화학공학소재연구정보센터
International Journal of Hydrogen Energy, Vol.40, No.48, 17316-17322, 2015
Theoretical methodology for calculating water uptake and ionic exchange capacity parameters of ionic exchange membranes with applications in fuel cells
The water uptake (WU) and ionic exchange capacity (IEC) are important parameters for proton exchange membranes (PEMs), WU represents their total water content, while IEC is the measure of the ability of the membrane to facilitate movement of H3O+ ions, located in the aqueous environment, through the -SO3- sulfonyl groups anchored in their structure. IEC is also the measure of relative concentration of acid groups within polymer electrolyte membrane. According to the vehicle mechanism of proton transport,. an appropriate amount of water content and a suitable value of IEC in PEMs are necessary for achieving high proton conductivity. In this work, studies based on density functional theory (DFT), molecular mechanics (MM) and dynamics molecular (DS) were realized in order to develop a theoretical methodology to obtain these parameters. Our proposal considers the ionomer, the solvation medium and the interactions between the ionomer and water molecules. The methodology is applied to structures of sulfonated poly(ether-imide) (SPEI) with (-SO3H)(n) (n = 1,... 6) groups. These structures were built and optimized aiming to obtain above properties as a function of the number of sulfonyl groups. The comparative study demonstrates the SPEI with four sulfonyl groups is the polymer having better properties for successful operation in Fuel Cell. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.