间不到六十年代, 因此, 环保署必须毫不迟延地进行。</li>
	<li>将前体溶胶转移到承载电极的容器中。</li>
	<li>将两个电极浸入电极上的3.5 厘米标记上。 注: 从我们的实验中, 我们观察到, 在3分钟的溶胶老化之前应用电场会导致较小的 ZIF-8 核渗透到多孔基质 (在这个特殊情况下的氧化铝) 的孔隙中, 需要避免。因此, 电场在3分钟后才打开, 当原子核长得有点大时。</li>
	<li>执行环保署的沉积电压为1伏特4分钟。电流应在 2.5-3.5 mA 的范围内。</li>
	<li>在环保署结束时, 慢慢降低烧杯的速度。由于新沉积的原子核与基体之间的附着力较弱, 在处理基体时必须极为小心。</li>
	<li>将干基板转移到显微镜玻璃滑梯上。使用胶带将基板保持到位。</li>
	<li>对于晶体生长, 混合31.6 克的金属盐溶液和35克的链接器解决方案在100毫升烧杯。</li>
	<li>在前体溶液中垂直放置显微玻璃滑块, 并使其在30摄氏度时不受干扰10小时。</li>
	<li>经过10小时的晶体生长, 用清水冲洗基体30分钟, 在干净的气氛中干燥。</li>
</ol>5. ZIF-7 电影的颁布程序
<ol><li>用类似于 ZIF-8 薄膜的一种方法, 在氧化铝支架上合成 ZIF-7 膜, 但有以下区别。</li>
	<li>混合后0.82 克锌 (NO3)2· 6H2O 在30毫升的甲基酰胺 (DMF) 和0.72 克苯丙咪唑在30毫升甲醇为3分钟, 执行环保署1分钟。</li>
	<li>将 ZIF-7 核膜浸泡在含有0.58 克锌 (NO3)2· 6H2O、0.3 克咪唑和30毫升的 DMF 的前体溶胶中, 合成共生矿 ZIF-7 膜, 110 摄氏度。</li>
	<li>冷却溶液后, 将 ZIF-7/AAO 膜浸泡在 DMF 中, 然后将其干燥60摄氏度, 12 小时。</li>
</ol>6. 膜的制备和表征
<ol><li>
膜的制备
	<ol>
<li>为制备密封胶, 完全混合均匀的树脂和硬化剂, 并保持混合物1小时。</li>
		<li>将 ZIF-8/support 膜放在24毫米宽的钢盘上, 中间有5毫米直径的孔。</li>
		<li>首先将环氧树脂沿基板的边缘涂抹, 然后盖上衬底, 除去中心的5毫米直径孔。</li>
		<li>允许环氧干燥过夜。</li>
		<li>使用立体显微镜扫描膜以及已知的参考刻度。</li>
		<li>使用图形软件从扫描图像中计算出膜的外露区域。</li>
	</ol>
</li>
	<li>
气体渗透试验 注: 在实验中, Wicke-卡伦巴赫技术在自制的渗透细胞中进行单组分气体渗透试验。在5% 误差范围内校准了渗透装置中使用的质量流量控制器 (MKS) 和质谱仪。质量流量控制器 (MFC) 调节进给和扫气流速。Ar 被用作将渗透气体带入校准质谱仪 (MS) 的扫气, 用于对渗透浓度进行实时分析。<ol>
<li>将钢盘与膜放在不锈钢渗透细胞中。</li>
		<li>通过将氟橡胶 O 形环放在钢盘的上方和下方, 并固定螺钉, 确保密封的配合。要在合成过程中去除吸附水, 在 h2/Ar 大气中将膜干燥130摄氏度, 直到达到稳定的 h2磁渗透。</li>
		<li>将设置放在烤箱内, 将温度设置为130摄氏度。</li>
		<li>确保进纸和扫描线已预热。</li>
		<li>将进料和扫边上的气体流量设置为30毫升/分钟。</li>
		<li>通过调整 retentate 和渗透侧的针阀, 在饲料和扫边上保持0.1 兆帕的压力。</li>
		<li>建立稳态后, 计算出磁导。</li>
		<li>慢慢冷却烤箱 (约2小时) 到30°c, 并记录的价值, 一旦稳定状态建立。</li>
	</ol>
</li>
</ol>

