Multi-material 3D Printing of Mechanochromic Double Network Hydrogels for On-Demand Patterning

Cephalopods can change their color and patterns by activating the skin chromatophores for camouflage. However, in the man-made soft material systems, it is greatly challenging to fabricate the color-change structure in the desired patterns and shapes. Herein, we employ a multi-material microgel direct ink writing (DIW) printing method to make mechanochromic double network hydrogels in arbitrary shapes. We prepare the micro-particles by grinding the freeze-dried polyelectrolyte hydrogel and immobilize the microparticles in the precursor solution to produce the printing ink. The polyelectrolyte microgels contain mechano-phores as the cross-linkers. We adjust the rheological and printing properties of the microgel ink by tailoring the grinding time of freeze-dried hydrogels and microgel concentration. The multi -material DIW 3D printing technique is utilized to fabricate various 3D hydrogel structures which could change into a colorful pattern in response to applied force. The microgel printing strategy shows great potential in the fabrication of the mechanochromic device with arbitrary patterns and shapes.

Automated summary

Mechanochromic double network hydrogels in arbitrary shapes were created using a multi-material microgel direct ink writing (DIW) printing method. Micro-particles were prepared by grinding freeze-dried polyelectrolyte hydrogel, and then immobilized in the precursor solution to produce the printing ink. The multi-material DIW 3D printing technique was utilized to fabricate various 3D hydrogel structures that can change into a colorful pattern when force is applied.