Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan, Kansas 66506-0401, USA.
Langmuir. 2011 Sep 6;27(17):11111-7. doi: 10.1021/la202005n. Epub 2011 Aug 5.
In this paper we report electrochemical investigations of the influence of organic solvents dissolved in aqueous solution on the permeability of nanoporous films derived from a cylinder-forming polystyrene-poly(methyl methacrylate) diblock copolymer (CF-PS-b-PMMA). The nanoporous films (ca. 30 nm in pore diameter) were prepared on planar gold electrodes via UV-based degradation of the cylindrical PMMA domains of annealed CF-PS-b-PMMA films (30-45 nm thick). The permeability of the electrode-supported nanoporous films was assessed using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The faradic current of Fe(CN)(6)(3-/4-) decreased upon immersion in aqueous solutions saturated with toluene or methylene chloride (5.8 mM and 0.20 M, respectively). EIS data indicated that the decrease in faradic current mainly reflected an increase in the pore resistance (R(pore)). In contrast, R(pore) did not change in a saturated n-heptane solution, 0.17 M ethanol, or 5.8 mM aqueous solutions of methylene chloride, diethyl ether, methyl ethyl ketone, or ethanol. Atomic force microscopy images of a nanoporous film in aqueous solution with and without 5.8 mM toluene showed a reversible change in the surface morphology, which was consistent with a toluene-induced change in R(pore). The solvent-induced increase in R(pore) was attributed to the swelling of the nanoporous films by the organic solvents, which decreased the effective pore diameter. The reversible permeability changes suggest that the surface of CF-PS-b-PMMA-derived nanoporous films can be functionalized in organic environments without destroying the nanoporous structure. In addition, the solvent-induced swelling may provide a simple means for controlling the permeability of such nanoporous films.
本文报道了电化学研究有机溶剂在水溶液中对由圆柱状聚苯乙烯-聚甲基丙烯酸甲酯嵌段共聚物（CF-PS-b-PMMA）衍生的纳米多孔膜渗透性的影响。纳米多孔膜（孔径约 30nm）通过在退火 CF-PS-b-PMMA 薄膜（30-45nm 厚）的圆柱形 PMMA 域上进行基于 UV 的降解，在平面金电极上制备。通过循环伏安法和电化学阻抗谱（EIS）评估电极支撑的纳米多孔膜的渗透性。浸入甲苯或二氯甲烷（分别为 5.8mM 和 0.20M）饱和水溶液中时，Fe(CN)(6)(3-/4-)的可逆电流减小。EIS 数据表明，可逆电流的减小主要反映了孔电阻（R(pore))的增加。相比之下，在饱和正庚烷溶液、0.17M 乙醇或 5.8mM 二氯甲烷、乙醚、甲基乙基酮或乙醇的水溶液中，R(pore)没有变化。在含有和不含有 5.8mM 甲苯的水溶液中的纳米多孔膜的原子力显微镜图像显示出表面形态的可逆变化，这与 R(pore) 诱导的甲苯变化一致。溶剂诱导的 R(pore)增加归因于有机溶剂使纳米多孔膜溶胀，从而减小了有效孔径。可逆的渗透性变化表明，CF-PS-b-PMMA 衍生的纳米多孔膜的表面可以在有机环境中进行功能化，而不会破坏纳米多孔结构。此外，溶剂诱导的溶胀可能为控制这种纳米多孔膜的渗透性提供一种简单的方法。
