Direct evidence for electrostriction-enhanced piezoelectricity in poly(vinylidene fluoride-co-trifluoroethylene) random copolymers

Abstract

A ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] 52/48 mol.% random copolymer was recently shown to exhibit large piezoelectric responses when properly processed to achieve an extended-chain crystal structure. Although relaxor-like secondary crystals (SCs) within the oriented amorphous fraction (OAF), that is, SC_OAF, was proposed to explain the high direct and converse piezoelectric coefficients in the quenched-stretched-annealed-poled sample (denoted as coP-52/48QSAP), direct structural verification remained unavailable. In this work, we employed in-situ time-resolved small-angle scattering and wide-angle X-ray diffraction to study the nanoscale structural evolution of SC_OAF under mechanical loading. We find that even a small strain up to 5.84% triggered significant lamellar thickening, together with stretching-induced crystallization (i.e., 10% increase in crystallinity) by merging SC_OAF into the poled primary crystal (PC) lamellae. Due to the templating effect from PCs with poled/aligned dipoles, the overall polarization increased. Upon removing the mechanical loading, the lamellar spacing, SC_OAF, and polarization largely recovered, demonstrating the direct piezoelectric effect. These results established direct structural evidence linking reversible SC_OAF crystallization/melting upon mechanical loading/unloading to the giant piezoelectricity of coP-52/48QSAP. The knowledge obtained from this study will provide design principles for engineering next-generation high-performance piezoelectric polymers.

Keywords

direct piezoelectricity / in-situ characterization / poly(vinylidene fluoride-co-trifluoroethylene) / small-angle X-ray scattering / wide-angle X-ray diffraction

References

[1] H. Kawai, Jpn. J. Appl. Phys. 1969, 8, 975.

[2] A. J. Lovinger, Science 1983, 220, 1115.

[3] L. Zhang, S. Li, Z. Zhu, G. Rui, B. Du, D. Chen, Y. Huang, L. Zhu, Adv. Funct. Mater. 2023, 33, 2301302.

[4] X. Qian, X. Chen, L. Zhu, Q. Zhang, Science 2023, 380, eadg0902.

[5] G. Xia, J. Fang, D. Shou, X. Wang, Prog. Mater. Sci. 2024, 146, 101340.

[6] F. Ye, S. Aya, M. Huang, Prog. Polym. Sci. 2025, 170, 102028.

[7] G. Rui, E. Allahyarov, Z. Zhu, Y. Huang, T. Wongwirat, Q. Zou, P. L. Taylor, L. Zhu, Responsive Mater. 2024, 2, e20240002.

[8] M. G. Broadhurst, G. T. Davis, Ferroelectrics 1984, 60, 3.

[9] Y. Huang, G. Rui, Q. Li, E. Allahyarov, R. Li, M. Fukuto, G.-J. Zhong, J.-Z. Xu, Z.-M. Li, P. L. Taylor, L. Zhu, Nat. Commun. 2021, 12, 675.

[10] T. Furukawa, H. Kodama, H. Ishii, S. Kojima, T. Nakajima, W. C. Gan, T. S. Velayutham, W. H. A. Majid, Polymer 2023, 283, 126235.

[11] M. G. Broadhurst, G. T. Davis, J. E. Mckinney, R. E. Collins, J. Appl. Phys. 1978, 49, 4992.

[12] T. Furukawa, J. X. Wen, K. Suzuki, Y. Takashina, M. Date, J. Appl. Phys. 1984, 56, 829.

[13] T. Furukawa, N. Seo, Jpn. J. Appl. Phys. 1990, 29, 675.

[14] F. Li, L. Jin, Z. Xu, S. J. Zhang, Appl. Phys. Rev. 2014, 1, 011103.

[15] H. S. Nalwa, Ed. in Ferroelectric Polymers: Chemistry, Physics, and Applications, Marcel Dekker, New York 1995.

[16] Q. M. Zhang, C. Huang, F. Xia, J. Su, in Electroactive Polymer (EAP) Actuators as Artificial Muscles: Reality, Potential, and Challenges, Vol. PM136 (Ed: Y. Bar-Cohen), 2nd ed., SPIE Press 2004, p. 89 Chapter 4.

