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

Abstract

To attempt the realization of a highly piezoelectric polymer film, we used an oriented poly(-benzyl-L-glutamate) (PBLG) film that was cast from chloroform solution under the strong magnetic field induced by a generation apparatus using a superconducting magnet. First, the orientation of the PBLG principal chain in the film was observed macroscopically by polarizing microscopy (POM), and it was found that the orientation of the principal chain differed in each region. Then, in order to observe each region, using our original apparatus, the birefringence (retardation) and optical axis were measured at 100 m pitch/point-to-point, and a cm-order region with high retardation was found. We then cut off a small piece from this region of the PBLG film and evaluated the shear piezoelectric constant. A large shear piezoelectric constant of 18 pC/N was found in the small piece. Also, the PBLG film was investigated by atomic force microscopy (AFM). We found a characteristic slender structure in the region with a high macroscopic shear piezoelectric constant. Furthermore, the piezoelectric motion due to its shear piezoelectricity in the region was investigated microscopically by piezoresponse force microscopy (PFM), which successfully enabled the direct observation of the piezoelectric displacement due to its shear piezoelectricity in one direction in the entire region with the characteristic slender structure. On the basis of these results, we speculate that the principal chain was highly oriented and crystallized in the region with the characteristic slender structure, resulting in a large shear piezoelectric constant in the region. #

Sensing Using Piezoelectric Chiral Polymer Fiber

“…An axis-oriented PLLA fiber with a drawing ratio of 10 and a diameter of 10 m was obtained by a high-speed spinning process. [11][12][13]18,19) Then, the PLLA fiber was annealed at 105 C for 1 h and quenched. 15,16) Finally, it was subjected to a supercritical CO 2 (s-CO2) treatment to change its highorder structure, thus improving its piezoelectricity.…”

Improvement of Piezoelectricity of Poly(L-lactide) Film by Using Acrylic Symmetric Block Copolymer as Additive

“…2) Furthermore, a one-to-one correspondence has not been found between the macro-piezoelectric properties and the crystal characteris-tics. 1,2,[21][22][23][24] It can be seen that a PLLA film contains complex higher-order structures at various scales. 2,[22][23][24][25] Figure 2 shows different types of higher-order structures of PLLA in increasing order of size from a single-chain molecule to a macroscopic film, including crystalline and amorphous regions and a PLLA crystal.…”

“…1,2,[21][22][23][24] It can be seen that a PLLA film contains complex higher-order structures at various scales. 2,[22][23][24][25] Figure 2 shows different types of higher-order structures of PLLA in increasing order of size from a single-chain molecule to a macroscopic film, including crystalline and amorphous regions and a PLLA crystal. The existence of these complex higher-order structures in the PLLA film is the reason why the piezoelectric constant of PLLA is lower than those of conventional piezoelectric ceramics.…”

“…2) As a result, the piezoelectricity of the PLLA film is reduced. 1,2,4,5,21,22) Therefore, in general, additives have not been adopted in the fabrication process of PLLA films with high piezoelectricity even though their impact resistance is insufficient for practical use. 1,2) On the other hand, research on the modification of mechanical properties through changing the higher-order structure by the addition of additives to PLLA has progressed and many achievements have been reported.…”