@article{StoyanovKolloscheRisseetal.2011,
  author    = {Stoyanov, Hristiyan and Kollosche, Matthias and Risse, Sebastian and McCarthy, Denis N. and Kofod, Guggi},
  title     = {Elastic block copolymer nanocomposites with controlled interfacial interactions for artificial muscles with direct voltage control},
  series = {Soft matter},
  volume    = {7},
  journal   = {Soft matter},
  number    = {1},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1744-683X},
  doi       = {10.1039/c0sm00715c},
  pages     = {194 -- 202},
  year      = {2011},
  abstract  = {Soft, physically crosslinking, block copolymer elastomers were filled with surface-treated nanoparticles, in order to evaluate the possibility for improvement of their properties when used as soft dielectric actuators. The nanoparticles led to improvements in dielectric properties, however they also reinforced the elastomer matrix. Comparing dielectric spectra of composites with untreated and surface-treated particles showed a measurable influence of the surface on the dielectric loss behaviour for high filler amounts, strongly indicating an improved host-guest interaction for the surface-treated particles. Breakdown strength was measured using a test bench and was found to be in good agreement with the results from the actuation measurements. Actuation responses predicted by a model for prestrained actuators agreed well with measurements up to a filler amount of 20\%(vol). Strong improvements in actuation behaviour were observed, with an optimum near 15\%(vol) nanoparticles, corresponding to a reduction in electrical field of 27\% for identical actuation strains. The use of physically crosslinking elastomer ensured the mechanical properties of the matrix elastomer were unchanged by nanoparticles effecting the crosslinking reaction, contrary to similar experiments performed with chemically crosslinking elastomers. This allows for a firm conclusion about the positive effects of surface-treated nanoparticles on actuation behavior.},
  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}
}
@article{KofodRisseStoyanovetal.2011,
  author    = {Kofod, Guggi and Risse, Sebastian and Stoyanov, Hristiyan and McCarthy, Denis N. and Sokolov, Sergey and Kr{\"a}hnert, Ralph},
  title     = {Broad-spectrum enhancement of polymer composite dielectric constant at ultra low volume fractions of silica-supported copper nanoparticles},
  series = {ACS nano},
  volume    = {5},
  journal   = {ACS nano},
  number    = {3},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1936-0851},
  doi       = {10.1021/nn103097q},
  pages     = {1623 -- 1629},
  year      = {2011},
  abstract  = {A new strategy for the synthesis of high permittivity polymer composites is demonstrated based on well-defined spatial distribution of ultralow amounts of conductive nanoparticles. The spatial distribution Was realized by immobilizing Cu nanoparticles within the pore system of Alia microspheres, preventing direct contact between individual Cu particles. Both Cu-loaded and unloaded silica microspheres were-then used as fillers in polymer composites prepared with thermoplastic SEBS rubber is the matrix. With a metallic Cu content of about 0.26 vol \% In the compoilte, a relative increase of 94\% In real permittivity was obtained. No Cu-induced relaxations were observed in the dielectric spectrum within the studied frequency range of 0.1 Hz to 1 MHz. When related to the amount of conductive nanoparticles, the obtained composites achieve the highest broad spectrum enhancement of permittivity ever reported for a polymer based composite.},
  language  = {en}
}