Department of Chemistry, University of California, Riverside, Riverside, CA, 92521, USA.
Materials Science and Engineering Program, University of California, Riverside, Riverside, CA, 92521, USA.
Small. 2022 Feb;18(6):e2105356. doi: 10.1002/smll.202105356. Epub 2021 Dec 2.
Organic phase change materials are used in actuators like wax motors. The solid→liquid phase transition that drives expansion is commonly induced by resistive heating that requires an electrical connection. The use of light to generate a phase change provides a non-contact way to power wax motors. Here, it is demonstrated that small molecules can act as absorbers to enable a photoinduced solid→liquid melting transition in eicosane, a low molecular weight phase change material. Three different small molecule absorbers are utilized: (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), azobenzene (AZOB), and guaiazulene (GAZ). The GAZ/eicosane mixture is characterized in detail because its absorption extends out to 750 nm, opening up the possibility of using near-infrared diodes as the photon source. The GAZ/eicosane composite is incorporated into a commercial wax motor assembly and 532 nm laser light is used to lift up to 400 g. The temporal response, work and force output, and efficiency are measured, and no loss of lifting capability or degradation is observed after ten cycles of irradiation. The incorporation of small aromatic molecules with low-energy absorption features into phase change materials can provide a general way to make light powered wax motors.
有机相变材料被用于蜡质电动机等执行器中。推动膨胀的固-液相变通常是通过电阻加热引起的，这需要电连接。利用光来产生相变提供了一种非接触式的方法来为蜡质电动机供电。在这里，证明了小分子可以作为吸收剂，在低分子量相变材料二十烷中实现光诱导的固-液熔融转变。使用了三种不同的小分子吸收剂：(2,2,6,6-四甲基哌啶-1-基)氧自由基（TEMPO）、偶氮苯（AZOB）和愈创木薁（GAZ）。详细表征了 GAZ/二十烷混合物，因为其吸收延伸到 750nm，为使用近红外二极管作为光子源打开了可能性。将 GAZ/二十烷复合材料装入商用蜡质电动机组件中，并用 532nm 激光提升高达 400g。测量了其时间响应、功和力输出以及效率，并且在照射十次循环后没有观察到提升能力的损失或降解。将具有低能量吸收特征的小分子掺入相变材料中，可以为制造光驱动的蜡质电动机提供一种通用方法。
