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 isomerization-induced 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.

中文翻译：

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希夫碱分子晶体/PVDF铁电聚合物复合材料的形状记忆效应和光致变形


聚偏二氟乙烯（PVDF）基聚合物作为一种电活性聚合物已被广泛研究，因为它们在柔性传感器、执行器和传感器中广泛应用。在这项工作中，我们展示了基于 PVDF 的聚合物形状记忆效应 (SME) 的新功能。我们证明这种效应主要源于铁电-顺电相变，并且可以高速（<100 ms）实现形状恢复，优于大多数现有的形状记忆聚合物。我们合成了改性席夫碱光敏材料，并将其与聚合物复合，利用席夫碱化合物的光热效应，获得在可见光范围内表现出光激活SME的复合材料。此外，由于席夫碱分子在光照射下异构化引起的体积变化，复合材料具有光致变形。为了展示多功能复合材料的应用潜力，通过结合热、光和电场激活的 SME 或变形来设计柔性执行器和机器人。这项研究不仅提出了具有良好应用潜力的新型多功能复合材料，而且提出了设计形状记忆聚合物的新机制并扩展了PVDF基铁电聚合物的功能。