Barjola Arturo, Escorihuela Jorge, García-Bernabé Abel, Sahuquillo Óscar, Giménez Enrique, Compañ Vicente
Instituto de Tecnología de Materiales, Universitat Politècnica de València Camino de Vera s/n 46022 Valencia Spain.
Departamento de Química Orgánica, Universitat de València Av. Vicente Andrés Estellés s/n, Burjassot 46100 Valencia Spain
RSC Adv. 2021 Aug 2;11(42):26379-26390. doi: 10.1039/d1ra05364g. eCollection 2021 Jul 27.
In this article, PBI composite membranes containing the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM-NTf) at 1, 5, 10, 20 and 50 wt% (named PBI-IL-) have been prepared by a casting method. The internal morphology of the membranes was analyzed by scanning electron microscopy (SEM), revealing that the incorporation of IL promotes the formation of porous channels. Thermal and mechanical stability was confirmed by thermogravimetric analysis (TGA) and tensile test measurements. The ionic transport through membranes was analysed by means of electrochemical impedance spectroscopy (EIS), showing a dependence on the IL loading, reaching a highest conductivity value of 1.8 × 10 S cm for the PBI-IL-50 membrane at 160 °C. The experimental results showed a Vogel-Fulcher-Tammann (VFT) type relation for the ionic conductivity with temperature and the calculated activation energies suggest that ionic conduction in the films can occur by both hopping and vehicle-type mechanisms. Eyring's absolute rate theory was also used to obtain activation enthalpy and entropy from the temperature dependence of the conductivity. Diffusivity and free ion number density were obtained by means of electrode polarization analysis to obtain more insight into the conduction in these composite membranes. Finally, the Debye length was calculated and related to both transport parameters.
在本文中，通过流延法制备了含有1、5、10、20和50 wt%离子液体（IL）1-丁基-3-甲基咪唑双（三氟甲基磺酰）亚胺（BMIM-NTf）的PBI复合膜（命名为PBI-IL-）。通过扫描电子显微镜（SEM）分析了膜的内部形态，结果表明IL的加入促进了多孔通道的形成。通过热重分析（TGA）和拉伸试验测量证实了热稳定性和机械稳定性。通过电化学阻抗谱（EIS）分析了离子在膜中的传输，结果表明其依赖于IL负载量，在160°C时，PBI-IL-50膜的电导率最高达到1.8×10 S cm。实验结果表明离子电导率与温度呈Vogel-Fulcher-Tammann（VFT）型关系，计算得到的活化能表明薄膜中的离子传导可通过跳跃和载流子型机制发生。还利用Eyring绝对速率理论从电导率的温度依赖性中获得活化焓和熵。通过电极极化分析获得扩散系数和自由离子数密度，以更深入地了解这些复合膜中的传导。最后，计算了德拜长度并将其与两个传输参数相关联。