<ol>
	<li>Knebel, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defibrillation+of+soft+porous+metal-organic+frameworks+with+electric+fields.">Defibrillation of soft porous metal-organic frameworks with electric fields.</a> Science. 358, 347-351 (2017).</li><li>Brown, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfacial+microfluidic+processing+of+metal-organic+framework+hollow+fiber+membranes.">Interfacial microfluidic processing of metal-organic framework hollow fiber membranes.</a> Science. 345, 72-75 (2014).</li><li>Dzubak, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ab+initio+carbon+capture+in+open-site+metal-organic+frameworks.">Ab initio carbon capture in open-site metal-organic frameworks.</a> Nature Chemistry. 4, 810-816 (2012).</li><li>Gascon, J., Kapteijn, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal-organic+framework+membranes-high+potential,+bright+future.">Metal-organic framework membranes-high potential, bright future.</a> Angewandte Chemie International Edition. 49, 1530-1532 (2010).</li><li>Liu, X., Wang, C., Wang, B., Li, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Organic-Dehydration+Membranes+Prepared+from+Zirconium+Metal-Organic+Frameworks.">Novel Organic-Dehydration Membranes Prepared from Zirconium Metal-Organic Frameworks.</a> Advanced Functional Materials. 27, 1-6 (2017).</li><li>Zhang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+selective+NH2-MIL-53(Al)+MOF+membranes+with+high+permeability.">Hydrogen selective NH2-MIL-53(Al) MOF membranes with high permeability.</a> Advanced Functional Materials. 22, 3583-3590 (2012).</li><li>Kwon, H. T., Jeong, H. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+synthesis+of+thin+zeolitic-imidazolate+framework+ZIF-8+membranes+exhibiting+exceptionally+high+propylene/propane+separation.">In situ synthesis of thin zeolitic-imidazolate framework ZIF-8 membranes exhibiting exceptionally high propylene/propane separation.</a> Journal of the American Chemical Society. 135, 10763-10768 (2013).</li><li>Hou, J., Sutrisna, P. D., Zhang, Y., Chen, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+ultrathin,+continuous+metal-organic+framework+membranes+on+flexible+polymer+substrates.">Formation of ultrathin, continuous metal-organic framework membranes on flexible polymer substrates.</a> Angewandte Chemie International Edition. 55, 3947-3951 (2016).</li><li>Barankova, E., Tan, X., Villalobos, L. F., Litwiller, E., Peinemann, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+metal+chelating+porous+polymeric+support:+the+missing+link+for+a+defect-free+metal-organic+framework+composite+membrane.">A metal chelating porous polymeric support: the missing link for a defect-free metal-organic framework composite membrane.</a> Angewandte Chemie International Edition. 56, 2965-2968 (2017).</li><li>He, G., Dakhchoune, M., Zhao, J., Huang, S., Agrawal, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophoretic+Nuclei+Assembly+for+Crystallization+of+High-Performance+Membranes+on+Unmodified+Supports.">Electrophoretic Nuclei Assembly for Crystallization of High-Performance Membranes on Unmodified Supports.</a> Advanced Functional Materials. , (2018).</li><li>Li, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-area+synthesis+of+high-quality+and+uniform+graphene+films+on+copper+foils.">Large-area synthesis of high-quality and uniform graphene films on copper foils.</a> Science. 324, 1312-1314 (2009).</li><li>Rodriguez, A. T., Li, X., Wang, J., Steen, W. A., Fan, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facile+synthesis+of+nanostructured+carbon+through+self-assembly+between+block+copolymers+and+carbohydrates.">Facile synthesis of nanostructured carbon through self-assembly between block copolymers and carbohydrates.</a> Advanced Functional Materials. 17, 2710-2716 (2007).</li><li>Huang, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-area+single-layer+graphene+membranes+by+crack-free+transfer+for+gas+mixture+separation.">Large-area single-layer graphene membranes by crack-free transfer for gas mixture separation.</a> Nature Communications. , (2018).</li><li>Agrawal, K. V., Dakachoune, M., Huang, S., He, G., Dudani, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ultrahigh flux gas-selective nanoporous carbon membrane and manufacturing method thereof. , (2017).</li><li>Liu, J., W&#246;ll, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-supported+metal-organic+framework+thin+films:+fabrication+methods,+applications,+and+challenges.">Surface-supported metal-organic framework thin films: fabrication methods, applications, and challenges.</a> Chemical Society Reviews. 46, 5730-5770 (2017).</li></ol>

