Elastomeric actuators based on ethylene-vinyl acetate and carbon nanotubes

Abstract

The development of new types of visual-aid tablet for visually impaired people requires the development of cheap, but still very effective photoactuating materials. This requirement can be satisfied by the use of new kind of elastomers filled by nanofillers, such as carbon nanotubes. Nanocomposites based on commercial ethylene vinyl-acetate (EVA) copolymer and multiwalled carbon nanotubes (MWCNT) were prepared by casting from solution. The non-covalent surface modification of MWCNT was carried out by special, newly synthesized compatibilizer cholesteryl 1-pyrenecarboxylate (PyChol). In order to mimic Braille character, special home-built silicone punch and die moulds were used. The Brailleelement based on EVA/MWCNT-PyChol composite displays reversible, multiple changes of dimension in thedirection of the irradiation during/upon illumination by red and blue light-emitted diode (LED). Transmission electron microscopy (TEM) showed a good dispersion of the MWCNT-PyChol within the matrix. The Braille element behaviour under illumination was analysed by atomic force microscopy (AFM) and by nanoindentor. Nanoindentor, even if the purpose of its original use is different, can be effectively applied for the determination of the actuation stroke, the sample dimensional changes in the directionof irradiation.