Synthesis and characterization of sulfonated poly(aromatic imide-co-aliphatic imide) (S-coPI) membrane for direct methanol fuel cells

Abstract

A novel polymer electrolyte membrane (PEM) based on sulfonated poly(aromatic imide-co-aliphatic imide) (S-coPI) is synthesized by the polycondensation of 3,3 0 ,4,4 0 -benzophenonetetracarboxylic dianhydride (BPTDA) with 4,4 0 -diaminodiphenylmethane (DDM), 4,4 0 -diaminodiphenylmethane-3,3 0 -disulfonic acid disodium salt (S-DDM), and adipic acid dihydrazide (ADH). The ADH is utilized to increase the flexibility of the backbone structure due to its aliphatic structure. The sulfonation degree of S-coPI is controlled by varying the mole ratio of DDM, S-DDM, and ADH. The S-DDM containing two sulfonated groups is confirmed by 1 H-NMR. S-coPI membranes are characterized by FT-IR to identify the characteristic peaks of the sulfonated group at 1,298, 1,159, 1,098, and 1,065 cm -1 . Thermogravimetric analysis is used to investigate the thermal stability of S-coPI; it undergoes 2 steps in the degradation process, one at 320°C which represents the decomposition of the sulfonated group and one at 560°C which represents the polymer backbone degradation. The S-coPI-3, with the highest sulfonation degree, possesses proton conductivity value of about 1.16 9 10 -2 S cm -1 . The methanol permeability of the S-coPI films are in the range of 3.864 9 10 -8 -6.521 9 10 -8 cm 2 s -1 , about 26-40 times lower than that of Nafion 117.

Graphene nanosheets dispersed hydrophobic and flexible aliphatic chain containing multifunctional poly(benzoxazines) nanocomposites for medium temperature proton exchange membrane fuel cell applications

“…Fuel cells are electrochemical devices that convert chemical energy directly into electricity, which has been deliberated not only as a hopeful alternative but also for its environmental friendliness for energy sources in the coming years that can replace currently used traditional fossil fuels. [1][2][3][4] Proton-exchange membrane fuel cell (PEMFC) is the best applicable device, among the various types of fuel cells, 5 for automobile applications owing to its prompt start-up, high power density, low operating temperature, and nimble reaction to operation loads, and along with the ability to prolong the parity of CO 2 , it provides smoke-free and eco-friendly transportation and could reduce global warming in the future [6][7][8][9] while replacing gasoline and diesel internal combustion transportations.…”