Recent developments of polar piezoelectric polymers

Abstract

Following the extensive studies on the piezoelectric, pyroelectric and ferroelectric properties of polyvinylidene fluoride and its copolymers, a vast number of polymers were investigated for these properties. Piezoelectric thin films of polyurea were prepared by vapor deposition polymerization in vacuum and stable up to 200 o C. Piezoelectric odd nylon was characterized by the field induced rotation of amide dipoles in the molecular sheet crystalline structure. Completely amorphous vinylidene cyanide copolymers produced a remanent polarization proportional to the large dielectric relaxation strength during poling. Drawn films of polylactic acid exhibited the large shear piezoelectricity due to the crystalline structure of helical molecules, however, a remnant polarization was also produced by poling at high temperatures. Various polymers containing dipolar groups of carbonyl, urethane, urea and thiourea bonds were poled and their ferroelectric hysteresis was observed. Application of magnetic field as high as 10 Tesla to the liquid crystalline state of helical molecules of poly-γ-benzyl-L-glutamate during film formation resulted in a very high shear piezoelectric constant 26 pC/N. Unprecedented high piezoelectric constant such as 1000 pC/N was found in the highly hydrated cornea membrane consisting of collagen fibrils.

Recent Progress on Piezoelectric, Pyroelectric, and Magnetoelectric Polymer‐Based Energy‐Harvesting Devices

“…The dipolar moment magnitude is 4.9 and 3.4 D (debyes) for urea and amide bond, respectively . The piezoelectric strain constant for nylon‐11 increases from d 31 = 2 pC N −1 at 20 °C to 14 pC N −1 at 180 °C . Its dielectric constant is near 3 at 25 °C, and increases with increase in temperature…”

“…There are biomaterials approved by the Food and Drug Administration (FDA) federal agency and have been extensively tested for scaffold materials as bioerodible materials due to good controllable biodegradability and relatively easy processability . The piezoelectric constant of PLLA is d 14 = −10 pC N −1 , with a T g at 64 °C, T C at 107 °C, and T m at 171 °C …”

“…Polyureas are a hard resin that exhibits excellent chemical, thermal, and organic solvent resistance . They are formed by the rapid reaction of isocyanates and amines, showing microphase separation between hard and soft domains, with high and low T g , respectively.…”

Radio frequency functional capacitors made of all-organic composites of thiourea in field-responsive polymers

“…[3][4][5] Similarly, through supramolecular assembly of nonpolar conjugated molecules, considerable ferroelectric response can now be obtained in cocrystals of low molecular weight organic compounds. Two field-responsive polymer matrices with polyvinylidene fluoride ͑PVDF͒ and -conjugated tris͑8-hydroxyquinoline͒aluminum͑III͒ inclusions were used to fabricate six model high-capacitor devices.…”

Piezoelectric Characteristics of Poly(γ-benzyl-L-glutamate) Film Oriented under Strong Magnetic Field

“…[1][2][3][4][5][6][7] On the other hand, in general, a polymer is a soft material; thus, a polymer film is highly flexible, thin, and light compared with inorganic materials. 8,9) Thus, in the practical application to an actuator, polymers are advantageous over inorganic materials.…”