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Enhancement of dielectric permittivity and electromechanical response In silicone elastomers

Molecular grafting of organic dipoles to the macromolecular network
: Kussmaul, B.; Risse, S.; Kofod, G.; Wache, R.; Wegener, M.; McCarthy, D.N.; Krüger, H.; Gerhard, R.


Advanced Functional Materials 21 (2011), Nr.23, S.4589-4594
ISSN: 1616-301X
ISSN: 1616-3028
Fraunhofer IAP ()

A novel method is established for permittivity enhancement of a silicone matrix for dielectric elastomer actuators (DEAs) by molecular level modifications of the elastomer matrix. A push-pull dipole is synthesized to be compatible with the silicone crosslinking chemistry, allowing for direct grafting to the crosslinker molecules in a one-step film formation process. This method prevents agglomeration and yields elastomer films that are homogeneous down to the molecular level. The dipole-to-silicone network grafting reaction is studied by FTIR. The chemical, thermal, mechanical and electrical properties of films with dipole contents ranging from 0 wt% to 13.4 wt% were thoroughly characterized. The grafting of dipoles modifies the relative permittivity and the stiffness, resulting in the actuation strain at a given electrical field being improved by a factor of six.