Research data for: Graded metallopolymer structures with shape-memory abilities via DLP-based 3D-prining

In this study, the digital light processing (DLP) based three-dimensional (3D) printing of graded metallopolymer structures with shape-memory ability is presented. Herein, ligand-containing monomers based on terpyridine and triphenylmethyl(trt)-histidine are complexed with zinc(II) and nickel(II) salts, respectively. Subsequently, photopolymerization with 2-phenoxy ethyl acrylate as comonomer is conducted. During 3D-printing, resin vat exchanges are performed after a certain amount of printing time. The newly added resin mixture is based on a different metal-ligand combination and can be printed under the same conditions as the previous mixture, thereby resulting in graded structures.

The obtained materials are characterized according to their thermo-mechanical properties via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Temperature dependent Raman spectroscopy is utilized to investigate materials with a special focus on the interface between the different segments. Here, a narrow dynamic region at the intersection thinner than one printing layer (about 20 µm) was detected.

During the shape-memory investigation the graded structures enable the recovery of the permanent shape in two distinct steps showing excellent shape-memory behavior. Thermo-mechanical analysis (TMA) measurements reveal fixity rates after mechanical deformation close to 100% and overall recovery rates as high as 99%.

本研究报道了具备形状记忆性能的梯度金属聚合物结构的数字光处理（Digital Light Processing, DLP）三维打印方法。本文中，分别以基于三联吡啶和三苯甲基（trt）-组氨酸的含配体单体与锌(II)、镍(II)盐进行配位复合。随后以丙烯酸苯氧乙酯作为共聚单体开展光聚合反应。在三维打印过程中，每经过一段固定时长的打印作业后便更换树脂槽内的树脂体系。新添加的树脂混合物采用不同的金属-配体配位组合，且可在与此前树脂一致的工艺条件下完成打印，最终得到梯度化的三维结构。

通过差示扫描量热法（Differential Scanning Calorimetry, DSC）与热重分析（Thermogravimetric Analysis, TGA）对所得材料的热机械性能进行表征。采用温度依赖性拉曼光谱对材料展开研究，重点聚焦不同结构段之间的界面区域。研究发现，在界面处存在厚度小于单打印层（约20 μm）的窄动态过渡区域。

在形状记忆性能测试中，梯度结构可通过两个独立步骤实现永久形状回复，展现出优异的形状记忆行为。热机械分析（Thermo-mechanical Analysis, TMA）测试结果显示，机械变形后的形状固定率接近100%，整体形状回复率高达99%。