作者没有什么可透露的。

对于现有方法15的颁布方法的突出特点是, 颁布方法能够在广泛的多孔和型无孔基板上合成高共生矿、超薄的 MOF 薄膜。避免了任何衬底预处理, 使得这种方法对 MOF 薄膜的合成非常简单。虽然环保署的设备必须用于沉积核膜, 设备是由一个电源, 金属电极和烧杯, 这是相当简单和容易接近。我们认为, 这种简便的制定方法可以扩展到广泛的晶体薄膜的合成。
制定过程很简单, 因为准备协议相对简单。这对于一组在室温下显示快速生长动力学的晶体, 如 MOFs, 尤其如此。整个合成过程可以分解成3个整体步骤: i) 在前体溶胶 (ii) 中设置电极组件, 在预先计算好开始时间 (取决于原子核的大小) 打开电场, 以存放 nuclei 膜和 iii) 将细胞核膜浸泡在前驱溶胶中, 以促进生长和随后的共生。这个过程可以适应一系列的水晶材料。唯一的先决条件是对感应时间、大小、原子核密度和泽塔电位的认识。这些信息可以通过透射电镜和电子衍射和测量泽塔电位来表征细胞核的形貌和结晶度。
为成功合成高质量的 MOF 薄膜, 有三个关键的考虑因素。(i) 电泳沉积应仅在感应时间后进行。为此, 有必要通过光谱学或衍射或显微技术来分析前体溶胶中原子核的演化。(二) 核电泳沉积是一个关键步骤。在这一步骤中, 应谨慎地进行电压和沉积时间的选择。过高或沉积时间过长的电压可能导致厚核膜的沉积, 随后的生长成厚的 MOF 膜会降低膜的整体性能。另一方面, 小的电压会导致一个小的电场, 并可能导致质量较差的薄膜。(iii) 在晶体生长步骤中, 生长时间应足够长, 以确保产生的 MOF 胶片高度共生矿。如果在获得高共生矿膜之前, 前体溶胶中的养分耗尽, 可以使用新的前驱溶胶。
图 1a显示了与铜电极 (阴极) 粘合的基板。图 1b说明了阴极的平行装配和连接到电源的阳极。电极浸泡在前体凝胶中, 用于合成 MOF 薄膜 (图 1c)。在4分钟的核环保署, 一个紧凑, 100 纳米厚的 ZIF-8 核膜形成的氧化铝支持, 如图 2a和2b所示。该薄膜由 ZIF-8 核组成, 平均大小约为40纳米。该薄膜的 XRD (图 1c) 验证了细胞核膜是由 ZIF-8 晶体制成的。
在 10 h (图 3a - 3c) 的合成溶胶中离开细胞核膜后, 在氧化铝支架上生成了一层厚度为 500 nm 的紧凑型高共生矿 ZIF-8 薄膜。更薄的 ZIF-8 薄膜 (360 nm) 是在多孔 PAN 支持 (图 3d - 3f) 上生成的。不同的膜厚度可以归结为一个略有不同的异质核密度, 由于不同的孔隙大小的氧化铝和多孔 PAN 支持。
ZIF-8 膜的气体渗透在图 4所示的膜模块中进行测试。图 5显示单气体渗透结果为 H2, CO2, N2, CH4, c3h6, 和 C3h8从 ZIF-8/AAO 和 ZIF-8/PAN 膜。ZIF-8/AAO 膜显示一个相当高的 h2磁导 8.3 x 10-6摩尔 m-2 s-1 Pa-1, 和理想的选择性 h2/CO2, h2/N2, h2/CH4, h2/C3小时6, h2/c 3 h6, 和 h2/c3, 8 @ 7.3, 0.3 @ 15.5, 1.4 @ 16.2, 1.4 @ 83.9, 7.4 @ 2655, 分别;远远高于相应的努森选择性。这种高分离性能是 MOF 膜中最好的一种, 它归因于超薄选择性层 (500 nm) 和膜的几乎无缺陷特征。ZIF-8/AAO 膜还显示一个高 C3小时6渗透 9.9 x 10-8摩尔 m-2 s-1 Pa-1与理想的丙烯/丙烷选择性31.6。氧化铝支撑, 500 nm 厚的 ZIF-8 薄膜显示了一个最佳的分离性能为丙烯从丙烷纯化 (与文献的综合比较在工作中是可利用的他等)。10。
ZIF-8/PAN 膜显示 h2磁导 6.1 x 10-7摩尔 m-2 s-1 Pa-1, 和理想的选择性 h2/CO2, h2/N2, h2/CH4, h2/C3h6, h2/c3h6, 和 H2/c3H8是 3.3, 13.3, 11.4, 79.0 和187。ZIF-8/PAN 膜下的气体渗透力主要是由于 PAN 支护与氧化铝支撑9相比, 其气运阻力显著提高。
总之, 我们提出了一个可重现的结晶协议 MOF 薄膜和膜。通过这一方法, 研究人员可以通过改变电场和沉积时间来精确控制异质核, 即使是从稀释后的前驱体溶液中。通过选择不同的生长条件, 可以独立控制薄膜的生长, 从而合成高性能膜。

