Ferroelectric switching in spin-coated nylons 11 and 12

Here, we investigate the correlation between the crystal structures and the ferroelectric switching by a sinusoidal alternative electric field for spin-coated nylon 11 films as an odd nylon and for nylon 12 as an even nylon. These spin-coated nylons afforded thin films with thicknesses ranging from 101 to 125 nm. The obtained thin films were subjected to melt-quenching, melt-cooling down, annealing-quenching, or annealing-cooling down. These processes were notably related to the resulting crystal structures. In particular, the crystal structures involving twisted bonds in the molecular chains were significantly related to ferroelectricity in both nylon 11 and nylon 12. Namely, the vector component of the amide dipole moments is transverse to the direction of the molecular chains, which is induced by the presence of more twisted bonds and is significantly related to the remanent polarization P-r for both nylons. In nylon 11, the hydrogen bonding interaction between the intermolecular amide dipole moments in the alpha and delta crystal forms was weakened by the existence of more twisted bonds. In nylon 12, the nonpolar gamma crystal form was transformed to a polarizable gamma' crystal form because of the existence of more twisted bonds. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48438.