Potential-induced wetting and dewetting in pH-responsive block copolymer membranes for mass transport control
Potential-induced wetting and dewetting in pH-responsive block copolymer membranes for mass transport control
复制标题
用于质量传输控制的 pH 响应性嵌段共聚物膜中的电位诱导润湿和反润湿
DOI：
10.1039/d1fd00048a
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发表时间：
2022
影响因子：
3.4
通讯作者：
Bohn, Paul W.
中科院分区：
文献类型：
--
作者：
Kwon, Seung-Ryong;Baek, Seol;Bohn, Paul W.
通道限制疏水体积中的润湿和脱湿行为用于生物膜中影响选择性离子/分子运输。人工仿生疏水纳米孔是利用润湿和脱湿来设计的，然而，为了实现可控释放/传输、水分离/净化和能量转换等应用，需要利用多种传输模式进行可调的质量传输控制。在这里，我们研究了由聚苯乙烯-b-聚（4-乙烯基吡啶）（PS-b-P4VP）嵌段共聚物（BCP）组成的ph响应膜在纳米孔电极阵列（NEA）（即BCP@NEA）上作为分层组织的三明治结构时的电位诱导润湿和脱湿行为。在pH < pKa(P4VP) （pKa ~ 4.8）时，由于P4VP圆柱形纳米结构域亲水、质子化，BCP充当阴离子交换膜，但在pH为> pKa（P4VP）时，P4VP结构域表现出电荷中性、疏水和坍塌的结构，阻碍了通过疏水膜的质量运输。然而，当最初在脱水条件下制备时，如果对BCP@NEA结构施加足够的负电位，BCP膜中的质量传输可能会开启。当疏水BCP膜被引入到2电极嵌入的纳米孔阵列上时，电解质溶液被引入到纳米孔中，然后通过利用BCP膜中电位诱导的润湿和脱湿转变被隔离。在BCP@NEA结构中，电位诱导的润湿/脱湿转变和对循环伏安法的影响表征为电位、pH和离子强度的函数。此外，时间电流法和氧化还原循环实验用于进一步表征电位响应。在这项工作中提出的多模态质量传递系统将有助于超灵敏传感和单分子研究，这些研究需要长时间的监测来探索反应动力学以及纳米限制体积内的分子异质性。
Wetting and dewetting behavior in channel-confined hydrophobic volumes is used in biological membranes to effect selective ion/molecular transport. Artificial biomimetic hydrophobic nanopores have been devised utilizing wetting and dewetting, however, tunable mass transport control utilizing multiple transport modes is required for applications such as controllable release/transport, water separation/purification and energy conversion. Here, we investigate the potential-induced wetting and dewetting behavior in a pH-responsive membrane composed of a polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) when fabricated as a hierarchically-organized sandwich structure on a nanopore electrode array (NEA), i.e. BCP@NEA. At pH < pKa(P4VP) (pKa ∼ 4.8), the BCP acts as an anion-exchange membrane due to the hydrophilic, protonated P4VP cylindrical nanodomains, but at pH > pKa(P4VP), the P4VP domains exhibit charge-neutral, hydrophobic and collapsed structures, blocking mass transport via the hydrophobic membrane. However, when originally prepared in a dewetted condition, mass transport in the BCP membrane may be switched on if sufficiently negative potentials are applied to the BCP@NEA architecture. When the hydrophobic BCP membrane is introduced on top of 2-electrode-embedded nanopore arrays, electrolyte solution in the nanopores is introduced, then isolated, by exploiting the potential-induced wetting and dewetting transitions in the BCP membrane. The potential-induced wetting/dewetting transition and the effect on cyclic voltammetry in the BCP@NEA structures is characterized as a function of the potential, pH and ionic strength. In addition, chronoamperometry and redox cycling experiments are used to further characterize the potential response. The multi-modal mass transport system proposed in this work will be useful for ultrasensitive sensing and single-molecule studies, which require long-time monitoring to explore reaction dynamics as well as molecular heterogeneity in nanoconfined volumes.