Thin polyurea-5 films were prepared by vapor-deposition polymerization
of 1,5-diaminopentane and 1,5-diisocyanatepentane. In order to invest
igate the ferroelectric properties of polyurea-5, we measured switchin
g behavior. Switching phenomena were observed for the polymer thin fil
ms at room temperature. It was found that the switching time depends o
n the applied electric field E, and that the amount of reversed polari
zation is nearly independent of E. The results clearly revealed charac
teristics of ferroelectric switching phenomena. As a result; we obtain
ed a residual polarization of about 20 mC/m(2) at room temperature. We
found also that the switching time is long, and that the shape of swi
tching curves is broad, compared to those of typical ferroelectric pol
ymers, vinylidene fluoride and trifluoroethylene copolymers.