High strength and high breaking load of single electrospun polyimide microfiber from water soluble precursor

Electrospun polyimide (PI) nanofibers possessed high tensile strength (δ), but the breaking load (BL) is very small. It is also a challenge to prepare electrospun PI microfibers from the PAA precursor in high boiling point solvents. In this work, PI microfibers with diameter more than 2 μm were prepared from their PAA-salt in water mixed with low boiling point solvent, such as ethanol. The single electrospun PI microfiber (S-EPIMF) showed excellent mechanical properties with BL, δ, modulus and tensile strain of 4872 μN, 1064 MPa, 5.6 GPa and 15.7%, respectively. The high BL allows a single electrospun PI microfiber even be able to hold a 0.5 g metal ring. The superior mechanical properties of the electrospun PI microfibers could be attributed to the high molecular orientation and crystallinity in the fibers, and the high BL is due to the large diameter of the electrospun PI microfibers.