International Journal of Energy Research, Vol.44, No.3, 1607-1623, 2020
Application of a novel PUB enhanced semi-interpenetrating chitosan-based anion exchange membrane
A novel OH- conducting membrane containing chitosan (CS), poly-(acrylamide-co-diallyldimethylammonium chloride) (PAADDA) and linear structured poly-bis (2-chloroethyl) ether-1,3-bis [3-(dimethylamino)propyl] urea copolymer (PUB) was synthesized via a solution-casting method and subsequently modified by hot treatment and chemical cross-linking. The structural characterizations of scanning electron microscope (SEM), atomic force microscope (AFM), Fourier transform infrared spectra (FT-IR), and X-ray photoelectron spectroscopy (XPS) were carried out, showing that CS, PAADDA, and PUB formed a compact interpenetrating polymer network structure without apparent phase separation phenomenon under the help of cross-linking. By changing the content of PUB in the membrane, the application performance such as mechanical properties, thermal gravimetric (TG) analysis, water uptake (WU), OH- conductivity (sigma OH-) and ion exchange capacity (IEC) were investigated to evaluate the feasibility for alkaline membrane fuel cells. The maximum OH- conductivity could be reached up to 3.12 x 10(-2) S cm(-1) at 80 degrees C in a mass ratio of CS/PAADDA/PUB (1:0.5:0.5) while a good tensile strength of 22.73 MPa and an excellent elongation at break of 23.55% could be obtained in a mass ratio of CS/PAADDA/PUB (1:0.5:0.25). Furthermore, the membrane also exhibited relatively high oxidative stability as well as excellent alkaline resistance stability, when conditioned in 30% H2O2 solution at ambient temperature for 120 hours and 8 M KOH solution at 60 degrees C for 320 hours, respectively. Membrane electrode assemblies (MEAs) achieved a peak power density of 38.1 mW cm(-2) at the maximum current density of 73.2 mA cm(-2) in a H-2/O-2 system at room temperature. PUB was successfully introduced into the CS-based membrane to improve the conductivity. Maximum OH- conductivity reached 0.016 S cm(-1) at room temperature. Tensile strength of the prepared membrane could reach up to 22.73 MPa. The prepared membrane exhibited an excellent elongation at break of 23.55%. The membrane showed good oxidative stability and excellent alkaline resistance stability.