Abstract The intelligent poly N,N-dimethylacrylamide hydrogel material system with high mechanical strength and the 3D printable property was prepared via in situ free radical polymerization under vacuum successfully. With the increase in nanofibrillated cellulose (NFC) content, stress and strain of hydrogels increased gradually. As the effective reinforcement, NFC enhanced the crosslinking density, which realized the controllable regulation of rheology behaviors including viscosity, storage modulus, and loss modulus of hydrogels. Combined with the swelling rate and the existence of the gel–sol transition point, a hydrogel with 10 mg/mL NFC was treated as the 3D printing ink of hydrogel actuators. Variation of printing parameters significantly affected self-driven deformations. The hydrogel actuators with 90°/0° and 45°/135° configurations owned bending and spiral deformations, respectively. Actuators with a larger length–width ratio owned a lower pitch value. The precise anisotropic swelling property of the printed bilayer structure was the self-driven deformation mechanism of hydrogel actuators, which provided material candidates for the preparation of soft robots and actuators.

中文翻译：

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3D打印智能聚N,N-二甲基丙烯酰胺水凝胶驱动器的设计与制备

摘要 通过真空下原位自由基聚合成功制备了具有高机械强度和3D打印性能的智能聚N,N-二甲基丙烯酰胺水凝胶材料体系。随着纳米原纤化纤维素（NFC）含量的增加，水凝胶的应力和应变逐渐增加。作为有效的增强剂，NFC提高了交联密度，实现了对水凝胶粘度、储能模量和损耗模量等流变行为的可控调节。结合溶胀率和凝胶-溶胶转变点的存在，将具有 10 mg/mL NFC 的水凝胶作为水凝胶致动器的 3D 打印墨水。印刷参数的变化显着影响自驱动变形。具有 90°/0° 和 45°/135° 配置的水凝胶致动器分别具有弯曲和螺旋变形。具有较大长宽比的执行器具有较低的螺距值。打印的双层结构精确的各向异性溶胀特性是水凝胶致动器的自驱动变形机制，为软机器人和致动器的制备提供了候选材料。