Research Institute of Materials Science, South China University of Technology, Guangzhou 510640, China.
Soft Matter. 2018 Mar 28;14(13):2500-2507. doi: 10.1039/c8sm00297e.
Dopamine-containing hydrogels were synthesized by copolymerization of dopamine methacrylamide (DMA), N,N-dimethylacrylamide (DMAA), and an N,N'-methylenebisacrylamide (BIS) crosslinker in a mixed solvent of water and DMSO. The association of DMA was formed by simply immersing in water to facilely reinforce the hydrogel due to the introduction of the second physical crosslinking. The tensile strength of the hydrogels was increased greatly and regulated in a wide range from 200 kPa to over 2 MPa. The association of DMA was destroyed upon immersing in DMSO. This reversible formation and dissociation of the association structure endowed the hydrogel with shape memory and actuating capabilities. Rapid shape fixing in water and complete shape recovery in DMSO was realized within several minutes. Bioinspired functional soft actuators were designed based on the reversible association and metal ion coordination of DMA, including fast responsive hydrogel tentacles, programable multiple shape change, reversible and versatile painting and writing "hydrogel paper". The facile preparation and strength regulation provide a new way to design novel soft actuators through solvent exchange, and will inspire more complex applications upon combining the association with other properties of mussel inspired dopamine derivatives.
通过将多巴胺甲基丙烯酰胺（DMA）、N,N-二甲基丙烯酰胺（DMAA）和 N,N'-亚甲基双丙烯酰胺（BIS）交联剂共聚在水和 DMSO 的混合溶剂中合成了含多巴胺的水凝胶。DMA 的缔合是通过简单地浸入水中形成的，由于引入了第二种物理交联，因此很容易增强水凝胶。水凝胶的拉伸强度大大提高，并可在 200kPa 至 2MPa 以上的宽范围内进行调节。DMA 的缔合在浸入 DMSO 时被破坏。这种缔合结构的可逆形成和解离赋予了水凝胶形状记忆和致动能力。在几分钟内即可实现水凝胶在水中的快速形状固定和 DMSO 中的完全形状恢复。受 DMA 的可逆缔合和金属离子配位的启发，设计了仿生功能软致动器，包括快速响应的水凝胶触手、可编程的多形状变化、可逆且多功能的绘画和书写“水凝胶纸”。通过溶剂交换来设计新型软致动器提供了一种简便的方法，并且在将缔合与贻贝启发的多巴胺衍生物的其他特性结合使用时，将会激发更复杂的应用。
