Hydrogels combined with complex 3D shapes and robust mechanical properties are extremely desired soft platforms in the fields of biomaterials, recently, 4D printing has been developed to be further shaped to form required patterns. On the basis of the excellent thixotropy of Laponite and the thermal-reversible sol–gel transition of agarose and easy formation of nanofibers below 35 °C, a 4D printing hydrogel (4D Gel) was fabricated by in situ polymerizing acrylamide in the agarose matrix containing Laponite. The experimental results demonstrated that Laponite played an important role in the improvement of 4D printing, such as endowing the ink with shear-thinning behavior to extrude easily and excellent shape stability after printing. The mechanical properties of 4D Gel were unexpectedly higher than those of both agarose and polyacrylamide hydrogels. The 4D Gel showed the ability to further transform its shapes, and was used successfully to construct a whalelike hydrogel, which opened mouth and cocked tail by treating with an external force and then cooling, as well as the octopus like hydrogel with waved tentacles to seem to “come alive”. This work opened a new avenue for creating more complex architectures than 3D with excellent properties, which is important in the macromolecule fields for the wide applications.

中文翻译：

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由琼脂糖纳米纤维和聚丙烯酰胺组成的坚固水凝胶的 4D 打印

水凝胶与复杂的 3D 形状和强大的机械性能相结合，是生物材料领域非常需要的软平台，最近，4D 打印已被开发用于进一步成型以形成所需的图案。基于 Laponite 优异的触变性和琼脂糖的热可逆溶胶-凝胶转变以及在 35 ℃以下容易形成纳米纤维，在琼脂糖基质中原位聚合丙烯酰胺制备了 4D 打印水凝胶（4D Gel）。锂皂石。实验结果表明，Laponite 在改进 4D 打印方面发挥了重要作用，例如赋予墨水剪切稀化行为以易于挤出和打印后出色的形状稳定性。4D Gel 的机械性能出乎意料地高于琼脂糖和聚丙烯酰胺水凝胶。4D凝胶显示出进一步变形的能力，并成功用于构建鲸鱼状水凝胶，通过外力处理然后冷却，它可以张开嘴翘尾，以及像章鱼一样的水凝胶，带有波浪状的触须。来“活过来”。这项工作为创建比 3D 更复杂的结构开辟了一条新途径，具有优异的性能，这在大分子领域的广泛应用中非常重要。