Qaiser Asif A
Department of Chemical and Materials Engineering, The University of Auckland , Private Bag 92019, Auckland, New Zealand.
J Phys Chem B. 2014 Aug 14;118(32):9686-94. doi: 10.1021/jp409692s. Epub 2014 Aug 1.
The charge transport processes in polyaniline (PANI) composite porous membranes have been elaborated in this study using dual-transmission line impedance model conventionally used for macroscopically homogeneous (nanoporous) membranes. Mixed cellulose ester (ME)-PANI porous membranes were prepared using various in situ chemical polymerization techniques including solution- and vapor-phase polymerizations, and two-compartment cell diaphragmatic polymerization. Each technique yielded different PANI deposition site and content in the membranes. As a result, the modeling of electrochemical impedance spectroscopy (EIS) data yielded different model parameters that have been correlated with the PANI content and deposition site (i.e., surface layering versus in-bulk deposition) in the membranes. The modeling results showed that PANI deposition enhanced charge transport by shifting the interfacial transfer mechanism at pore walls from simple double layer charging to the charge transfer involving oxidation of PANI molecular chains deposited at the pore walls of the composite membranes. In addition, in-bulk PANI deposition in the membranes by means of two-compartment cell polymerization showed several orders of magnitude faster charge transport as compared to the membranes where PANI deposited only at the surface. This study shows that pore-controlled diffusion in PANI composite porous membranes can be satisfactorily modeled using dual-transmission line model and correlated with PANI deposition site in the membranes.
本研究采用传统上用于宏观均匀（纳米多孔）膜的双传输线阻抗模型，阐述了聚苯胺（PANI）复合多孔膜中的电荷传输过程。使用各种原位化学聚合技术制备了混合纤维素酯（ME）-PANI多孔膜，包括溶液聚合和气相聚合以及两室电池隔膜聚合。每种技术在膜中产生不同的PANI沉积位点和含量。结果，电化学阻抗谱（EIS）数据的建模产生了不同的模型参数，这些参数与膜中PANI的含量和沉积位点（即表面分层与体相沉积）相关。建模结果表明，PANI沉积通过将孔壁处的界面转移机制从简单的双层充电转变为涉及复合膜孔壁处沉积的PANI分子链氧化的电荷转移，从而增强了电荷传输。此外，与仅在表面沉积PANI的膜相比，通过两室电池聚合在膜中进行体相PANI沉积显示出几个数量级更快的电荷传输。本研究表明，使用双传输线模型可以令人满意地模拟PANI复合多孔膜中的孔控扩散，并与膜中PANI的沉积位点相关联。
