(196ab) Fabrication and Structural Analysis of Nanofibers Made By Syndiotactic Polypropylene with Ethylene-Comonomer Units

Syndiotactic polypropylene with a small amount of ethylene comonomer (sPPEt) possesses an excellent elasticity [1]. In this study, the sPPEts with different ethylene comonomer compositions were synthesized and the fabrication of sPPEt nanofibers was attempted using the electrospinning (ES) method. sPPEt copolymers with different ethylene compositions were successfully fabricated into nanofiber membranes by electrospinning when using a mixture of methyl-cyclohexane/DMF/acetone (8:1:1) as an electrospinning solvent, resulting in thin fiber diameters: 730 nm for the sPPEt copolymer with the ethylene composition of 2 mol%, 324 nm for that with the ethylene composition of 10 mol%, and 467 nm for that with the ethylene composition of 15 mol%. However, the sPPEt copolymer with the ethylene composition of 25 mol% could not form fibers. The morphology of the electrospun sPPEt nanofibers was analyzed by the scanning electron microscopy (SEM). The electrospun nanofibers using sPPEt with the lower ethylene composition (2 mol%) had rough surface, whereas the sPPEt nanofibers with relatively higher ethylene compositions of 10 mol% and 15 mol% had smooth surfaces. The smooth surface of the sPPEt nanofibers with larger ethylene compositions could be due to the suppression of the gelation of the sPPEt solutions. The electropun sPPEt nanofibers were also analyzed by the Fourier-transfer infrared spectroscopy (FTIR) and the X-ray diffraction (XRD) measurements. From the FTIR analysis, it was revealed that the ratio of the trans-planar/helical conformations (T/R ratio) of the electrospun sPPEt nanofibers was higher than that of the simple sPPEt cast films regardless of the ethylene compositions in sPPEt. [1] Claudio De Rosa, Finizia Auriemma, Mechanical properties of syndiotactic propylene-ethylene copolymers, Macromolecules, Vol. 39, 249-256 (2006).