Confinement Induced Preferential Orientation of Crystals and Enhancement of Properties in Ferroelectric Polymer Nanowires

The physical properties of polymers strongly depend on the molecular or supermolecular order and orientation. Here we demonstrate the preferential orientation of lamellar crystals and the enhancement of ferro/piezoelectric properties in individual poly­(vinylidene fluoride-<i>co</i>-trifluoroethylene) (P­(VDF-TrFE)) nanowires fabricated from anodic alumina oxide (AAO) templates. The crystallographic <i>a</i> axis of P­(VDF-TrFE) was found to be aligned along the long axis of nanowires due to geometrical confinement and grapho-expitaxial crystals growth. The alignment of lamellar crystals in P­(VDF-TrFE) nanowires and enhancement of crystallization translated into improved ferro/piezoelectric properties such as lower coercive field and higher piezoelectric coefficient, testified by piezoresponse force microscopy images and piezoresponse hysteresis loops