Self-assembled aromatic polyamide nanofibers with trifluoromethyl groups via precipitation polymerization

Aromatic polyamide nanofibers with trifluoromethyl groups were prepared from a diacid chloride and a diamine in dioxane solution with a water content of 9 vol%, via precipitation polymerization. The resulting nanofibers had an average diameter of approximately 50 nm and were highly intertwined. The reaction solution exhibited high viscosity, resulting in the formation of a gel, due to strong interactions between the polymer and the solvent. It was determined that, during the fiber formation process, the product in the reaction solution transitioned from particles into fibers with a concurrent increase in molecular weight. As the reaction time was prolonged following the formation of the fibers, both the polymerʹs degree of crystallinity and the hydrogen bonding between polymer chains increased, while the morphology of the product became less regular.