Fabrication and structural analyses of electrospun syndiotactic propylene-ethylene copolymer nanofibers

Fabrication and structural characterization of syndiotactic propylene-ethylene (sPPEt) copolymer nanofibers were conducted. When using a mixture of methylcyclohexane/DMF/acetone (8:1:1 (wt/wt)) as a solvent, semi-crystalline sPPEt copolymers with ethylene compositions ranging from 1.9 to 11.8 mol% were successfully fabricated into nanofibers via electrospinning. Copolymerization of sPP with ethylene significantly promoted the formation of thinner and smoother nanofibers by suppressing gelation of the spinning solution, thereby enhancing the electrospinnability of the sPP-based copolymer. FTIR and X-ray structural analyses on sPPEt nanofiber membranes revealed that the electrostatic stretching force during the electrospinning process led to a larger proportion of syndiotactic propylene units in the trans-planar conformation and the resulting formation of mesomorphic form crystals, similar to what has been observed during mechanical stretching and subsequent relaxation.