He Yi, Guo Jiayu, Yang Xiazhen, Guo Bing, Shen Hangyan
College of Materials and Chemistry, China Jiliang University Hangzhou 310018 PR China
The Institute of Industrial Catalysis, Zhejiang University of Technology Hangzhou 310032 PR China.
RSC Adv. 2021 Nov 23;11(60):37744-37751. doi: 10.1039/d1ra08174h.
Ambient humidity plays an important role in the fields of industrial and agricultural production, food and drug storage, climate monitoring, and maintenance of precision instruments. To sense and control humidity, humidity-responsive actuators that mimick humidity responsive behavior existing in nature, have attracted intense attention. The most common and important class of humidity actuators is active bilayer structures. However, such bilayer structures generally show weak interfacial adhesion, tending to delaminate during frequent bending and restoration cycles. In this work, to address this problem, a novel monolayer humidity-driven actuator with no adhesive issue is developed by integrating the swellable metal-organic frameworks (MIL-88A) into thermoplastic polyurethane films. The proposed actuators display excellent humidity response that under the conditions of relative humidity simulated with saturated salt solution, the MIL-88A/polyurethane composite films show good self-folding response and stability for recycling use. In addition, a deep insight into the self-folding of the composite films is also provided and a new response mechanism is proposed. In this case, the results show that both the preparation method and response properties of the humidity actuators are improved. Therefore, it suggests a new promising way to develop and design flexible humidity actuators.
环境湿度在工农业生产、食品与药品储存、气候监测以及精密仪器维护等领域发挥着重要作用。为了感知和控制湿度，模仿自然界中湿度响应行为的湿度响应致动器引起了广泛关注。最常见且重要的一类湿度致动器是活性双层结构。然而，这种双层结构通常表现出较弱的界面附着力，在频繁的弯曲和恢复循环过程中容易分层。在这项工作中，为了解决这个问题，通过将可膨胀金属有机框架（MIL-88A）集成到热塑性聚氨酯薄膜中，开发了一种不存在附着力问题的新型单层湿度驱动致动器。所提出的致动器表现出优异的湿度响应，即在饱和盐溶液模拟的相对湿度条件下，MIL-88A/聚氨酯复合薄膜显示出良好的自折叠响应和循环使用稳定性。此外，还对复合薄膜的自折叠进行了深入研究，并提出了一种新的响应机制。在这种情况下，结果表明湿度致动器的制备方法和响应性能均得到了改善。因此，这为开发和设计柔性湿度致动器提供了一种新的有前景的方法。
