A research group led by Prof. Li Runwei at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS) has proposed a “slight crosslinking” method that imparts elastic recovery to ferroelectric materials.
The study was recently published in the journal Science.
Importance of Ferroelectric Materials
Ferroelectric materials are very useful for applications such as data storage and processing, sensing, energy conversion, and optoelectronics, etc., making them highly desirable in mobile phones, tablets, and other electronic devices for everyday use.
After stress is relieved, however, conventional ferroelectric materials exhibit poor elastic recovery—typically less than 2%, and thus tend to be either brittle (ferroelectric ceramics) or plastic (ferroelectric polymers).
The ferroelectric properties of these materials are mainly due to their crystalline regions, which lack intrinsic elasticity.
The “Slight Crosslinking” Solution
To solve the dilemma of ferroelectric response and elastic recovery, the researchers developed a precise “slight crosslinking” method.
By using poly(vinylidene fluoride–trifluoroethylene) as the matrix material and soft-long-chain polyethylene oxide diamine as the crosslinker, the researchers established a network structure in linear ferroelectric polymers.
By precisely controlling the crosslinking density at 1–2%, the crosslinked ferroelectric film mainly exhibited a β-phase crystalline structure and was uniformly dispersed in the crosslinked polymer network.
Under stress, the network structure can evenly distribute and bear external forces, thereby mitigating damage to the crystalline regions. Thus, these newly developed ferroelectrics combine elasticity with relatively high crystallinity. Experimental results also showed that the cross-linked film retained a stable ferroelectric response and elastic recovery even under strains up to 70%.
“Based on their study,” said Prof. XIONG Rengen, an internationally renowned expert in ferroelectric materials, “Gao et al. have established a new research direction, elastic ferroelectrics.”
Elastic ferroelectrics such as these, with excellent resistance to mechanical and ferroelectric fatigue, have broad application prospects in wearable electronics and smart healthcare.
Reference: “Intrinsically elastic polymer ferroelectric by precise slight cross-linking” by Liang Gao, Ben-Lin Hu, Linping Wang, Jinwei Cao, Ri He, Fengyuan Zhang, Zhiming Wang, Wuhong Xue, Huali Yang and Run-Wei Li, 3 August 2023, Science.
This work was supported by the National Natural Science Foundation of China, the Zhejiang Province Qianjiang Talent Program, and the K.C. Wong Education Foundation, among others.