Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, Beijing Normal University , Beijing 100875, P. R. China.
J Am Chem Soc. 2015 Nov 25;137(46):14765-72. doi: 10.1021/jacs.5b09918. Epub 2015 Nov 16.
Engineered asymmetric membranes for intelligent molecular and ionic transport control at the nanoscale have gained significant attention and offer prospects for broad application in nanofluidics, energy conversion, and biosensors. Therefore, it is desirable to construct a high-performance heterogeneous membrane capable of coordinating highly selective and rectified ionic transport with a simple, versatile, engineered method to mimic the delicate functionality of biological channels. Here, we demonstrate an engineered asymmetric heterogeneous membrane by combining a porous block copolymer (BCP) membrane, polystyrene-b-poly(4-vinylpyridine) (PS48400-b-P4VP21300), with a track-etched asymmetric porous polyethylene terephthalate membrane. The introduction of chemical, geometrical, and electrostatic heterostructures provides our heterogeneous membrane with excellent anion selectivity and ultrahigh ionic rectification with a ratio of ca. 1075, which is considerably higher than that of existing ionic rectifying systems. This anion-selective heterogeneous membrane was further developed into an energy conversion device to harvest the energy stored in an electrochemical concentration gradient. The concentration polarization phenomenon that commonly exists in traditional reverse electrodialysis can be eliminated with an asymmetric bipolar structure, which considerably increases the output power density. This work presents an important paradigm for the use of versatile BCPs in nanofluidic systems and opens new and promising routes to various breakthroughs in the fields of chemistry, materials science, bioscience, and nanotechnology.
工程化的不对称纳米尺度分子和离子传输控制膜在纳米流体学、能量转换和生物传感器等领域具有广阔的应用前景，因此，构建一种能够协调高度选择性和整流离子传输的高性能异质膜，采用简单、多功能的工程化方法来模拟生物通道的精细功能，是非常理想的。在这里，我们通过将多孔嵌段共聚物（BCP）膜聚苯乙烯-b-聚（4-乙烯基吡啶）（PS48400-b-P4VP21300）与刻蚀不对称多孔聚对苯二甲酸乙二醇酯膜相结合，展示了一种工程化的不对称异质膜。化学、几何和静电异质结构的引入使我们的异质膜具有优异的阴离子选择性和超高的离子整流比，约为 1075，远高于现有离子整流系统。这种阴离子选择性异质膜进一步开发为能量转换装置，用于收集电化学浓度梯度中储存的能量。不对称双极结构可以消除传统反向电渗析中常见的浓度极化现象，从而大大提高输出功率密度。这项工作为在纳米流体系统中使用多功能嵌段共聚物提供了一个重要的范例，并为化学、材料科学、生物科学和纳米技术等领域的各种突破开辟了新的、有前途的途径。
