Biasing Buckling Direction in Shape‐Programmable Hydrogel Sheets with Through‐Thickness Gradients
Biasing Buckling Direction in Shape‐Programmable Hydrogel Sheets with Through‐Thickness Gradients
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DOI：
10.1002/adfm.201905273
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发表时间：
2019-09
影响因子：
19
通讯作者：
Ying Zhou;C. M. Duque;C. Santangelo;R. Hayward
中科院分区：
文献类型：
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作者：
Ying Zhou;C. M. Duque;C. Santangelo;R. Hayward
可光交联的聚（N，N'-二乙基丙烯酰胺）共聚物允许光刻制造具有不均匀交联密度和溶胀比的水凝胶片。使用该材料系统，通过规定由膨胀的面内变化定义的“度量”，可以成功地对具有非零高斯曲率 K 的不同 3D 形状进行编程。然而，该方法不能控制每个正K特征所采用的屈曲方向，因此不能在由单个度量定义的不同等距形状之间可控地进行选择。在这里，通过调整用于交联的紫外线的吸收，在凝胶片的厚度上引入溶胀梯度，通过紫外线照射的方向局部指定每个特征的优先屈曲方向。通过控制相邻特征之间的耦合强度，这被证明是在规范波纹表面形状内对每个单元的屈曲方向进行编程的有效方法。
A photocrosslinkable poly(N, N′‐diethylacrylamide) copolymer allows for the photolithographic fabrication of hydrogel sheets with nonuniform crosslinking density and swelling ratio. Using this material system, different 3D shapes with nonzero Gaussian curvature K are successfully programmed by prescribing a “metric” defined by in‐plane variations in swelling. However, this methodology does not control the direction of buckling adopted by each positive K feature, and therefore cannot controllably select between different isometric shapes defined by a single metric. Here, by introducing gradients in swelling through the thickness of the gel sheet by tuning the absorption of the UV‐light used for crosslinking, a preferential buckling direction is locally specified for each feature by the direction of UV exposure. By also controlling the strength of coupling between neighboring features, this is shown to be an effective method to program buckling direction of each unit within a canonical corrugated surface shape.