Synthesis and Conductive Property of Alkaline Anion-Exchange Membranes Based on Poly(vinyl alcohol)/Bis(2-chloroethyl) Ether-1,3-bis[3-(dimethylamino)propyl] Urea Copolymer Composite

Anion-exchange membrane fuel cells (AEMFCs) researches have recently made a noticeable comeback from proton-exchange membrane fuel cells (PEMFCs) dominant era, since the AEMFCs can get faster electrokinetics, lower fuel crossover, reduced CO poisoning, and use of non-precious metal catalysts^1,2. In the development of AEMFCs, the conductivity of  alkaline anion-exchange membranes (AEMs) is considered to be the most chanellagen, since the mobility of OH^- is only 1/4 of that of the H⁺ transportation (membranes that conduct H⁺ cations), the membranes that can have high OH^- conductivity are highly desired for making a breakthrough in AEMFCs performances³. In cases where much effort has been undertaken for the above purpose and some promising candidates have been proposed such as quaternized polysulphane (PS)⁴, poly(ether imide) (PEI)⁵ and radiationgrafted PVDF and FEP⁶. However, these polymers were generally of high price and their quaternization is complex process. 

Chitosan (CS) is a low-cost biopolymer, which has very good mechanical and chemical stability along with good film formation property⁷. However, since CS is just a weak alkaline conductivity, it cannot be directly used to fuel cell membrane. In this work, we report a novel series of alkaline anion-exchange membranes: Chitosan /Bis(2-chloroethyl)ether-1,3-bis[3-(dimethylamino)propyl]urea copolymer (PUB) membranes. By incorporation of PUB, the OH^- conductivity of the CS/PUB membrane was found to be greatly improved and reached high up to 8.610×10^-3S cm^-1 at 70^oC.