Distributed Array of Polymeric Piezo-nanowires through Hard-Templating Method into Porous Alumina

• Main Authors: Valentina CAUDA, Davide DAPRA, Ilze AULIKA, Angelica CHIODONI, Danilo DEMARCHI, Pierluigi CIVERA, Marco PIZZI
• Format: Article
• Language: English
• Published: IFSA Publishing, S.L. 2011-10-01
• Series: Sensors & Transducers
• Subjects: Piezoelectric polymeric nanowires; Confined crystallization; Hard-templating; Anodic porous alumina membrane; Dielectrical properties
• Online Access: http://www.sensorsportal.com/HTML/DIGEST/october_2011/P_SI_154.pdf

We report on the preparation of ferroelectric polymeric nanowires through hard-templating strategy. Wet-impregnation of poly(vinylidene fluoride) (PVDF) and its copolymer poly(vinylidene fluoride-tri fluoro ethylene) [P(VDF TrFE)] was performed into commercially available porous Anodic Alumina Membrane (AAM). The polymeric nanowires show a diameter ranging from 144 to 166 nm, a length of tenth of micron and a high filling ratio of the alumina pores. X-ray diffraction pattern and infrared spectroscopy show the crystallization of both polymers into the ferroelectric β phase. In addition, Curie temperature (Tc) tests show an increase to higher Tc for the PVDF-TrFE polymeric nanowires with respect to the bulk polymeric material, thus revealing the importance of confined crystallization into mono-dimensional structures. A piezoelectric behavior was also observed by a voltage generation upon mechanical pressure, without pre-poling or mechanically orienting the polymer. These crystalline piezoelectric nanowires distributed in a vertical array would potentially address applications like mechanical pressure sensors, e.g., in robotics.