Development of High Dielectric Electrostrictive PVDF Terpolymer Blends for Enhanced Electromechanical Properties

Il Jin Kim; Kie Yong Cho; Eunji Kim; Young Je Kwon; Min Young Shon; Bo-In Park; Seunggun Yu; Jin Hong Lee

doi:10.3390/nano11010006

Development of High Dielectric Electrostrictive PVDF Terpolymer Blends for Enhanced Electromechanical Properties

Nanomaterials (Basel). 2020 Dec 22;11(1):6. doi: 10.3390/nano11010006.

Authors

Il Jin Kim¹, Kie Yong Cho^{2

3}, Eunji Kim¹, Young Je Kwon³, Min Young Shon^{2

3}, Bo-In Park⁴, Seunggun Yu⁵, Jin Hong Lee¹

Affiliations

¹ School of Chemical Engineering, Pusan National University, Busan 46421, Korea.
² Department of Industrial Chemistry, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48513, Korea.
³ Division of Applied Chemical Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48513, Korea.
⁴ Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.
⁵ Insulation Materials Research Center, Korea Electrotechnology Research Institute (KERI), Changwon 51543, Korea.

Abstract

Electroactive polymers with high dielectric constants and low moduli can offer fast responses and large electromechanical strain under a relatively low electric field with regard to theoretical driving forces of electrostriction and electrostatic force. However, the conventional electroactive polymers, including silicone rubbers and acrylic polymers, have shown low dielectric constants (ca. < 4) because of their intrinsic limitation, although they have lower moduli (ca. < 1 MPa) than inorganics. To this end, we proposed the high dielectric PVDF terpolymer blends (PVTC-PTM) including poly(vinylidene fluoride-trifluoroethylene-chlorofluoro-ethylene) (P(VDF-TrFE-CFE), PVTC) as a matrix and micelle structured poly(3-hexylthiophene)-b-poly(methyl methacrylate) (P3HT-b-PMMA, PTM) as a conducting filler. The dielectric constant of PVTC-PTM dramatically increased up to 116.8 at 100 Hz despite adding only 2 wt% of the polymer-type filler (PTM). The compatibility and crystalline properties of the PVTC-PTM blends were examined by microscopic, thermal, and X-ray studies. The PVTC-PTM showed more compatible blends than those of the P3HT homopolymer filler (PT) and led to higher crystallinity and smaller crystal grain size relative to those of neat PVTC and PVTC with the PT filler (PVTC-PT). Those by the PVTC-PTM blends can beneficially affect the high-performance electromechanical properties compared to those by the neat PVTC and the PVTC-PT blend. The electromechanical strain of the PVTC-PTM with 2 wt% PTM (PVTC-PTM2) showed ca. 2-fold enhancement (0.44% transverse strain at 30 V_pp μm^-1) relative to that of PVTC. We found that the more significant electromechanical performance of the PVTC-PTM blend than the PVTC was predominantly due to the electrostrictive force rather than electrostatic force. We believe that the acquired PVTC-PTM blends are great candidates to achieve the high-performance electromechanical strain and take all benefits derived from the all-organic system, including high electrical breakdown strength, processibility, dielectrics, and large strain, which are largely different from the organic-inorganic hybrid nanocomposite systems.

Keywords: PVDF; actuators; electromechanical properties; high dielectric constant; polymer composites.