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

J Am Chem Soc. 2016 May 11;138(18):6020-7. doi: 10.1021/jacs.6b02428. Epub 2016 May 3.

Abstract

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 Fe(2+) and Zn(2+) with various counteranions. The kinetically labile coordination between Zn(2+) 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 2,2'-Dipyridyl
  • Chlorides / chemistry
  • Cross-Linking Reagents
  • Dimethylpolysiloxanes / chemistry
  • Elasticity
  • Electronics
  • Ferrous Compounds / chemistry
  • Ligands
  • Metals / chemistry*
  • Polymers / chemistry*
  • Zinc Compounds / chemistry

Substances

  • Chlorides
  • Cross-Linking Reagents
  • Dimethylpolysiloxanes
  • Ferrous Compounds
  • Ligands
  • Metals
  • Polymers
  • Zinc Compounds
  • 2,2'-Dipyridyl
  • baysilon
  • zinc chloride
  • ferrous chloride