Preparation and characterization of UV-cured composite films containing ZnO nanostructures: Effect of filler geometric features on piezoelectric response

ZnO nanofillers, with different morphologies, were synthesized by a facile aqueous sol-gel approach and embedded, at low concentration (i.e. 4 wt.%), into a UV-curable acrylic system. SEM observations showed a homogeneous distribution of the fillers within the cured network. The different morphologies of ZnO nanostructures were found to significantly affect the thermo-oxidative stability and the glass transition temperature of the obtained UV-cured films. Microcantilevers, made of the prepared films with sputtered aluminum contact, were fabricated by using standard microfabrication technology and their piezoelectric response was investigated both at the resonance frequency and at lower frequency values. Despite the low ZnO content, all the UV-cured nanocomposite films showed interesting piezoelectric properties: in particular, the devices containing flower-like nano-structures exhibited the highest root mean square voltage both at 150 Hz and at the resonance frequency (about 0.176 ± 0.001 and 0.914 ± 0.001 mV, respectively). In addition, these devices also showed maximum peak-peak voltage values at both the selected frequencies.