Ceramic nanotubes-based elastomer composites for applications in electromechanical transducers

Titanium dioxide-based nanoparticles with nanotube morphology were synthesised and used in low fractions (2 and 5 wt%) as dielectric permittivity enhancers for high molecular weight polydimethylsiloxane matrix (M-n = 350,000 g mol(-1)). In order to ensure good dispersability in, and compatibility with the silicone matrix, the filler was treated with hexamethyldisilazane. The polymer composites were processed as films and stabilized by condensation of the chain ends with a trifunctional silane, resulting in lowdensity cross-linking elastomers. The films were characterized for morphology, dielectric and mechanical behavior. The evaluated properties were compared with those measured in similar conditions for a pure cross-linked silicone matrix and a commercial dielectric elastomer taken as references. The results indicated an increase in dielectric permittivity (up to 33%), as a result of filler incorporation without significantly damaging dielectric strength (>60 V mu m(-1)) and mechanical properties (elastic modulus as low as 0.4MPa and high strains at break up to 600%). Electromechanical measurements revealed the best performance in actuation for the composite containing 2 wt% nanotubes (4.2% lateral strain at 40 V.mu m(-1)). Initial tests for energy harvesting performed with dielectric elastomer generators built with the same material sandwiched between two highly compliant electrodes yielded promising energy conversion efficiency (up to 8.84% at 2.5 V.mu m(-1)). (C) 2017 Elsevier Ltd. All rights reserved.