[17] X. Chen, H. Qin, X. Qian, W. Zhu, B. Li, B. Zhang, W. Lu, R. Li, S. Zhang, L. Zhu, F. Dominguez Dos Santos, J. Bernholc, Q. Zhang, Science 2022, 375, 1418.

[18] Y. Liu, H. Aziguli, B. Zhang, W. Xu, W. C. Lu, J. Bernholc, Q. Wang, Nature 2018, 562, 96.

[19] Y. Liu, Q. Wang, Adv. Sci. 2020, 7, 1902468.

[20] Y. Liu, B. Zhang, A. Haibibu, W. H. Xu, Z. B. Han, W. C. Lu, J. Bernholc, Q. Wang, J. Phys. Chem. C 2019, 123, 8727.

[21] Y. Wada, R. Hayakawa, Jpn. J. Appl. Phys. 1976, 15, 2041.

[22] Y. Wada, R. Hayakawa, Ferroelectrics 1981, 32, 115.

[23] K. Tashiro, M. Kobayashi, H. Tadokoro, E. Fukada, Macromolecules 1980, 13, 691.

[24] K. Tashiro, H. Tadokoro, Macromolecules 1983, 16, 961.

[25] N. Karasawa, W. A. Goddard, III, Macromolecules 1992, 25, 7268.

[26] G. Rui, Y. Huang, X. Chen, R. Li, D. Wang, T. Miyoshi, L. Zhu, J. Mater. Chem. C 2021, 9, 894.

[27] S. Tasaka, S. Miyata, Ferroelectrics 1981, 32, 17.

[28] I. M. Ward, Mechanical Properties of Solid Polymers, Wiley, New York 1983.

[29] P. Harnischfeger, B. J. Jungnickel, Ferroelectrics 1990, 109, 279.

[30] T. Wongwirat, Z. Zhu, G. Rui, R. Li, P. Laoratanakul, H. He, H. Manuspiya, L. Zhu, Macromolecules 2020, 53, 10942.

[31] Z. Zhu, G. Rui, Q. Li, E. Allahyarov, R. Li, T. Soulestin, F. Domingues Dos Santos, H. He, P. Taylor, L. Zhu, Matter 2021, 4, 3696.

[32] Z. Zhu, G. Rui, R. Li, H. He, L. Zhu, Macromolecules 2021, 54, 9879.

[33] G. Rui, E. Allahyarov, R. Li, P. L. Taylor, L. Zhu, Mater. Horizons 2022, 9, 1992.

[34] G. Rui, E. Allahyarov, H. Zhang, R. Li, S. Zhang, P. Taylor, L. Zhu, Nano Energy 2023, 113, 108590.

[35] Z. Zhu, G. Rui, E. Allahyarov, H. Zhang, R. Li, P. L. Taylor, L. Zhu, Polymer 2025, 325, 128290.

[36] J. Gao, Y. Tang, D. Martella, J. Guo, D. S. Wiersma, Q. Li, Responsive Mater. 2023, 1, e20230008.

[37] S. Ma, P. Xue, Y. Tang, R. Bi, X. Xu, L. Wang, Q. Li, Responsive Mater. 2024, 2, e20230026.

[38] R. Zheng, Y. Wei, Z. Zhang, Z. Wang, L. Ma, Y. Wang, L. Huang, Y. Lu, Responsive Mater. 2023, 1, e20230017.

[39] R. Lan, X. Hu, J. Chen, X. Zeng, X. Chen, T. Du, X. Song, H. Yang, Responsive Mater. 2024, 2, e20230030.

[40] J. Jeon, D. Bukharina, M. Kim, S. Kang, J. Kim, Y. Zhang, V. Tsukruk, Responsive Mater. 2024, 2, e20230032.

RIGHTS & PERMISSIONS

2026 The Author(s). Responsive Materials published by John Wiley & Sons Australia, Ltd on behalf of Southeast University.