Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019 Auckland, New Zealand.
J Phys Chem B. 2011 Feb 24;115(7):1652-61. doi: 10.1021/jp109455m. Epub 2011 Feb 2.
This study elucidates the charge transport processes of polyaniline (PANI) composite membranes and correlates them to the PANI deposition site and the extent of PANI surface layering on the base microporous membranes. PANI was deposited either as a surface layer or inside the pores of cellulose acetate microporous membranes using various in situ chemical polymerization techniques. The extent of PANI layering at the surface of the base membrane and its oxidation and doping states were characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). PANI deposition on the membranes showed a strong dependence on the polymerization technique and polymerization time within a single technique. In XPS, the deconvolution of C 1s and N 1s core-level spectra of the composite membranes was used to quantify the extent of PANI layering at the surface along with its oxidation and doping states. PANI incompletely covered the surface of the base microporous membranes for all the employed techniques. However, the extent of the layering increased with the polymerization time in a particular technique. The charge transport through the bulk membrane and charge transfer at the membrane/electrode interface were studied by electrochemical impedance spectroscopy (EIS). The data were analyzed using the equivalent circuit modeling technique. The modeling parameters revealed that PANI deposition at the surface enhanced the interfacial charge transfer but the process depended on the extent of the surface coverage of the membrane. In addition, the charge transport in the bulk membrane depended on the PANI intercalation level, which varied depending on the polymerization technique employed. In addition, the EIS of electrolyte-soaked membranes was also conducted to evaluate the effects of PANI deposition site on charge transport in the presence of an electrolyte. PANI layering at the pore walls of the base membrane from diaphragmatic polymerization in a two-compartment cell showed that charge transport processes were strongly affected by the interaction of the electrolyte with the PANI layer at the pore surface. This study successfully showed the dependence of charge transport mechanisms of PANI composite membranes on the PANI deposition site and extent of surface layering at the membrane surface.
这项研究阐明了聚苯胺（PANI）复合膜的电荷传输过程，并将其与 PANI 的沉积位置以及 PANI 在基底微孔膜表面的分层程度相关联。通过各种原位化学聚合技术，将 PANI 沉积在醋酸纤维素微孔膜的表面层或孔内。使用傅里叶变换红外（FTIR）光谱和 X 射线光电子能谱（XPS）对基底膜表面的 PANI 分层程度及其氧化和掺杂状态进行了表征。PANI 在膜上的沉积强烈依赖于聚合技术和聚合时间，即使在单一技术中也是如此。在 XPS 中，复合膜的 C 1s 和 N 1s 芯层谱的分峰处理用于定量表面上 PANI 的分层程度及其氧化和掺杂状态。对于所有使用的技术，PANI 都不完全覆盖基底微孔膜的表面。然而，在特定技术中，随着聚合时间的增加，分层程度增加。通过电化学阻抗谱（EIS）研究了通过块状膜的电荷传输和膜/电极界面处的电荷转移。使用等效电路建模技术对数据进行了分析。模型参数表明，表面上的 PANI 沉积增强了界面电荷转移，但该过程取决于膜的表面覆盖率。此外，块状膜中的电荷传输取决于 PANI 的插层水平，这取决于所使用的聚合技术。此外，还进行了电解质浸泡膜的 EIS 测试，以评估 PANI 沉积位置对电解质存在下电荷传输的影响。在两室电池中通过隔膜聚合在基底膜的孔壁上进行的 PANI 分层表明，电荷传输过程受到电解质与孔表面处 PANI 层相互作用的强烈影响。这项研究成功地表明了 PANI 复合膜的电荷传输机制取决于 PANI 的沉积位置和膜表面的分层程度。
