Understanding ferroelectric performances of spin-coated odd-odd nylon thin films

摘要

Ferroelectric properties of organic odd-odd nylon spin-coated thin films are investigated. Nylon 11-11, 9-13, and 11-13 are prepared by melt polymerization of the nylon salt consisting of the corresponding dicarboxylic acid and diamine. The obtained nylon is spin coated to obtain thin films with the thicknesses in the range of 85-108nm. After spin coating, the sample films are subjected to several thermal history procedures, namely the films are either melt quenched or thermally annealed at various temperatures. The melt-quenched films are in the crystal phase that is directly related to the ferroelectricity of the sample thin films. Enhanced ferroelectricity is measured for the sample films that are thermally annealed at 165 degrees C. The remanent polarization is significantly affected by the crystallite size. Ferroelectric switching of the thin films is studied by applying a sinusoidal voltage with the frequencies of 1, 10, 100, 1k, and 10kHz. The switching speed is evaluated from the full width at half-maximum of the switching current. A switching speed of 4.7x10(3)s(-1) (switching time of 210s) is measured for 1 kHz switching. The remanent polarization is strongly decreased by increasing the switching frequency, whereas the coercive field is increased. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47595.