薄分子筛膜为分子分离提供了高能效, 可降低燃料的总成本, 共2捕获、净水、溶剂回收等1、2。MOFs 是一种有希望的材料, 用于合成分子筛膜, 因为它涉及 isoreticular 合成化学和相对直接的结晶3。迄今为止, 包括 ZIF-4、-7、-8、-9、-11、-67、90、93、UiO-66、HKUST-1 和 MIL-53 在内的各种晶体结构的 MOF 膜已报告4、5。这些膜是通过结晶高品质的多晶 MOF 薄膜上的一个孔的支持合成。通常, 为了获得较高的分离选择性, 有必要减少多晶 MOF 薄膜 (如针孔和晶界缺陷) 的缺陷。一种减少缺陷的简便方法是将厚膜结晶。毫不奇怪, 早些时候报告的 MOF 膜的一些是非常厚的 (超过5µm)。不幸的是, 厚膜导致一个长扩散路径, 这限制了膜渗透。因此, 在提高选择性的同时, 也牺牲了渗透。为了规避这种权衡, 必须开发方法来结晶超薄 (< 0.5 µm 厚), 无缺陷的 MOF 薄膜。
ZIF-8 是最密集的研究 MOF 为膜合成, 由于其特殊的化学和热稳定性和简单的结晶化学6,7。到目前为止, 所报道的超薄 ZIF-8 膜是通过改变底层多孔基底的表面化学或拓扑来实现的, 有利于 ZIF-8 的异质核, 这对于共生矿多晶硅薄膜是必不可少的。例如, 陈等。报道了1µm 厚 ZIF-8 膜的合成 (3-氨基丙基) triethoxysilane 改性2涂层聚偏氟乙烯 (PVDF) 中空纤维8。他们观察了高异质核密度并且归因于它对表面化学和纳米结构的同时修改。Peinemann 集团报告了一种金属螯合, polythiosemicarbazide (PTSC) 支持9的超薄 ZIF-8 膜。这种独特的金属螯合能力 PTSC 导致了锌离子的结合, 促进了 ZIF-8 的异质核, 进而导致高性能 ZIF-8 膜。一般而言, 调整基体化学和纳米结构有利于合成高性能 MOF 膜;然而, 这些方法相当复杂, 通常无法重新应用于从其他有吸引力的 mof 结构中合成 MOF 膜。
在这里, 我们报告的合成超薄, 高共生矿 ZIF-8 薄膜使用一个简单和多才多艺的结晶方法, 可以重新应用, 形成一个薄薄的共生矿薄膜的几个水晶材料10。我们展示了 ZIF-8 和 ZIF-7 膜的例子, 没有任何基体预处理, 这大大简化了制备过程。ZIF-8 薄膜是在广泛的基体 (陶瓷, 聚合物, 金属, 碳和石墨烯) 上制备的。500纳米厚的阳极氧化铝 (氧化铝) 的 ZIF-8 膜显示出具有吸引力的分离性能。高 H2 磁导 8.3 x 10-6摩尔 m-2 s-1 Pa-1和诱人的理想选择性 7.3 (h2/CO2), 15.5 (h 2/N2), 16.2 (h2/CH4), 和 2655 (h2/C3小时8) 实现。
实现上述壮举的结晶方法已经颁布。将 ZIF-8 原子核直接从晶体的前体溶胶沉积到基体上。该方法利用环保署的时间非常短 (1-4 分钟) 后的感应时间 (原子核出现在前体溶胶)。电场在带电的 MOF 原子核中的应用驱使它们朝着一个与外加电场强度成正比的电极, 胶体 (μ) 的电泳流动性, 以及浓度原子核 (Cn), 如等式1和2所示。
<img alt="Equation 1" src="/files/ftp_upload/58301/58301eq1.jpg"> (等式 1)
<img alt="Equation 2" src="/files/ftp_upload/58301/58301eq2.jpg"> (等式 2)
这里 v = 漂移速度, ζ原子核的泽塔电位, 真空 的介电常数, r = 介电常数和 η = 前体溶胶的粘度。
因此, 通过控制E和溶液 pH 值 (确定ζ), 可以控制原子核的填料密度。随后在前体溶胶中密集堆积的原子核的生长使得研究人员能够获得高共生矿的多晶薄膜。

