Fabrication and Characterization of Fluorine-Containing Aromatic Polyamide Nanofiber Mats

Aromatic polyamide nanofibers with trifluoromethyl (CF3) groups were fabricated from 4,4'-diphenyldicarbonyl chloride and 2,2'-bis(trifluoromethyl) benzidine in a dioxane solution containing water using a precipitation polymerization method. The morphology of the fibers obtained depended on the water content in the reaction solvent and the monomer concentration. The product prepared in the dioxane solution with a water content of 9 vol% was composed of intimately-interconnected fibers with a diameter of ca. 50 nm, and showed a high affinity for the reaction solvent to form a gel. The product showed excellent thermal stability, in which the thermal decomposition temperature at 5% weight loss was 496(circle)C. Also, it was soluble in sulfuric acid, N-methylpyrrolidone and dimethyl acetoamide but was insoluble in many other solvents, indicating excellent chemical resistance. The products obtained before and after drying showed different swelling behaviors in poor solvents. The specific surface area of the product was found to be affected by the solvent treatment before drying.