Electrically Mediated Membrane Pore Gating via Grafted Polymer Brushes,ACS Materials Letters

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Electrically Mediated Membrane Pore Gating via Grafted Polymer Brushes
ACS Materials Letters ( IF 9.6 ) Pub Date : 2019-11-11 , DOI: 10.1021/acsmaterialslett.9b00298
Chia Miang Khor ₁ , Xiaobo Zhu ₁ , Marco S. Messina _{2,

3} , Sidney Poon ₁ , Xuan Yu Lew ₁ , Heather D. Maynard _{2,

3} , David Jassby _{1,

3}

Affiliation

Stimuli-responsive membranes that enable the smart control of membrane transport properties represent an interesting class of materials for a wide range of separation processes. In this work, surface-initiated, electrochemically mediated atom transfer radical polymerization was used to grow poly(acrylic acid) brushes from the surface of a percolating network of carbon nanotubes coating an ultrafiltration membrane. Brush molecular weights as high as 930 kDa were achieved, with very low dispersivity. When no potential was applied, the material was able to reject 88% of 12 kDa dextran in 50 mM NaCl solution. Membrane rejection and flux were readily changed upon the application of electrical potentials, with positive potentials increasing flux by 85% and reducing rejection by 56%, while negative potentials reduced flux by 30% and increased rejection by 5%. We show evidence that counterion migration, moving in response to the applied electric field, is responsible for the expansion or collapse of the grafted charged polymer brushes, which induced or eliminated pore gating. In addition, atomic force microscopy was used to probe the forces exerted by brush conformational changes in response to the applied field. These materials can find applications in industrial separations where gating is needed and may possess interesting anti-fouling properties.

中文翻译：

通过接枝聚合物刷进行电介导的膜孔选通

能够对膜传输特性进行智能控制的刺激响应膜代表了用于广泛分离过程的一类有趣的材料。在这项工作中，表面引发的电化学介导的原子转移自由基聚合被用来从覆盖超滤膜的碳纳米管渗滤网络的表面生长聚（丙烯酸）刷。刷子的分子量高达930 kDa，分散度非常低。当未施加电势时，该材料能够排斥50 mM NaCl溶液中88％的12 kDa右旋糖酐。施加电势后，膜截留率和通量很容易改变，正电位使通量增加85％，使截留率降低56％，而负电位可将磁通量减少30％，将排斥率增加5％。我们显示的证据表明，抗衡离子迁移（响应于所施加的电场而移动）是导致接枝的带电聚合物刷膨胀或塌陷的原因，而后者导致或消除了孔门控。另外，原子力显微镜被用来探测由刷子的构象变化响应于所施加的场而施加的力。这些材料可用于需要选通的工业分离中，并且可能具有令人感兴趣的防污性能。原子力显微镜用于探测刷子的构型变化对所施加的场的响应所施加的力。这些材料可用于需要选通的工业分离中，并且可能具有令人感兴趣的防污性能。原子力显微镜用于探测刷子的构型变化对所施加的场的响应所施加的力。这些材料可用于需要选通的工业分离中，并且可能具有令人感兴趣的防污性能。

更新日期：2019-11-13

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