Ferroelectric switching in spin‐coated nylons 11 and 12

Abstract

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 α and δ crystal forms was weakened by the existence of more twisted bonds. In nylon 12, the nonpolar γ crystal form was transformed to a polarizable γ' crystal form because of the existence of more twisted bonds.

Piezoelectric polymers: theory, challenges and opportunities

“…The piezoelectric e 31 coefficient was shown to increase with draw ratio, also shown in Figure 4(b), and this was attributed to the increase in elastic modulus that occurs as a consequence of drawing [9]. Even in recent work, studies are still performed either on drawn [71] or undrawn [70,83] samples.…”

Ferroelectric performance of nylons 6-12, 10-12, 11-12, and 12-12

“…However, in recent studies, the pseudohexagonal g crystal form is a metastable crystalline phase with a twisted chain conformation and weakened hydrogen bonds, which enables electric-eld-induced ferroelectricity. [24][25][26] From this discussion, the observed ferroelectric switching of the MQ even-even-numbered and odd-even-numbered nylon samples seemed to be caused by the polarization of the g crystal form.…”

“…However, in recent studies of nylon 12 and nylon 6, the melt-quenched and stretched, meltquenched, annealed, and stretched samples showed electric-eld-induced ferroelectric switching behaviors. [24][25][26] It is considered that the ferroelectricity of even-numbered nylons was caused by weak hydrogen bonds originating from multiple twisted chain conformations in pseudohexagonal g crystal structures. From the above discussion, it is clear that the polar crystalline structure is not a prerequisite for ferroelectric performance in nylon samples.…”

Piezoelectric Properties of Electrospun Polymer Nanofibers and Related Energy Harvesting Applications

“…They found that ferroelectric responses were mainly attributed to the lower degree of hydrogen bond in the twisted chain structure in nylon nanofibers. [56] In 2020, Anwar et al fabricated piezoelectric 𝛿-phase nylon 11 nanofibers by ES nylon 11 in trifluoroacetic acid solution. [57] They found that the 𝛿-phase nylon nanofibers exhibited the highest electrical activity, generating up to 6 V under a mechanical vibration.…”

“…They found that ferroelectric responses were mainly attributed to the lower degree of hydrogen bond in the twisted chain structure in nylon nanofibers. [ 56 ]…”