Ferroelectric polarization reversal in polyureas with odd number of CH sub(2) groups

Ferroelectric polarization reversal was found in polyureas with an odd number of CH sub(2) groups: polyheptamethyleneurea, polynonamethyleneurea and copoly(heptametylene/nonmethylene urea) (polyurea 79). Remanent polarization as high as 440 mC/m super(2) and coercive field of 28 MV/m were observed in quenched polyurea 79 at 90 degree C. The irreversible dielectric anomaly in a temperature region of crystal transition was shown in the quenched samples. Polyureas with an odd number of CH sub(2) groups are ferroelectrics.