Shapeshifting materials have captured the imagination of researchers for their myriad potential applications, yet their practical development remains challenging. These materials operate by mechanical actuation: their structural responses to external stimuli generate mechanical work. Here, we review progress on the use of flexible metal–organic frameworks (MOFs) in composite actuators that shapeshift in a controlled fashion. We highlight the dynamic behaviour of flexible MOFs, which are unique among materials, even other porous ones, and introduce the concept of propagation, which involves the efficient transmission of flexible MOF deformations to the macroscale. Furthermore, we explain how researchers can observe, measure, and induce such effects in MOF composites. Next, we review pioneering first-generation MOF-composite actuators that shapeshift in response to changes in humidity, temperature, pressure, or to other stimuli. Finally, we allude to recent developments, identify remaining R & D hurdles, and suggest future directions in this field.

中文翻译：

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在宏观尺度上传播 MOF 的灵活性：基于 MOF 的机械执行器的案例

变形材料因其无数的潜在应用而吸引了研究人员的想象力，但它们的实际开发仍然具有挑战性。这些材料通过机械驱动运行：它们对外部刺激的结构反应产生机械功。在这里，我们回顾了在以受控方式变形的复合致动器中使用柔性金属有机框架 (MOF) 的进展。我们强调了柔性 MOF 的动态行为，这在材料（甚至其他多孔材料）中是独一无二的，并引入了传播的概念，它涉及柔性 MOF 变形到宏观尺度的有效传输。此外，我们还解释了研究人员如何在 MOF 复合材料中观察、测量和诱导此类效应。下一个，我们回顾了开创性的第一代 MOF 复合材料执行器，这些执行器会根据湿度、温度、压力或其他刺激的变化而发生变形。最后，我们提到了最近的发展，确定了剩余的研发障碍，并提出了该领域未来的发展方向。