<table><tbody><tr><td>Zinc nitrate hexahydrate</td><td>Sigma-Aldrich</td><td>96482-500G</td><td>98% purity</td></tr><tr><td>2-Methylimidazole</td><td>Sigma-Aldrich</td><td>M50850-500G</td><td>99% purity</td></tr><tr><td>Benzimidazole</td><td>TCI</td><td>B0054-500G</td><td>98% purity</td></tr><tr><td>Tape</td><td>DuPont</td><td>KPT-1/8</td><td></td></tr><tr><td>Epoxy</td><td>GC Electronics</td><td>19-823</td><td></td></tr><tr><td>Copper foil</td><td>Alfa Aesar</td><td>13380.CV</td><td>99.9% purity</td></tr><tr><td>Power source for EPD</td><td>Gamry Instruments</td><td>Interface 1000E Potentiostat</td><td></td></tr><tr><td>Ultrasonic cleaner</td><td>MTI corporation</td><td>VGT-1860QTD</td><td></td></tr><tr><td>AAO</td><td>GE Healthcare Life Sciences&amp;lrm;</td><td>6809-7013</td><td></td></tr><tr><td>PAN</td><td>Shandong MegaVision</td><td></td><td>The molecular weight cut-off is 100 kDa</td></tr></tbody></table>

electrophoretic crystallization of ultrathin high-performance metal-organic framework membranes

