Synthesis and characterization of sulfonated polytriazoles utilizing 1,4-bis(4-azido-2-(trifluoromethyl)phenoxy)benzene for the proton exchange membrane applications

The aromatic hydrocarbon-based sulfonated polytriazoles have a reputation as a high-performing polymer because of their excellent properties. This work demonstrates the synthesis of a new semi-fluorinated diazide monomer, that is, 1,4-bis(4-azido-2-(trifluoromethyl)phenoxy)benzene (BATFB), and exploiting this compound a series of aromatic hydrocarbon-based semi-fluorinated sulfonated polytriazoles (BABPSSH-60, -70, -80, -90) was synthesized utilizing the Cu(I)-induced "click" cycloaddition polymerization reaction along with the sulfonated diazide monomer, 4,4 '-diazido-2,2 '-stilbenesulfonic acid disodium salt tetrahydrate (DASSA) and the terminal dialkyne monomer, 4,4 '-(propane-2,2 '-diyl)bis((prop-2-ynyloxy)benzene) (BPAAL). The structural analysis of those copolymers was completed by the FTIR and the NMR (H-1 and C-13) spectroscopic methods. Further, the degree of sulfonation (DS) and the ion exchange capacity (IEC) values of the copolymers were confirmed using the H-1 NMR spectrums. They are readily soluble in respective solvents, and a light yellowish membrane was obtained using the solution casting procedure. These membranes demonstrated admissible mechanical and thermal stabilities, balanced water absorption properties, and reasonable chemical stability. The surface phase (SAXS, AFM) and bulk phase (TEM) morphological analysis proved the well-separated phase morphology. The BABPSSH-90 displayed a proton conductivity of 104 mS cm(-1) at 90 degrees C$$ {}<^>{{}<^>{\circ}}\mathrm{C} $$.