Collaborative Innovation Center for Eco-Friendly and Fire-Safety Polymeric Materials (MoE), State Key Laboratory of Polymer Materials Engineering, National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry , Sichuan University , Chengdu 610064 , P. R. China.
ACS Appl Mater Interfaces. 2019 Dec 26;11(51):48428-48436. doi: 10.1021/acsami.9b17904. Epub 2019 Dec 12.
There have been more challenges for hydrogel actuators to meet the combined requirement of discoloration, complex deformation, and simple preparation. Structural coloration is widely used to fabricate discolored hydrogel via microrearrangement of photonic crystals in the hydrogel framework. However, precise regulation is usually required. Besides, the macro-optical properties are unstable. Herein, we develop a hierarchical and gradient hydrogel actuator with complex deformation and color-changing functions using an electrophoresis method. A simple but effective strategy is presented for fabrication of hierarchical hydrogel composed of homopolymers and copolymers via salt-induced microphase separation during the polymerization of the -isopropylacrylamide (NIPAm) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC). Meanwhile a gradient distribution of DMC is also formed during the polymerization due to migration of DMC under electric field. The hierarchical and gradient structures are characterized by confocal laser scanning microscope (CLSM), small-angle X-ray scattering measurement (SAXS), temperature-variable Fourier transform infrared (FTIR), etc. The discoloration mechanism is proposed. The as-prepared hydrogel can undergo fast and complex thermo-triggered deformation and discoloration. Bionic movements of discoloration flowering and information encryption are successfully demonstrated, promising great potential in the application of biomimetic materials.
水凝胶致动器在满足变色、复杂变形和简单制备的综合要求方面面临更多挑战。结构色广泛用于通过在水凝胶骨架中光学生色晶体的微观重新排列来制造变色水凝胶。然而，通常需要精确的调节。此外，宏观光学性质不稳定。在此，我们使用电泳法开发了一种具有复杂变形和变色功能的分级和梯度水凝胶致动器。提出了一种简单但有效的策略，通过在聚合过程中盐诱导的微相分离来制备由均聚物和共聚物组成的分级水凝胶 - 异丙基丙烯酰胺（NIPAm）和[2-（甲基丙烯酰氧基）乙基]三甲基氯化铵（DMC）。同时，由于电场下 DMC 的迁移，在聚合过程中也形成了 DMC 的梯度分布。通过共焦激光扫描显微镜（CLSM）、小角 X 射线散射测量（SAXS）、温度可变傅里叶变换红外（FTIR）等对分级和梯度结构进行了表征。提出了变色机制。所制备的水凝胶可以快速且复杂地进行热触发变形和变色。成功演示了变色开花和信息加密的仿生运动，有望在仿生材料的应用中具有巨大潜力。