我们报告的合成薄, 高共生矿, 多晶金属-有机框架 (MOF) 膜上广泛的未经修改的孔隙和非孔隙的支持 (聚合物, 陶瓷, 金属, 碳和石墨烯)。我们开发了一种新的结晶技术, 它被称为制定的方法: 电泳核组装为结晶的高共生矿薄膜 (颁布)。这种方法允许通过电泳沉积 (环保署) 直接从前体溶胶的 MOFs 在选择的基体上的异质核的高密度。包装良好的 mof 原子核的生长导致了一个高度共生矿的多晶 mof 薄膜。我们表明, 这种简单的方法可以用于合成薄, 共生矿沸石咪唑框架 (ZIF)-7 和 ZIF-8 薄膜。由此产生的 500 nm 厚的 ZIF-8 膜显示一个相当高的 H2渗透 (8.3 x 10-6摩尔 m-2 s-1 Pa-1) 和理想气体选择性 (7.3 为 h2/CO2, 15.5 为 h2/N2,16.2 为 h2/CH4, 2655 为 h2/C3H8)。c3h6/C3h8分离的一个吸引人的性能也实现了 (c3h6的磁导 9.9 x 10 摩尔 m-8 s-2 Pa-1和 C-1h6/C3H8理想选择性31.6 在25°c)。总体而言, 由于其简单性, 制定过程可以推广到合成共生矿薄膜的多种纳米孔晶体材料。

一个自制的环保署的设置被用来合成 MOF 电影 (图 1)。扫描电镜 (SEM) 图像和 X 射线衍射 (XRD) 模式收集的 ZIF-8 核膜 (图 2)。扫描电镜用于对氧化铝支架、ZIF-8/AAO 膜、PAN 支撑、ZIF-8/PAN 膜、ZIF-8/graphene 膜、ZIF-7/AAO 膜的表面和断面形貌进行图像处理 (图 3)。在温度控制的膜模块中测量了 ZIF-8 膜的气体磁导 (图 4)。ZIF-8/AAO 和 ZIF-8/PAN 膜的气体分离性能见图 5。SEM 图像用于了解细胞核膜或 MOF 薄膜的形貌。用 XRD 模型测定了细胞核膜的结晶度。利用气体渗透数据分析了 MOF 膜的传输特性。致密核膜表明, 该方法在控制基体上的异质核密度方面具有很好的效率。生长后, 扫描电镜观察到的薄膜形貌紧凑, 无针孔, 似乎高度共生矿。气体磁导数据表明, h2/C3h8选择性高于 1000, 证明 MOF 薄膜几乎无缺陷。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58301/58301fig1.jpg"> 图 1: 环保署成立.(a) 阳极氧化铝基体通过两条胶带附着在铜电极上。(b) 阴极的平行装配和阳极连接到电源上。(c) 平行电极浸入前体溶胶中.<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58301/58301fig1large.jpg" target="_blank">请单击此处查看此图的较大版本</a>。
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/58301/58301fig2.jpg"> 图 2: ZIF-8 核膜的 SEM 图像和 XRD 模式.前两个面板显示 (a) ZIF-8 核膜在氧化铝支架上的 SEM 顶部图像, (b) 相应的横断面形貌。(c) 此面板显示了核膜 (红色) 和模拟晶体 (黑色) 的 XRD 模式。这些表征表明, ZIF-8 核膜是紧凑, 超薄, 和结晶。这个数字是从他身上复制的。10以允许。版权所有威利-VCH 出版社有限公司 & 公司 KGaA。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58301/58301fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/58301/58301fig3.jpg"> 图 3: 表面/横断面形貌.这些面板显示的表面图像和横断面形貌 (a) 氧化铝的支持, (b和c) ZIF-8/AAO 膜, (d) 泛支持, (e和f) ZIF-8/PAN 膜。这些表征表明, ZIF-8 薄膜的氧化铝和 PAN 支持是高度共生矿和超薄。这个数字是从他身上复制的。10以允许。版权所有威利-VCH 出版社有限公司 & 公司 KGaA。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58301/58301fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/58301/58301fig4.jpg"> 图 4: 用于气体磁渗透测量的膜模块.ZIF-8 膜密封在本模块内。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58301/58301fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/58301/58301fig5.jpg"> 图 5: 获得的 ZIF-8/AAO 和 ZIF-8/PAN 膜的气体分离性能。 前两个面板显示气体渗透作用的动能直径为 (a) ZIF-8/AAO 和 (b) ZIF-8/PAN 膜在25°c 和 0.1 MPa。另外两个面板显示了理想的选择性作为动力学直径的功能 (c) 的 ZIF-8/AAO 和 (d) ZIF-8/PAN 膜。这些数字显示了 ZIF-8 膜的优良气体分离性能, 表明 ZIF-8 膜几乎无缺陷。这个数字是从他身上复制的。10以允许。版权所有威利-VCH 出版社有限公司 & 公司 KGaA。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58301/58301fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes at JoVE.com

