Shape memory effect and light-induced deformation in Schiff base molecular crystals/PVDF ferroelectric polymer composites

Polyvinylidene difluoride (PVDF)-based polymers have been extensively investigated as a type of electroactive polymer because of their wide applications in flexible sensors, actuators, and transducers. In this work, we demonstrate a new functionality of the PVDF-based polymer-shape memory effect (SME). We show that this effect mainly originates from the ferroelectric-paraelectric phase transition and that shape recovery can be realized at a high speed (<100 ms), superior to most of the existing shape memory polymers. We synthesize modified Schiff base light-sensitive materials and compound them with the polymer to achieve composites exhibiting light-activated SME in the visible light range by exploiting the photothermal effect of the Schiff base compounds. Furthermore, the composites possess light-induced deformation because of the isomerizationinduced volume change of the Schiff base molecules under light illumination. To demonstrate the application potential of the multifunctional composites, flexible actuators and robots were designed by combining the thermal-, light-, and electric field-activated SME or deformation. This study not only proposes new multifunctional composites with good application potential, but also presents a new mechanism to design shape memory polymers and expands the functionality of PVDF-based ferroelectric polymers.

Automated summary

In this study, a new functionality of PVDF-based polymer, shape memory effect, is demonstrated, which mainly originates from the ferroelectric-paraelectric phase transition. By compounding modified Schiff base light-sensitive materials with the polymer, composites exhibiting light-activated shape memory effect in the visible light range are achieved, and light-induced deformation is also obtained. Flexible actuators and robots are designed by combining different activation methods, showcasing the potential applications of these multifunctional composites. This study proposes new composites with good application potential and expands the functionality of PVDF-based ferroelectric polymers.