4D Printing of Seed Capsule‐Inspired Hygro‐Responsive Structures via Liquid Crystal Templating‐Assisted Vat Photopolymerization

Abstract

The creatures in nature exhibit dynamic responses to environmental stimuli through their hierarchical architectures. Benefiting from gradient porous structures, Delosperma nakurense opens its protective valves of the seed capsules when hydrated with liquid water, increasing the likelihood that seeds are dispersed under conditions favorable to germination. Here, a versatile 4D printing technology, namely liquid crystal templating‐assisted vat photopolymerization (LCT‐VPP), which can fabricate bioinspired porous structures with hygro‐responsive capabilities by utilizing photopolymerization induced phase separation (PIPS) and liquid crystals (LCs) electro‐alignment is reported. PIPS within the LCs/nanofiller composites leads to the formation of submicrometer gradient porous structures after extracting nonreactive LCs. The electric field enables the programmable alignment of LCs, which in turn elongates the porous structures and aligns nanofillers. In addition, the programmable arranged nanofillers by the templated LCs enhance the degree of deformation and thus the resulting composites exhibit high shape control accuracy, fast dynamic response, and high reliability. This study opens a perspective for designing bioinspired smart materials with the special spatial distribution of porous structures. The results reported here can give rise to various potential applications in soft robots, smart anticounterfeiting devices, flexible sensors, and ultrafiltration membrane.

Structure‐induced Intelligence of Liquid Crystal Elastomers

“…[25] A printed bionic hygroscopic pentagram actuator could perform dry bending and wet swelling under humidity stimuli. [30] Soft LCEbased grippers have the ability to manipulate objects owing to their large bending curvature and strong grasping force (Figure 4F). [6a,16c,25] A thin string or rod attached to the center of mass suspends the soft robotic gripper and heavy objects are grabbed and then transferred to receiver containers under stimuli.…”

Interrelations between Printing Patterns and Residual Stress in Fused Deposition Modelling for the 4D Printing of Acrylonitrile Butadiene Styrene and Wood–Plastic Composites

“…The fourth dimension refers to the capability of a 3D-printed object to transform over time when subjected to external stimuli. Through the design of material systems and control of the manufacturing process, 4D-printed products are programmed with the self-morphing functionality that can be activated by various environmental changes such as heat [2][3][4][5][6][7][8][9], moisture [10][11][12][13][14][15], pH [16][17][18][19][20], electricity [21][22][23][24], and magnetic field [25][26][27][28][29][30]. It offers the possibilities to fabricate objects that can self-transform from simple into complex geometries, reducing the need for support structures, minimizing the production time, and saving manufacturing costs.…”