INQUIMAE, CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA, Argentina.
J Am Chem Soc. 2010 Sep 8;132(35):12404-11. doi: 10.1021/ja104152g.
Solid state nanochannels modified with supramolecular architectures are a new and interesting class of stimuli-responsive nanofluidic element. Their fundamental understanding requires describing the behavior of soft-materials in confined geometries and its responses to changes in solution conditions. Here, a nanochannel modified with a polyelectrolyte brush is studied with a molecular theory that incorporates the conformational behavior of the polymers, electrostatic, van der Waals, and repulsive interactions coupled with the ability of the polymer segments to regulate their charge through acid-base equilibrium. The theory predicts pH-dependent ionic conductivity in excellent agreement with experimental observations. The polymer chains undergo large conformational changes triggered by variations in the outer solution environment and the conductivity of the device is shown to be controlled by the charge state of the polymer. The degree of polymer charge is largely affected by charge regulation and nanoconfinement effects. The molecular calculations show that the apparent pK(a) inside the pore departs from that in solution when increasing the curvature of the nanochannel.
用超分子结构修饰的固态纳米通道是一类新的、有趣的刺激响应纳米流元件。要深入理解这类元件，就需要描述处于受限几何形状下的软物质的行为及其对溶液条件变化的响应。在本文中，我们利用一种分子理论研究了经聚电解质刷修饰后的纳米通道，该理论将聚合物的构象行为、静电、范德华和排斥相互作用与聚合物链段通过酸碱平衡来调节其电荷的能力结合起来。该理论预测出的 pH 值依赖性离子电导率与实验观察结果非常吻合。聚合物链在外溶液环境变化的触发下发生了大的构象变化，并且器件的电导率被证明可通过聚合物的电荷状态来控制。聚合物的电荷程度在很大程度上受到电荷调节和纳米约束效应的影响。分子计算表明，当纳米通道的曲率增加时，腔内的表观 pK(a) 会偏离溶液中的 pK(a)。