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

超薄高性能金属-有机骨架膜的电泳结晶

本文提出了一种简单、重现性好、通用性强的共生矿、多晶金属有机骨架膜的合成方法。

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

electrophoretic-crystallization-ultrathin-high-performance-metal

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.9K 次观看.  École Polytechnique Fédérale de Lausanne (EPFL). 本文提出了一种简单、重现性好、通用性强的共生矿、多晶金属有机骨架膜的合成方法。

视频: Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

增强型氟烷烃的化学气相沉积等离子通过疏水金属 - 有机骨架的制备氨的去除

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

科研

化学

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

功能化的合成与表征金属 - 有机骨架

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

对磷酸增强富集制备高度多孔配位聚合物涂层的孔聚合物石柱的

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

From Constructs to Crystals &#8211; Towards Structure Determination of &#946;-barrel Outer Membrane Proteins

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% percent of known structures. There are two types of membrane proteins, &#945;-helical and &#946;-barrel. While &#945;-helical membrane proteins can be found in nearly all cellular membranes, &#946;-barrel membrane proteins can only be found in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. One common bottleneck in structural studies of membrane proteins in general is getting enough pure sample for analysis. In hopes of assisting those interested in solving the structure of their favorite &#946;-barrel outer membrane protein (OMP), general protocols are presented for the production of target &#946;-barrel OMPs at levels useful for structure determination by either X-ray crystallography and/or NMR spectroscopy. Here, we outline construct design for both native expression and for expression into inclusion bodies, purification using an affinity tag, and crystallization using detergent screening, bicelle, and lipidic cubic phase techniques. These protocols have been tested and found to work for most OMPs from Gram-negative bacteria; however, there are some targets, particularly for mitochondria and chloroplasts that may require other methods for expression and purification. As such, the methods here should be applicable for most projects that involve OMPs from Gram-negative bacteria, yet the expression levels and amount of purified sample will vary depending on the target OMP.

&#946;-barrel outer membrane proteins (OMPs) serve many functions within the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Here, we hope to alleviate a known bottleneck in structural studies by presenting protocols for the production of &#946;-barrel OMPs in sufficient quantities for structure determination by X-ray crystallography or NMR spectroscopy.

从构造到晶体 - 迈向β桶外膜蛋白的结构解析

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% ...

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

层 - 层的合成和独立式共轭微孔聚合物纳米薄膜的转移

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the lipidic cubic phase or in meso method. The method has been shown to be quite versatile in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and alpha-helical and beta-barrel proteins. Recent successes using in meso crystallization are the human engineered beta2-adrenergic and adenosine A2a G protein-coupled receptors. Protocols are presented for reconstituting the membrane protein into the monoolein-based mesophase, and for setting up crystallizations in the manual mode. Additional steps in the overall process, such as crystal harvesting, are to be addressed in future video articles. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour.

Herein is described the procedure implemented in the Caffrey Membrane Structural and Functional Biology Group to set up manually crystallization trials of membrane proteins in lipidic mesophases.

使用油脂介孔结构的测定结晶膜蛋白

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the ...

生物学

Assessing Two-dimensional Crystallization Trials of Small Membrane Proteins for Structural Biology Studies by Electron Crystallography

