Moon Dowon, Lee Min-Gyu, Sun Jeong-Yun, Song Kwang Hoon, Doh Junsang
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 37673, Republic of Korea.
Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
Macromol Rapid Commun. 2022 Oct;43(19):e2200271. doi: 10.1002/marc.202200271. Epub 2022 Jun 23.
Structure changes mediated by anisotropic volume changes of stimuli-responsive hydrogels are useful for many research fields, yet relatively simple structured objects are mostly used due to limitation in fabrication methods. To fabricate complex 3 dimensional (3D) structures that undergo structure changes in response to external stimuli, jammed microgel-based inks containing precursors of stimuli-responsive hydrogels are developed for extrusion-based 3D printing. Specifically, the jammed microgel-based inks are prepared by absorbing precursors of poly(acrylic acid) or poly(N-isopropylacrylamide) in poly(acrylamide) (PAAm) microgels, and jamming them. The inks exhibit shear-thinning and self-healing properties that allow extrusion of the inks through a nozzle and rapid stabilization after printing. Stimuli-mediated volume changes are observed for the extruded structures when they are post-crosslinked by UV light to form interpenetrating networks of PAAm microgels and stimuli-responsive hydrogels. Using this method, a dumbbell-shaped object that can transform to a biconvex shape, and a gripper that can grasp and lift an object in response to stimuli are 3D-printed. The jammed microgel-based 3D printing strategy is a versatile method useful for variety of applications as diverse types of monomers absorbable in the microgels can be used to fabricate complex 3D objects transformable by external stimuli.
由刺激响应水凝胶的各向异性体积变化介导的结构变化在许多研究领域都很有用，但由于制造方法的限制，大多使用结构相对简单的物体。为了制造响应外部刺激而发生结构变化的复杂三维（3D）结构，开发了基于微凝胶的堵塞墨水，其中含有刺激响应水凝胶的前体，用于基于挤出的3D打印。具体而言，基于微凝胶的堵塞墨水是通过在聚丙烯酰胺（PAAm）微凝胶中吸收聚丙烯酸或聚N-异丙基丙烯酰胺的前体并使其堵塞而制备的。这些墨水表现出剪切变稀和自愈特性，这使得墨水能够通过喷嘴挤出并在打印后快速稳定。当通过紫外线对挤出的结构进行后交联以形成PAAm微凝胶和刺激响应水凝胶的互穿网络时，可以观察到刺激介导的体积变化。使用这种方法，3D打印出了一个可以转变为双凸形状的哑铃形物体，以及一个可以响应刺激抓取和提起物体的夹具。基于微凝胶的堵塞3D打印策略是一种通用方法，可用于各种应用，因为微凝胶中可吸收的各种类型的单体可用于制造可通过外部刺激转变的复杂3D物体。
