3D-Stereolithographically Printed Mesoscopic Microgels with Precisely Positioned Supramolecular Recognition Motifs─Soft Building Blocks for Assembly and Light Triggered Disassembly

Abstract

Mesoscopic microgels with supramolecular recognition motifs could enable their reversible assembly, representing a promising tool for reconfigurable structures for application in soft robotics. In this study, we realize such a material system that can be patterned by using sequential stereolithographic 3-D printing. The photoresist consists of 2-hydroxyethyl acrylate, ethylene glycol diacrylate, and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, together with the supramolecular recognition motifs azobenzene (Azo) and α-cyclodextrin (αCyD). Azo can be switched by light from the trans-isomer, which fits into αCyD, to the cis-conformation, which is expelled from αCyD. This optical switching leads to the triggered disassembly of the printed microgel building blocks. We print an intricate 3D geometry with the supramolecular functionalities at specific positions, allowing self-recognition of the building blocks and reversible assembly into large supra-colloidal networks.