Electron crystallography has evolved as a method that can be used either alternatively or in combination with three-dimensional crystallization and X-ray crystallography to study structure-function questions of membrane proteins, as well as soluble proteins. Screening for two-dimensional (2D) crystals by transmission electron microscopy (EM) is the critical step in finding, optimizing, and selecting samples for high-resolution data collection by cryo-EM. Here we describe the fundamental steps in identifying both large and ordered, as well as small 2D arrays, that can potentially supply critical information for optimization of crystallization conditions.
By working with different magnifications at the EM, data on a range of critical parameters is obtained. Lower magnification supplies valuable data on the morphology and membrane size. At higher magnifications, possible order and 2D crystal dimensions are determined. In this context, it is described how CCD cameras and online-Fourier Transforms are used at higher magnifications to assess proteoliposomes for order and size.
While 2D crystals of membrane proteins are most commonly grown by reconstitution by dialysis, the screening technique is equally applicable for crystals produced with the help of monolayers, native 2D crystals, and ordered arrays of soluble proteins. In addition, the methods described here are applicable to the screening for 2D crystals of even smaller as well as larger membrane proteins, where smaller proteins require the same amount of care in identification as our examples and the lattice of larger proteins might be more easily identifiable at earlier stages of the screening.

Evaluating two-dimensional (2D) crystallization trials for the formation of ordered membrane protein arrays is a highly critical and difficult task in electron crystallography. Here we describe our approach in screening for and identifying 2D crystals of predominantly small membrane proteins in the range of 15 &#x2013; 90kDa.

评估电子晶体结构生物学研究的小膜蛋白的二维结晶试验

Electron crystallography has evolved as a method that can be used either alternatively or in combination with three-dimensional crystallization and X-ray ...

聚合物接枝金属有机框架单层的自组装

Synthesis and Characterization of Self-Assembled Metal-Organic Framework Monolayers Using Polymer-Coated Particles

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. Attempts to enhance the utility of MOFs have involved the preparation of various composites, including polymer-grafted MOFs. By directly grafting polymers to the external surface of MOFs, issues of incompatibility between polymers and MOFs can be overcome. Polymer brushes grafted from the surface of MOFs can serve to stabilize the MOF while enabling particle assembly into self-assembled metal-organic framework monolayers (SAMMs) via polymer-polymer interactions.
Control over the chemical composition and molecular weight of the grafted polymer can allow for tuning of the SAMM characteristics. In this work, instructions are provided on how to immobilize a chain transfer agent (CTA) onto the surface of the MOF UiO-66 (UiO = Universitetet i Oslo). The CTA&#160;serves as initiation sites for the growth of polymers. Once polymer chains are grown from the MOF surface, the formation of SAMMs is achieved through self-assembly at an air-water interface. The resulting SAMMs are characterized and shown to be freestanding by scanning electron microscopy imaging. The methods presented in this paper are expected to make the preparation of SAMMs more accessible to the research community and thereby expand their potential use as a&#160;MOF-polymer composite.

作者聚焦:探索自组装的 MOF-聚合物复合材料

A protocol for the synthesis and characterization of self-assembled metal-organic framework monolayers is provided using polymer-grafted, metal-organic framework (MOF) crystals. The procedure shows that polymer-grafted MOF particles can be self-assembled at an air-water interface resulting in well-formed, free-standing, monolayer structures as evidenced by scanning electron microscopy imaging.

使用聚合物包覆颗粒的自组装金属有机框架单层的合成和表征

Metal-organic frameworks (MOFs) are materials with potential applications in fields such as gas adsorption and separation, catalysis, and biomedicine. ...

超薄高性能金属-有机骨架膜的电泳结晶

摘要

探索更多视频

此视频中的章节

增强型氟烷烃的化学气相沉积等离子通过疏水金属 - 有机骨架的制备氨的去除

功能化的合成与表征金属 - 有机骨架

对磷酸增强富集制备高度多孔配位聚合物涂层的孔聚合物石柱的

从构造到晶体 - 迈向β桶外膜蛋白的结构解析

层 - 层的合成和独立式共轭微孔聚合物纳米薄膜的转移

使用油脂介孔结构的测定结晶膜蛋白

评估电子晶体结构生物学研究的小膜蛋白的二维结晶试验

使用聚合物包覆颗粒的自组装金属有机框架单层的合成和表征

使用聚合物包覆颗粒的自组装金属有机框架单层的合成和表征

使用聚合物包覆颗粒的自组装金属有机框架单层的合成和表征