Wang Kaojin, Zhu X X
Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada.
ACS Biomater Sci Eng. 2018 Aug 13;4(8):3099-3106. doi: 10.1021/acsbiomaterials.8b00671. Epub 2018 Jul 6.
Two-way reversible shape memory polymers (2W-SMPs), especially those that are light-responsive, are highly desirable for many applications, especially in the biomedical field, because of the convenience of indirect heating. We have designed and prepared a series of light-actuated 2W-SMP composites by incorporating very small amounts of polydopamine (PDA) nanospheres into semicrystalline polymer networks based on biodegradable poly(ε-caprolactone) copolymers. PDA nanospheres can be well dispersed in chloroform and well mixed with the polymer network. PDA nanospheres manifest good photothermal effect because of their strong absorption of light. The variation in temperature of the polymer composites can be correlated with irradiation time, light intensity, and the content of PDA nanospheres. Equations are developed to fit the temperature changes of the materials as a function of irradiation power and of the PDA particles content for a better understanding of the kinetics of the light-to-heat conversion. These polymer composites show excellent two-way reversible shape memory effects (2W-SMEs) under stress-free condition when the light is switched on and off showing a reversible angle change of 45°. The speed of angle change is larger for polymer composites irradiated with a stronger light or with a higher content of PDA nanospheres. This is the first report on 2W-SMPs using incorporated PDA nanospheres as photothermal fillers. A moving robot is designed based on photoresponsive 2W-SMP composites, which can walk on a track with triangular saw-teeth. This composite is capable of lifting and lowering a weight, acting as artificial muscles, and its actuated stress is much higher than the maximum stress yielded by most mammalian skeletal muscles. The use of biodegradable polyesters and thermal fillers made of a natural compound dopamine makes such composites potentially useful as biomaterials.
双向可逆形状记忆聚合物（2W-SMPs），尤其是那些对光有响应的聚合物，由于间接加热的便利性，在许多应用中，特别是在生物医学领域，具有很高的需求。我们通过将极少量的聚多巴胺（PDA）纳米球掺入基于可生物降解的聚（ε-己内酯）共聚物的半结晶聚合物网络中，设计并制备了一系列光驱动的2W-SMP复合材料。PDA纳米球可以很好地分散在氯仿中，并与聚合物网络充分混合。由于PDA纳米球对光的强烈吸收，它们表现出良好的光热效应。聚合物复合材料的温度变化与辐照时间、光强度和PDA纳米球的含量相关。建立了方程来拟合材料温度随辐照功率和PDA颗粒含量的变化，以便更好地理解光热转换动力学。当光打开和关闭时，这些聚合物复合材料在无应力条件下表现出优异的双向可逆形状记忆效应（2W-SMEs），显示出45°的可逆角度变化。对于用较强光或较高含量的PDA纳米球辐照的聚合物复合材料，角度变化速度更大。这是关于使用掺入PDA纳米球作为光热填料的2W-SMPs的首次报道。基于光响应性2W-SMP复合材料设计了一个移动机器人，它可以在带有三角形锯齿的轨道上行走。这种复合材料能够提起和放下重物，起到人造肌肉的作用，并且其驱动应力远高于大多数哺乳动物骨骼肌产生的最大应力。使用可生物降解的聚酯和由天然化合物多巴胺制成的热填料使得这种复合材料有可能作为生物材料使用。
