Ferroelectricity polyurea

Hattori, X, Takahashi, Y, lijima, M., Fukada, E., 1996. Piezoelectric and ferroelectric properties of polyurea-5 thin films prepared by vapor deposition polymerization. J. Appl. Phys. 79,1713-1721. 

Polyurea was shown to display ferroelectric properties after formation by vapor deposition polymerization [14,33,44-48]. The orientation of urea bonds (NH—CO—NH) with a dipole moment of 4.9 D produced a large residual polarization (Fig. 5) [33]. 

An AC field with a period of 100 s and an amplitude of 100 V, applied to polyurea films 1 tm thick, was capable of aligning the urea dipoles. A ferroelectric hysteresis loop as observed in Fig. 3 was observed for the poly urea thin films [47,48]. A remanent polarization of 1 /aC/cm and a coercive field strength ( ,.) of 100 MV/m were observed for such polyurea films [9]. The tensile piezoelectric... 

Fig. 5 The ratio of the relevant component of the piezoelectric coefficient d and the respective polarization is plotted vs. the reciprocal of the respective elastic modulus Y (i.e., the relevant component of the elastic compliance). From left to right Literature data for inorganic ferroelectrics squares) barium titanate (BaTiOs), lead zirconate titanate (PZT), and lead zirconate niobate (PZN). Ferroelectric polymers triangles) polyamide-11 (PA-11), poly(vinylidene cyanide-vinyl acetate) (P(VDCN-VAc)), polyurea-5, poly(vinylidene fiuoride (PVDF)), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), and poly(vinylidene-hexafiuoropropylene) (P(VDF-HFP)). Polymer ferroelectrets circles) cellular polypropylene (cellular-PP) and tubular-channel poly (fluoro-ethylene-propylene) (FEP) (Qiu et al. 2014)...

In semicrystalline dipole electrets, polar crystallites are present in addition to the polar amorphous phase (Fig. 2b). In die technically most interesting semicrystalline dipole electrets such as polyvinyhdene fluoride (PVDF) and its copolymers with trifluoro ethylene (P(VDF-TrFE)) (Lovinger 1983) or hexafluoropropylene (P(VDF-HFP)), odd Nylons 7 and 11, polyureas, polyureflianes (PU), and some liquid crystalline polymers, the crystallites are ferroelectric (Vasudevan et al. 1979 Hattori et al. 1996). The terpolymer poly(vinyhdene-fluoride-trifluoroethylene— chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) has been shown to have relaxor ferroelectric properties as the CTFE group destabilizes die long-range order of the ferroelectric phase (Xu et al. 2001). 

T. Sytdu, M. Ohtani, S. Ihsalm. and M Inugaki. Ferroelectric behavior on polyamides and polyureas with odd number of CH2 groups. Sen-i-GMai Symp. Preprints, 1992, p. B97. 

S. Iksaka, K. Ohisbi. H. S. Nalwa, T. Watanabe, and S. Miyata. Ferroelectric polarization reversal stabilized by hydrogen bonding in N-phenylated aromatic polyurea. Polymer J.. 26 505 (1994V... 

This chapter describes the most recent developments in pyroelectricity, piezoelectricity, and ferroelectricity of polyurea and polythiourea. 

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