@article{KussmaulRisseWegeneretal.2012,
  author    = {Kussmaul, Bj{\"o}rn and Risse, Sebastian and Wegener, Michael and Kofod, Guggi and Kr{\"u}ger, Hartmut},
  title     = {Matrix stiffness dependent electro-mechanical response of dipole grafted silicones},
  series = {Smart materials and structures},
  volume    = {21},
  journal   = {Smart materials and structures},
  number    = {6},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0964-1726},
  doi       = {10.1088/0964-1726/21/6/064005},
  pages     = {6},
  year      = {2012},
  abstract  = {The properties of dielectric elastomer actuators can be optimized by modifying the dielectric or mechanical properties of the dielectric elastomer. This paper presents the simultaneous control of both dielectric and mechanical properties, in a silicone elastomer network comprising cross-linker, chains and grafted molecular dipoles. Chains with two different molecular weights were each combined with varying amounts of grafted dipole. Chemical and physical characterization showed that networks with stoichiometric control of cross-linking density and permittivity were obtained, and that longer chain lengths resulted in higher electrical field response due to the reduction in cross-linking density and correspondingly in mechanical stiffness. Both actuation sensitivities were enhanced by 6.3 and 4.6 times for the short and long chain matrix material, respectively.},
  language  = {en}
}
@article{KussmaulRisseKofodetal.2011,
  author    = {Kussmaul, Bjoern and Risse, Sebastian and Kofod, Guggi and Wache, Remi and Wegener, Michael and McCarthy, Denis N. and Kr{\"u}ger, Hartmut and Gerhard, Reimund},
  title     = {Enhancement of dielectric permittivity and electromechanical response in silicone elastomers molecular grafting of organic dipoles to the macromolecular Network},
  series = {Advanced functional materials},
  volume    = {21},
  journal   = {Advanced functional materials},
  number    = {23},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1616-301X},
  doi       = {10.1002/adfm.201100884},
  pages     = {4589 -- 4594},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}