Four kinds of piezoelectric polymers are introduced. Submicron thin fi
lms of polyurea are prepared by vapor deposition polymerization. Poled
films of aromatic polyurea exhibit the piezoelectric constant d(31) =
20 pC/N, which is almost independent of temperature in the range of 1
00 to 200 degrees C. Aliphatic polyureas show a ferroelectric hysteres
is with a coercive field of about 100 MV/m. Single crystalline films o
f a copolymer of vinylidene fluoride and trifluoroethylene were prepar
ed by annealing elongated films at a paraelectric temperature range av
oiding the side surface contacts. No lamella structures were present a
nd the crystallinity was near 100%. The large electromechanical coupli
ng factors k(33) = 0.3 and k(31) = 0.1 were observed. A large electros
trictive constant R = 2.6 x 10(-17) m(2)/V-2 was observed for polyuret
hane. With a de bias field of 15 MV/m, a piezoelectric constant of d(3
3) = 600 pC/N was obtained, which was larger than that of PZT. A shear
piezoelectric constant d(14) = -10 pC/N was obtained for oriented fil
ms of poly-L-lactic acid, which were optically active and biodegradabl
e. After poling, this polymer showed the tensile piezoelectricity and
pyroelectricity.