Synthesis and characterisation of chitosan - nitrogen polyphosphonic acid poly(organosiloxane) high temperature proton exchange membranes for fuel cells

摘要

One kind of acid-base high temperature proton exchange membrane was synthesised from chitosan (CS), 3-aminopropyltriethoxysilane (APTES) and amino trimethylene phosphonic acid (ATMP) by sol-gel process. In order to prevent phosphonic acid from leaching out, ATMP was introduced as proton conductor as well as cross-linker. Fourier transform infrared suggests that the Si-OC2H5 in APTES appears as a hydrolysis-polycondensation yielding Si-O-Si network, and the introduction of ATMP leads to the protonation of the amino group. These membranes are thermally stable up to similar to 180 degrees C and show excellent oxidative stability. In addition, the proton conductivity of CS/APTES/ATMP membranes increases with increasing temperature, reaching the value of 0.0578 S cm(-1) at 140 degrees C under normally anhydrous condition, which indicates that the acid-base pair and hydrogen bond network in CS/APTES/ATMP membranes are favourable to proton transfer.