3D printed silicones have demonstrated great potential in diverse areas such as soft robots, tissue engineering, flexible sensors and energy dissipation. However, most silicone inks face inevitable curing issue once it is prepared. During the materials extrusion based printing process, the curing-related viscosity change in silicone inks hamper the ink stability and printing controllability, leading to complex relationship among ink properties and printing parameters, as well as printing structures and material properties of final products. Herein, this work presents active mixing of two component silicone ink to realize stable printing, achieving exact and continuous match of ink properties and printing parameters. Using a specially formulated ink containing separate starting components with reactive groups, catalyst and thixotropic agents, this work studies the active mixing process thoroughly for the first time from molecular level to materials performances under various conditions regarding inlet flow rates, impeller rotation speed and component ratios. Besides, cellular silicones with controlled distribution of component ratios and tailored gradient structures are printed, leading to integrated manufacturing of compression performance and shape morphing property. This work will pave way for active mixing and printing of two-component silicones, and provide guidance for other reactive multi-material 3D printing systems.

中文翻译：

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在分子水平上主动混合双组分粘弹性有机硅墨水，用于时空控制的多孔有机硅 3D/4D 打印

3D 打印有机硅在软机器人、组织工程、柔性传感器和能量耗散等领域展现出巨大潜力。然而，大多数有机硅油墨在制备后都面临着不可避免的固化问题。在基于材料挤出的打印过程中，有机硅油墨与固化相关的粘度变化阻碍了油墨的稳定性和打印可控性，导致油墨特性和打印参数以及最终产品的打印结构和材料特性之间的复杂关系。在此，这项工作提出了两种组分有机硅墨水的主动混合以实现稳定的打印，实现墨水特性和打印参数的精确和连续的匹配。这项工作使用一种特殊配方的墨水，其中含有带有反应基团、催化剂和触变剂的单独起始组分，首次从分子水平到材料性能在入口流量、叶轮转速和组分比等各种条件下彻底研究了活性混合过程。此外，还可以打印具有受控成分比例分布和定制梯度结构的多孔有机硅，从而实现压缩性能和形状变形性能的集成制造。这项工作将为双组分有机硅的主动混合和打印铺平道路，并为其他反应性多材料 3D 打印系统提供指导。