Piezoelectric electrospun polyacrylonitrile with various tacticities

Electrospinning of urea clathrate polymerized polyacrylonitrile (PAN) with isotacticity 25% and 52% was achieved in N,N-dimethylformamide (DMF) at room temperature. Although the molecular weights of the 25% and 52% were found to be comparable by size exclusion chromatography, creation of uniform nanofibers with comparable diameters (average of ~450 nm) required concentrations of 5 % w/v and 3.5% w/v, respectively. X-ray diffraction (XRD) analysis demonstrated that the polymer retained semicrystalline structure and suggested that crystallinity was correlated with increasing isotacticity. Fourier transform infrared spectroscopy (FTIR) also confirmed increased crystallinity as compared to commercially purchased free-radical polymerized PAN due to a shift in the ~1250 cm^?1 methine peak. Periodic semistatic normal load piezoelectric testing of the electrospun isotactic PAN samples also exhibited an average of ~30% of the piezoelectric response of electrospun (65:35) poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE), a current gold standard for piezoelectric polymers, whereas commercially purchased free-radical polymerized PAN exhibited no observable piezoelectric response. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47530.