Stretchable Self-Healing Polymeric Dielectrics Cross-Linked Through Metal–Ligand Coordination

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• 作者：Ying-Li Rao ; Alex Chortos ; Raphael Pfattner ; Franziska Lissel ; Yu-Cheng Chiu ; Vivian Feig ; Jie Xu ; Tadanori Kurosawa ; Xiaodan Gu ; Chao Wang ; Mingqian He ; Jong Won Chung ; Zhenan Bao
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：138
• 期：18
• 页码：6020-6027
• 全文大小：697K
• 年卷期：0
• ISSN：1520-5126

文摘

A self-healing dielectric elastomer is achieved by the incorporation of metal–ligand coordination as cross-linking sites in nonpolar polydimethylsiloxane (PDMS) polymers. The ligand is 2,2′-bipyridine-5,5′-dicarboxylic amide, while the metal salts investigated here are Fe²⁺ and Zn²⁺ with various counteranions. The kinetically labile coordination between Zn²⁺ and bipyridine endows the polymer fast self-healing ability at ambient condition. When integrated into organic field-effect transistors (OFETs) as gate dielectrics, transistors with FeCl₂ and ZnCl₂ salts cross-linked PDMS exhibited increased dielectric constants compared to PDMS and demonstrated hysteresis-free transfer characteristics, owing to the low ion conductivity in PDMS and the strong columbic interaction between metal cations and the small Cl^– anions which can prevent mobile anions drifting under gate bias. Fully stretchable transistors with FeCl₂-PDMS dielectrics were fabricated and exhibited ideal transfer characteristics. The gate leakage current remained low even after 1000 cycles at 100% strain. The mechanical robustness and stable electrical performance proved its suitability for applications in stretchable electronics. On the other hand, transistors with gate dielectrics containing large-sized anions (BF₄^–, ClO₄^–, CF₃SO₃^–) displayed prominent hysteresis due to mobile anions drifting under gate bias voltage. This work provides insights on future design of self-healing stretchable dielectric materials based on metal–ligand cross-linked polymers.